THE CIRCUMPOLAR ACTIVE LAYER MONITORING (CALM) PROGRAM: RESEARCH DESIGNS AND INITIAL RESULTS 1

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1 THE CIRCUMPOLAR ACTIVE LAYER MONITORING (CALM) PROGRAM: RESEARCH DESIGNS AND INITIAL RESULTS 1 J. Brown International Permafrost Association P. O. Box 7, Woods Hole, MA K. M. Hinkel Department of Geography, University of Cincinnati Cincinnati, OH F. E. Nelson Department of Geography and Center for Climatic Research University of Delaware, Newark, DE Abstract: The Circumpolar Active Layer Monitoring (CALM) program, designed to observe the response of the active layer and near-surface permafrost to climate change, currently incorporates more than 100 sites involving 15 investigating countries in both hemispheres. In general, the active layer responds consistently to forcing by air temperature on an interannual basis. The relatively few long-term data sets available from northern high-latitude sites demonstrate substantial interannual and interdecadal fluctuations. Increased thaw penetration, thaw subsidence, and development of thermokarst are observed at some sites, indicating degradation of warmer permafrost. During the mid- to late-1990s, sites in Alaska and northwestern Canada experienced maximum thaw depth in 1998 and a minimum in 2000; these values are consistent with the warmest and coolest summers. The CALM network is part of the World Meteorological Organization s (WMO) Global Terrestrial Network for Permafrost (GTN-P). GTN-P observations consist of both the active layer measurements and the permafrost thermal state measured in boreholes. The CALM program requires additional multi-decadal observations. Sites in the Antarctic and elsewhere in the Southern Hemisphere are presently being added to the bipolar network. PART I. INTRODUCTION 2 Evidence continues to accumulate that climatic change is having a profound impact in the Earth s cold regions (Morison et al., 2000; Serreze et al., 2000; Anisimov et al., 2001). Long-term environmental monitoring of sea ice extent (Parkinson et al., 1999), glacier mass balance (Dyurgerov and Meier, 1997; Sturm et al., 2001), vegetation (Myneni et al., 1997), ocean temperature and circulation (Morison et al., 2000), 1All lead and contributing authors are named in alphabetical order throughout the report. A complete list of contributors is given, by country or region, in Appendix 3. 2Authors: J. Brown, K. M. Hinkel, F. E. Nelson, and N. I. Shiklomanov. 166 Polar Geography, 2000, 24, No. 3, pp Copyright 2000 by V. H. Winston & Son, Inc. All rights reserved.

2 POLAR GEOGRAPHY 167 permafrost (Osterkamp and Romanovsky, 1999), and air temperature indicate that concerns about pronounced warming in polar regions raised more than a decade ago by general circulation modeling experiments (e.g., Manabe et al., 1991) were well founded. The Intergovernmental Panel on Climate Change Third Assessment Report recently stated with very high confidence that regions underlain by permafrost have been reduced in extent, and a general warming of ground temperatures has been observed in many areas (Anisimov et al., 2001, p. 803). Changes in the ground thermal regime of cold regions have considerable potential for bringing about ecological and terrain disturbances (Moskalenko, 1998a; Forbes, 1999; Garagulya and Ershov, 2000; Osterkamp et al., 2000; Beilman et al., 2001; Jorgenson et al., 2001), and for disrupting existing foundations, roads, and other built structures. These empirical studies indicate that recent climate-induced changes in permafrost environments are widespread and accelerating. Modeling studies indicate that climate warming will continue to decrease the geographical extent of the permafrost regions (Kane et al., 1991; Anisimov and Nelson, 1996; Vyalov et al., 1998), increase the thickness of the seasonally thawed layer above permafrost (Anisimov et al., 1997), and create widespread hazards for engineered works (Smith and Burgess, 1999; Nelson et al., 2001). The Circumpolar Active Layer Monitoring (CALM) network was developed in the 1990s to address some of these concerns and scientific issues (Burgess et al., 2000). The active layer, defined as the top layer of ground subject to annual thawing and freezing in areas underlain by permafrost (Permafrost Subcommittee, 1988, p. 13), plays an important role in cold regions because most ecological, hydrological, biogeochemical, and pedogenic activity takes place within it (Hinzman et al., 1991; Kane et al., 1991). The thickness of the active layer is influenced by many factors including surface temperature, thermal properties of the surface cover and substrate, soil moisture, and the duration and thickness of snow cover (Hinkel et al., 1997; Paetzold et al., 2000). Consequently, there is widespread variation in active-layer thickness across a broad spectrum of spatial and temporal scales (e.g., Pavlov, 1998; Nelson et al., 1999; Hinkel and Nelson, in press). Geocryological investigations have been under way in both polar lowlands and mountainous regions throughout most of the past century. Other than at Russian research stations and a few other notable exceptions, most investigations of activelayer dynamics involved relatively short time periods (e.g., 3 5 years) and did not consider the consequences of long-term climatic change. Well-documented studies of active-layer response to disturbance (fire, drilling, trails, etc.) do exist, however, and these may serve as analogs of future natural changes and responses in soil climate (Walker et al., 1987; Mackay, 1995; Burn, 1998a, 1998b; Moskalenko, 1998a). In general, several decades are required following disturbance for the active layer to recover or stabilize. Prior to the 1990s, many data sets related to the thickness of the active layer were collected as part of larger geomorphological, ecological, or engineering investigations, and used different sampling designs and collection methodologies. Moreover, the typical study did not deposit data records in archives accessible for general use (see Barry, 1988). The combined effect of these circumstances made it difficult to investigate long-term changes in seasonal thaw depth or possible interregional synchronicity.

3 168 BROWN ET AL. Measurements of interannual and multi-decadal variations in the seasonal thawing and refreezing of permafrost soils on regional and hemispheric scales are required to understand and refine predictions of the response of cold soils and permafrost to climate change. The hypothesis and existing evidence that warming will increase the thickness of the active layer, resulting in thawing of ice-rich permafrost, ground instability, and surface subsidence require further investigation under a variety of contemporary environmental settings. Historical Background Several factors and events converged in the late 1980s and early 1990s to encourage development of long-term geocryological monitoring, and to make the resulting data sets freely available to interested users. These include: (1) publicity about the impacts of climate change followed two decades of unprecedented resource development in the cold regions and raised concerns about the stability of associated infrastructure; (2) permafrost scientists became increasingly aware of the benefits accruing from free exchange of data (Barry et al., 1995); (3) international agreements were signed and governments became concerned with facilitating data exchanges with interested users; and (4) the global nature of climatic change made apparent the need for widespread cooperation among permafrost scientists, who became increasingly aware of the importance of their subject in the context of recent climate change. In an initial attempt to meet the new needs and to facilitate and coordinate data acquisition procedures, the International Permafrost Association (IPA) developed the Global Geocryological Database (Barry et al., 1995). The GGD is a collection of data from pre-existing and ongoing research projects. The first CD-ROM containing GGD data was compiled and distributed by the National Snow and Ice Data Center (NSIDC) in Boulder, Colorado (IPA, 1998). An international symposium held in Yamburg, West Siberia in 1989 (Melnikov, 1990) set the stage for expanded multi-national cooperation among permafrost scientists. During the symposium, a field trip to the Parisento Research Station on the Gydan Peninsula focused attention on the need and opportunities for international cooperation in monitoring the thermal regime and thickness of the active layer. The resulting series of international scientific exchanges and site visits stimulated initiation of standardized active-layer sampling designs. By 1993, several m (1 km 2 ) grids in Alaska and western Siberia had been established. Following these early informal international activities, the CALM program was formally established in the mid-1990s as a long-term observational program designed to assess changes in the active layer and to provide ground truth for regional and global models. The CALM approach was the first attempt to collect and analyze an international geocryological data set obtained according to standardized, international methods. The initial CALM sampling design was developed in 1995 at the 6th International Tundra Experiment (ITEX) workshop, held in Ottawa, Canada (Åkerman, 1995; Brown et al., 1995). It included thaw measurements associated with the ITEX experimental design (Open Top Chambers OTC; Henry, 1997). Several types of measurement serve as minimum requirements for observing end-of-season thaw depths probing on grids ranging in size from m, through m (1 ha) to m (1 km 2 ) or along transects, and readings from permanently installed

4 POLAR GEOGRAPHY 169 thaw tubes or values interpolated from closely-spaced soil temperature sensors. The CALM protocol was revised and published in several editions of the ITEX Manual (Molau and Molgaard, 1996). Members of several working groups of the International Permafrost Association met in Ottawa during the 27th Arctic Workshop in 1997 and agreed to additional changes in the protocol. The 1997 workshop resulted in formalization of the CALM program, thus providing a basis for formal funding requests. In early 1998, a five-year CALM project was funded by the Arctic System Science (ARCSS) Program of the U.S. National Science Foundation at the University of Cincinnati to coordinate the development of sites and the collection and synthesis of data. Additional existing sites were identified and new ones initiated, particularly in Russia. The network currently incorporates approximately 100 active sites involving participants from 12 countries in the Northern Hemisphere (Fig. 1) and 3 countries involved in Antarctic research. Figure 2 illustrates the increase in the number of sites during the 1990s. By summer 2000 over 60 sites employed a grid design, with 21 grids in both Alaska and Russia. The remaining sites employ single point measurements with soil temperature cables, thaw tubes, and probing. Summary metadata for all sites, including methods used, are presented in Appendices 1 and 2. Selected site photographs are presented in Appendix 4. Data are electronically transferred to the CALM data repository at the University of Cincinnati, edited, and placed on the CALM web site (see Appendix 1). Metadata and ancillary information are available for each site, including climate, descriptions of terrain, soil type and vegetation, and site photographs. CALM data are transferred periodically to the permanent archive at the National Snow and Ice Data Center (NSIDC) in Boulder, Colorado. Initial CALM data were issued on the IPA Circumpolar Active-Layer Permafrost System (CAPS) CD (Brown, 1998) and will be updated on a second CAPS CD in The International Permafrost Association serves as the international facilitator for the CALM network, which is now part of the WMO Global Terrestrial Network for Permafrost (GTN-P). The GTN-P observations consist of the active layer measurements and the permafrost thermal state measured in boreholes (GCOS, 1997; Burgess et al., 2000). Borehole metadata are available on the Geological Survey of Canada s permafrost web site (see Appendix 1). Monitoring Methods Several traditional methods are used to determine the seasonal and long-term changes in the thickness of the active-layer: mechanical probing, temperature measurements, and visual measurements. The visual observations include reading of thaw tubes (Rickard and Brown, 1972; Mackay, 1973; Leibman, 1998) and cryostratigraphy, or stratigraphic observations of ground ice occurrences (e.g., Burn, 1997; French, 1998; Murton, 2001). Other recommended measurements include soil moisture and vertical displacement of the active layer by thaw subsidence and frost heave. Probing. The minimum observation required under the CALM protocol is a lateseason mechanical probing of the thickness of the active layer. Time of probing varies, ranging from mid-august to mid-september, when thaw depths are near their end-of-season maximum. A 1 cm diameter graduated steel rod is inserted into the soil to the depth of resistance to determine the depth of thaw. The gridded sampling design allows for analysis of intra- and inter-site spatial variability (Nelson et al.,

5 170 BROWN ET AL. Fig. 1. Map showing location of active CALM sites (dots) in the Northern Hemisphere and Antarctic, and name and location of climate stations (numbers). 1998, 1999; Gomersall and Hinkel, 2001). The size of plots or grids and length of transects vary depending on site geometry and design; grids range between 10, 100, and 1000 m on a side, with nodes distributed evenly at 1, 10, or 100 m spacing, respectively. Thaw depth is determined by making annual replicate measurements at each of the grid nodes. At some grid nodes it may not be possible to make thaw-depth measurements, owing to location in bodies of water or well-drained soils that exceed the length of the probe (usually in excess of cm). In some cases, grid nodes may coincide with such cultural features as roads or gravel pads. These missing data points are not included in calculation of summary statistics or in data analysis. Summary statistics for each sample period include average, one standard deviation, maximum and minimum, and number of points sampled. Contour maps of active-layer

6 POLAR GEOGRAPHY 171 Fig. 2. Increase in number of CALM sites by region during the 1990s. thickness are prepared by generating thaw-depth fields using a suitable interpolation algorithm (generally low-order inverse distance weighting) available in commercial software packages such as Golden Software (1999) to produce a smooth surface for visual inspection of the spatial variation in active-layer thickness. Accordance between probed measurements and the actual level of the frost table varies, because the position of the 0 C isotherm does not always coincide with the top of the frozen (ice-bearing) zone as determined by probing. For silty soils of northern Alaska and Svalbard the correspondence is generally quite good (Fig. 3; also see Mackay, 1977). Elsewhere, however, the relation is dependent on soil particle size, salinity, and temperature of the ground; errors can range from a few to tens of centimeters. If a node is probed at the same time each season, however, errors are relative. Probed depths can be corrected to the depth of the frost table if ground-temperature data are available. Many of the non-grid sampling methods are employed in forested regions, mountainous bedrock settings, or stony terrain where probing on a grid is not a practical sampling strategy. Thaw Tubes. An estimate of maximum thaw can be obtained using a liquid- or sand-filled tube (Rickard and Brown, 1972; Mackay, 1973; Nixon, 2000). Thaw tubes are employed extensively in Canada and at several Alaskan sites. The outer tube of the device is anchored in permafrost, well below the active layer, and is not subject to heave. An inner tube is filled with water or sand containing a dye. The presence of ice in the tube or the boundary of the colorless sand record the approximate position of the thawed active layer. Each summer, measurements of current thaw penetration, ground level, and maximum heave or subsidence are made relative to the outer tube, which forms a stable reference level. From these measurements it is possible to derive two values for the preceding summer: (1) the maximum thaw penetration, independent of

7 172 BROWN ET AL. Fig. 3. Plot of thaw depths determined by thermal probing versus mechanical probing in finegrained soils, Prudhoe Bay, Alaska, and Kapp Linne, Svalbard (unpublished data of F. E. Nelson and Jonas Åkerman, respectively). the ground surface and corrected to a standard height above the ground at the time of installation; (2) calculated maximum active-layer thickness, assumed to coincide in time with the maximum subsidence of the surface. In the case of the Canadian measurements, thaw penetration (marker) and surface movement (scriber) are made to 1 mm, although several mechanical factors degrade the accuracy of measurements about 2 cm (Nixon, 2000). The scriber is placed on the ground surface and moves vertically with a change in position of the ground surface position. Thaw tubes provide an inexpensive annual record of both maximum thaw penetration and active-layer thickness suitable for multi-year comparison. Thaw tubes do not, however, provide information on local variability, and individual thaw tube measurements therefore should be evaluated relative to a mean active-layer thickness field derived from more extensive sampling (e.g., probing) wherever possible. Soil and Permafrost Temperatures. Soil temperatures are commonly obtained with thermistor sensors inserted in the ground or in access tubes at variable depths in the active layer and underlying permafrost. Readings are made manually or recorded at regular time intervals by battery-operated data loggers. Most sites are now instrumented with single- or multi-channel data loggers from which the seasonal progression of freezing and thawing can be analyzed by simultaneously collecting temperature measurements from the ground surface downward into the uppermost layer of permafrost. The frequency of measurement depends on the needs of individual research projects, storage capacity of the logger, frequency of site visits, and logger battery life. The thickness of the active layer is calculated by interpolating between closely measured points at the time of maximum thaw. Measurement of temperatures

8 POLAR GEOGRAPHY 173 in the active layer and upper permafrost are made at about 75% of the CALM and associated borehole sites. Thirty-two sites are instrumented for temperature measurement of permafrost (Appendix 1). These vary in depth from less than 4 m to greater than 880 m in the case of the deep geothermal boreholes in Alaska. For purposes of the CALM program, closely spaced thermistors in the upper sections of shallow- to intermediatedepth boreholes ( m) provide data to interpolate active-layer thickness and to observe interannual to decadal changes in permafrost temperatures. Readings are made manually or at intervals by data loggers. In the case of deeper measurements where permanent cables are not installed, a single thermistor probe is lowered into the access holes and measurements made at closely spaced intervals. Soil Moisture. Soil moisture content has an important effect on soil thermal properties, soil heat flow, and vegetation. Excess moisture and ice influence the amount of soil subsidence and the resulting active-layer thickness. Soil moisture is therefore considered one of the crucial parameters for analyzing the magnitude and variability of summer thaw. Several methods are employed to measure soil moisture, including gravimetric sampling, time-domain reflectometry (TDR), and portable soil dielectric measurements. Gravimetric sampling can be used across a study area to obtain an areal average. TDR measurements are fixed in place but yield time series useful for detecting snowmelt or rain events. A scheme that allows for collection of near-surface soil moisture measurements across the study area involves use of portable electronic probes (e.g., Vitel ). These devices are employed to measure the spatial patterns of soil moisture in the uppermost soil layers, and can be useful for establishing correlations between soil moisture and maps of vegetation or thaw patterns (e.g., Miller et al., 1998; Hinkel and Nelson, in press). As with the gravimetric method, however, this results in the measurement of a highly variable quantity that is affected strongly by transient meteorological events (e.g., rainfall). In all sampling schemes, soil samples are also characterized by soil properties, including texture and organic content. Vertical Movement. Frozen ground is often supersaturated with ice (i.e., it contains excess ice). In addition to pore ice, ice lenses and ice veins contribute to the total ice content, yielding volumetric ice contents well in excess of soil porosity. Upon melting, the ice matrix disintegrates and the mineral component settles downward. This is expressed as a downward displacement of the ground surface termed thaw settlement or thaw subsidence. Probing may not detect this effect. Careful surveying is necessary to determine if thaw subsidence or frost heave has occurred. However, surveying requires a stationary benchmark not subject to vertical displacement. In the absence of bedrock, this can only be achieved by installation of a frost-defended benchmark into the underlying permafrost. Often, a steel rod is drilled into the permafrost and used for this purpose. Where surveying is not feasible, subsidence gauges are installed within the study area. These simple devices are anchored into the permafrost and mechanically record the upward and downward movement of the ground surface on a seasonal basis (see CALM web site for discussion of one such device). Further, they serve as local benchmarks and can be used to monitor vertical displacement at decadal timescales. Where thaw tubes are used the outer tube, anchored in permafrost, serves as a stable reference (Nixon, 2000). Experiments involving use of high-precision (<1 cm) differential GPS (global positioning systems) to map and

9 174 BROWN ET AL. determine the scale of variability of heave and subsidence are currently underway in northern Alaska (Nelson, Sandall, and Hinkel, unpublished data). Spatial/Temporal Distribution: The Global Hierarchical Observing Strategy (GHOST) The CALM program is a contribution to the Global Terrestrial Observing System (GTOS) and the Global Climate Observing System (GCOS) and their Global Terrestrial Networks. The networks are co-sponsored by World Meteorological Organization (WMO), the Intergovernmental Oceanographic Commission (IOC of UNESCO), the United Nations Environment Programme (UNEP), the International Council of Scientific Unions (ICSU), and the Food and Agriculture Organization (FAO). A detailed joint plan for GCOS and GTOS was developed by the Terrestrial Observational Panel for Climate (TOPC) for climate related observations (GCOS, 1997). Program goals include early detection of changes related to climate, documentation of natural climate variability and extreme events, modeling and prediction of these changes, and assessment of impacts. The Global Terrestrial Network for Permafrost (GTN-P) was approved by GCOS/GTOS to monitor, detect, and assess long-term changes in the active layer and thermal state of permafrost terrain, particularly on a regional basis. Monitoring for climate purposes under GTN-P is concerned with measuring the thickness and temperature of the overlying seasonally thawing and freezing soil (active layer) and measuring the temperature profile of perennially frozen ground. The GTN-P is coordinated by the International Permafrost Association (IPA). The affiliation of CALM within the GCOS/GTOS networks necessitates conformity with global observational protocols whenever and wherever possible. The Global Hierarchical Observing Strategy (GHOST) represents a strategic effort to obtain samples of environmental variables that can be integrated systematically over time and space to provide comprehensive estimates of the rates and magnitude of global-change impacts (WMO, 1997). Collection, documentation, and distribution of appropriate data should be insured in a sustained and timely fashion. Sites in underrepresented areas should have priority over those already well represented. Existing sites are preferred over those without instrumental or observational records. The GHOST system incorporates a nested system of five observational tiers (Table 1). The basic objective of GHOST site selection is to obtain valid regional and global coverage while taking maximum advantage of existing facilities and sites. The five-tier hierarchical system for surface observations is described briefly and illustrated below; a more complete generic description can be found in Version 2.0 of the GCOS/GTOS Plan for Terrestrial Climate-related Observations (GCOS, 1997; WMO, 1997). It is important to note that the tier structure is a classification system to aid implementation, not a rigid formula for implementation. All the tiers may not be necessary for a permafrost monitoring system. Rather, they are intended as a general guide for structuring the system. Tier 1. These are major assemblages of experimental sites subject to intensive activities over large areas, and are organized to emphasize detailed measurements and process understanding across environmental gradients or transects. They should be located with primary emphasis on spatial structure and diversity. Capturing the range of the major types of permafrost terrain is a critical priority, but location within the

10 POLAR GEOGRAPHY 175 TABLE 1 Role and Characteristics of the GHOST Tiers Tier Role Characteristics 1. Large experimental area (transects) Understand spatial structure and processes 2. Research centers (LTERs, Understand processes, large experiment stations) experimentation and data synthesis 3. Stations (small stations, watersheds) Long-term measurements over weeks to years 4. Sample sites Direct measurement, calibration, validation 5. Remote sensing (satellite Spatial/temporal interpolation observations) at scales down to days and 30 m Source: Modified from WMO, Linear dimensions of >100 km, intensive sampling, integrated data sets Basic research on ecosystems, cryosphere, with complex instrumentation Representative of range within region, frequent measurements Infrequent site visits (annual to decade; Frequent, complete coverage regions can be opportunistic. Examples of climatic/landscape gradients exist within the CALM network: the Kuparuk River basin in arctic Alaska (USA), Mackenzie River basin (Canada), Lower Kolyma River basin (Russia), and the PACE transect across the mountains of Europe to Svalbard. Tier 2. These process-oriented research sites should be located near the center of the range of environmental conditions (though not necessarily near the geographical center) of the region they represent. Actual locations depend more on existing infrastructure and logistical feasibility than on strict spatial guidelines, but there is a need to capture a broad range of climatic zones. The Tier 2 Facilities are commonly surrounded by other sites in the same ecoregion or physiographic region, and may also function quasi-independently as Tier 3 facilities. Within GTN-P are a number of potential Tier 2 candidate sites. For example, the U.S. Long Term Ecological Research (LTER) program has intensive research sites (Toolik, Bonanza Creek, and McMurdo) in different global permafrost zones. Other stations that could function effectively at the Tier 2 level include Barrow (Alaska), Zackenberg (Greenland), Abisko (Sweden), and the Murtel/Corvatsch high-altitude experimental area (Switzerland). At each of these locations intensive ecosystem and/or climatological studies are conducted in close proximity to CALM sites. Tier 3. Collectively, Tier 3 sites are intended to sample the range of environmental variation present in a permafrost-climatic zone or region. They are chosen to be representative integrated mosaics of local or landscape-scale conditions (topography, vegetation, soils, etc.). They are well-located (georeferenced and surveyed) areas in and around which intensive monitoring and critical field experiments can be performed. The well-located aspect relates to remote sensing applications, and selection criteria therefore emphasize size and position with respect to the environmental range, particularly in regions of discontinuous permafrost and mountains. Agricultural research stations and experimental watersheds located in the permafrost regions

11 176 BROWN ET AL. Fig. 4. Example of a GHOST-like hierarchical sampling strategy and time-series analysis, Kuparuk River basin, Alaska. GHOST tier structure corresponds to components of two map panels on left, as follows: Tier 1 = Kuparuk River region (entire map area; Kuparuk basin outline shown as a solid line); Tier 2 = Toolik LTER; Tier 3 = 1 km 2 CALM/ARCSS grids (squares); Tier 4 = 1 ha flux study plots (triangles); Tier 5 = remotely sensed data covering entire region (e.g., Auerbach et al., 1996; Kane et al., 1996). See Nelson et al. (1997) for detailed discussion of mapping strategy.

12 POLAR GEOGRAPHY 177 are examples. Specific examples in northern Alaska include the 1 km 2 ARCSS grids at Imnavait Creek, West Dock, Barrow, and elsewhere (Fig. 4). Tier 4. At this level, spatial representativeness is of the highest priority. Ideally, site locations should be based on statistical considerations. It is impractical to prescribe one statistical design for all regions or countries. Sites falling within Tier 4 are areas of very limited extent and data are obtained annually. Land-cover category (vegetation and soil) is the best criterion for selection and can be satellites of the Tier 3 constructs. Although strict statistical design was not applied initially, the majority of the CALM sites fall within Tier 4. For active-layer measurements to be most effective, they should be actual components of the Tier 3 facility, for example 1 ha grid cells or smaller plots on 1 km 2 CALM grids. Tier 5. To detect changes over an area (or region), satellite remote sensing may be the only practical means to bridge the gap between in situ point measurements and areal averages, eventually expanded to regional scale studies. Tier 5 of the GHOST hierarchy remains in a low state of development in the context of active-layer studies. Several investigations employing space-based platforms have achieved some success in mapping the active layer (e.g., Peddle and Franklin, 1993; Leverington and Duguay, 1996; McMichael et al., 1997), but employed very large class intervals of active-layer thickness. Kane et al. (1996) had some success using synthetic-aperture radar to estimate soil moisture in the Kuparuk basin. Ground-based radar systems (e.g., Doolittle et al., 1990; Hinkel et al., 2001) show considerable promise for direct determination of the long-term position of the active layer over limited areas; combined with an effective hierarchical sampling strategy for field verification, this technology may lead to development of a reliable and efficient mapping strategy. Examples of the GHOST approach applied to permafrost research are represented by work in the Kuparuk River basin of north-central Alaska (Nelson et al., 1997) and the PACE borehole transect in Europe (Harris et al., 2001). These studies indicate that the GHOST approach has great value in the context of permafrost research, and could be used as a model for similar integrative work elsewhere. Interested readers are referred to the original publications for detailed discussion. Harris et al. (2001) explicitly placed the components of their work within the GHOST framework. The Kuparuk study was completed before the GHOST framework was introduced. Figure 4 illustrates this work within the GHOST context. For a global observing system such as CALM to be successful, all data from a site must be freely available and open to outside users. Well-documented methods are required so that any user can easily determine what techniques were used for collection and processing. Data from the annual active-layer measurements are made available via the Internet by the end of the calendar year following their collection. Soil temperature and other observations are periodically submitted following processing. Ultimately, data are archived in the Global Geocryological Database at one of the regional WDC data centers, including the U.S. National Snow and Ice Data Center in Boulder, Colorado. Data are submitted employing procedures used in preparation of the IPA CD ROM Circumpolar Active-Layer Permafrost System (CAPS); i.e., in a digital format with appropriate metadata documentation. Investigators also agree to make historical data available.

13 178 BROWN ET AL. The CALM Network As indicated in the preceding section, the ideal distribution of sites for a global or hemispheric monitoring network should include locations representative of major ecological, climatic, and physiographic regions as prescribed under GHOST. The CALM network incorporates sites in arctic, subarctic, and mountainous regions that can be considered hemispherically representative and responsive to global change considerations. These include sites that constitute several longitudinal and latitudinal transects across northwestern North America, the Nordic region, and northeastern and northwestern Russia. Sites in Europe, China, Mongolia, and Kazakhstan provide high-elevation locations. The majority of the CALM sites are in arctic tundra regions, with the remainder in warmer forested subarctic and alpine tundra of the middle latitudes. Sites within the Antarctic continent and other Southern Hemisphere mountain and subantarctic locations are beginning to be added to CALM and the Global Terrestrial Network-Permafrost (GTN-P). The metadata descriptions for over 100 sites in the CALM network are summarized in Appendices 1 and 2. Photographs of some sites are presented in Appendix 4. Soil information for several ITEX-CALM sites was reported in Marion et al. (1997). Emphasis in this report is on temporal patterns of thaw for the period of record at CALM sites, including several multi-decade records. We restrict the discussion here to the CALM network, as these sites and new ones to be added subsequently will provide the basis for future interpretations under the internationally agreed-upon data collection and reporting protocols. Discussion of spatial patterns of thaw within grids and among regional nested grids is planned for a series of international synthesis papers, the first of which deals with the grids in northern Alaska (Hinkel and Nelson, in press). Several regional and site-specific active-layer and borehole reports were presented at the 1st European Permafrost Conference in Rome in March 2001 (Rea, 2001) and several PACE papers appeared in a special issue of Permafrost and Periglacial Processes (Harris et al., 2001). In the future, active-layer thickness will be reported from interpolated data acquired from the second borehole at each PACE site (see Mountain Permafrost Section for additional discussion of the PACE program). The CALM data presented here include end-of-summer thaw for all years of observation during the decade (Tables 2 5, 7, 8; Fig. 2). Additional pre data are contained on the CAPS CD and CALM web site. In order to establish recent baseline values or trends, the report focuses on sites with data from at least four out of five years; the vast majority of these sites have data within the last five-year period. Some earlier data and those from 2000 are still being tabulated or analyzed; the data are in the process of being added (TBA) to the CALM web site. Additional sites were added to the network in 2000, including several more PACE sites. Sites at which data have not been collected or reported during the past three years are considered inactive (see CALM web site for raw and processed data including soil temperature and moisture).

14 Regional Summer Temperature Trends POLAR GEOGRAPHY 179 The relation between end-of-season thaw depth (the response function) and air temperature (the forcing function) is described adequately by a variant of the Stefan solution (e.g., Harlan and Nixon, 1978) given by Z = E DDT, (1) where Z represents end-of-season thaw depth and correlates closely with the number of accumulated thawing degree days (DDT), generally at standard screen height, since the onset of active-layer development (Nelson and Outcalt, 1987; Hinkel and Nicholas, 1995). The relationship between these variables is modulated by sitespecific factors, which include soil thermal properties, soil moisture, and the nature of the surface cover, and are represented by the edaphic factor E (Nelson and Outcalt, 1987). The general validity of this relation has been demonstrated for northern Alaska by Zhang et al. (1997), Romanovsky and Osterkamp (1997), Nelson et al. (1998), Klene et al. (2001), Hinkel and Nelson (in press), and Shiklomanov (2001). It has also been used to map active-layer thickness at the regional scale (Nelson et al., 1997). In general, DDT is calculated by summing positive (> 0 ) daily averages of temperature over the thaw period (i.e., beginning with the initiation of thaw and ending on the last day of probing, usually in mid- to late August), or it can be estimated by summing series of consecutive mean monthly positive summer air temperatures. The summer degree-day accumulation is commonly referred to as the thawing index. In Figure 5, the thawing index at each station was calculated from air temperature records for June, July, and August. This formulation was employed to provide standardization and comparability between stations, and to promote consistency with published work treating climate records from a seasonal perspective (e.g., Stafford et al., 2000). Extensive analysis of data from northern Alaska (Shiklomanov, unpublished) demonstrated that incorporation of thawing degree days from outside these months resulted in no appreciable improvements in the ability of Eq. (1) to calculate active-layer thickness. There is general agreement between GCM predictions and observational data about temperature increases over the land areas of the Northern Hemisphere in the last several decades. However, large discrepancies exist in the seasonal and regional patterns of this change (e.g., Alt and Maxwell, 2000). Trends and patterns in the high northern latitudes identified in recent publications include a 30-year warming of mean annual temperature over most continental areas and the central Arctic Ocean, partially counterbalanced by cooling in the northern part of the North Atlantic Ocean (Serreze et al., 2000). On land, the warming trends are influenced primarily by increased temperatures in winter and spring. Summer trends are somewhat weaker, with increases generally only a few tenths of a degree, which is within the range of natural climatic variability. Areas with the strongest summer temperature increases are northwestern Canada and the central and western parts of the Russian Arctic, while cooling is indicated in southern parts of the Nordic countries, in northern Quebec, and Eastern Canadian Arctic (Serreze et al., 2000). Long-term climate records are available from weather stations in close proximity to many CALM sites. The summer air thawing degree-day totals for these stations are

15 180 BROWN ET AL. Fig. 5. Time series plots of thawing degree days (DDT) for major regions. A. Nordic countries and western Siberia. B. Central Asia. C. Northeast Russia and Alaska. D. Northwest and central Canada. E. Eastern Canada and Greenland. Data based on June, July, and August means for all stations. Data from various sources including WMO (1997) and for Canada, Environment Canada (2000). plotted, by region, for the period of available record in Figure 5. Monthly mean temperature for the three summer months (June, July, August) were used in all cases, although the thaw season may extend significantly beyond those months at some locations. Zhang et al. (1996) found that use of mean monthly temperatures to estimate degree-day totals was accurate to about 95 percent for northern Alaska, and use of this thaw index method is retained here for illustrative purposes. Nordic Countries and Western Siberia (Fig. 5A). The summer climate record from the Abisko Scientific Research Station, dating back to 1913, has been analyzed in considerable detail. Information about this station has been extended back to 1868

16 POLAR GEOGRAPHY 181 through analysis of records from several nearby stations (Holmgren and Tjus, 1996). Only minor changes in summer temperatures were observed from the 1870s to about 1910, when a rise of 1.5 C took place, ending about Since then, there has been a decline of about 0.5 C. Overall, the record from Svalbard shows a slight increase in thawing degree-day totals over the period of record. Climate stations near CALM sites in the western part of Siberia (Marre Sale and Vokuta) show relatively small magnitude, positive trends in thawing degree-day totals. The interannual variability in these records is substantial. The record for Nadym is consistent with those from the other stations in this grouping except in 2000, when a precipitous drop in degree-day totals occurred. Central Asia (Fig. 5B). Each of the stations in central Asia shows a moderate increase in degree-day totals, consistent with observations of degrading permafrost and increases in active-layer thicknesses in Mongolia (Sharkhuu, 1998), Kazakhstan (Marchenko, 1999), and China (Jin et al., 2000). Northeast Russia and Alaska (Beringia) (Fig. 5C). Stafford et al. (2000) provided a detailed analysis of temperature trends in Alaska for the period , concluding that mean annual temperatures increased throughout Alaska. Increases of temperature in winter showed the largest changes, although spring and summer temperature increases at many locations were also statistically significant. The temperature series shown in Figure 5C reflect the conclusions of Stafford et al. (2000), with moderate increases in thawing degree-day totals at all stations in Alaska and Northeast Russia. The strongest increase in summer temperature in the region is apparent in the Alaskan interior, in this case Fairbanks, again consistent with the findings of Stafford et al. (2000) for winter and spring temperatures. Northwest and Central Canada (Fig. 5D). In the Mackenzie Valley and Delta over the course of the past century, climate has changed significantly. Mackay (1975) cited several lines of evidence that indicate a 3 C increase in air temperatures from the late 1800s to the mid-1900s, followed by a 2 C decrease. From the 1970s to the mid-90s, an increase greater than 1 C has been recorded (Maxwell, 1997). Records from widely spaced stations in northern Canada west of Hudson Bay (Inuvik, Tuktoyaktuk, Fort Simpson, and Baker Lake) show moderate to strong increases in thawing degreeday totals since the mid-20th century. These increases are consistent with records from the Beringian stations. Eastern Canada, Arctic Islands, and Greenland (Fig. 5E). Many stations representing Greenland and the eastern part of the North American Arctic show no trend or very slight decreases of the thawing index in recent decades. Both Eureka and Alert show a decrease in air temperature from 1950 to the early 1980s. A general warming trend has, however, been observed since the early to mid-1980s. The eastern Canadian Arctic shows a small increase in degree-day totals in recent decades. This region was characterized as having anomolous behavior (Alt and Maxwell, 2000, p. 34). Allard et al. (1995) observed cooling of permafrost in the northeastern part of the Ungava Peninsula, but noted that active-layer thickness at their sites was variable over the period of their record, concluding that changes in winter temperatures were the primary cause of decreasing permafrost temperatures. South of the treeline at Kuujjuarapik, thawing degree-day totals have increased in recent decades.

17 182 BROWN ET AL. PART II. SITE HISTORIES AND RESULTS BY COUNTRY/REGION Presentation of site information, data, and discussion begins with Alaskan sites and moves eastward across Canada, to the Nordic countries and then across Russia. The final sections report on sites in the mountains of the middle latitudes and Antarctica. Alaska (USA) Of the 31 CALM-designated sites in Alaska, 17 have five or more years of consecutive data (Table 2). These include 10 sites with 1000 m (1 km 2 ) grids, seven 100 m (1 ha) grids associated with permafrost borehole measurements, and several transects and sites with thaw tubes. ITEX sites are located at Barrow, Atqasuk, and Toolik. An additional eight U.S. Geological Survey (USGS) sites are established near deep boreholes and record soil temperatures to one meter; these data will be reported in the future. Essentially all sites have data loggers for monitoring air and soil temperatures. All but the Fairbanks sites are north of the Arctic Circle in the Brooks Range, on the North Slope, or on the Seward Peninsula. Arctic Alaska and Seward Peninsula 3 Site Descriptions. The first CALM site in Alaska began with systematic observations by the U.S. Army Cold Regions Research and Engineering Laboratory (CRREL) at Barrow in the early 1960s (Brown and Johnson, 1965; Brown, 1969). The Barrow CRREL network originally consisted of a series of 20, m plots distributed over a 2.1 km transect extending across a large drained-lake basin, over a raised beach ridge and upland occupied by ice-wedge polygons, and terminating at a low, eroding lagoon bluff. The original network was monitored throughout the 1960s, and annual observations were resumed in This series of plots is now considered a single site under the CALM program. (Table 2, U2). The Barrow CALM 1 km 2 grid (U1) was established in 1992 and includes the main area of the CRREL plots. The active-layer observational network in northern Alaska has expanded steadily, beginning in the 1980s with the U.S. Department of Energy R4D project s Imnavait Creek site (U11) in the upper Kuparuk River basin (Brooks Range foothills) south of Prudhoe Bay (Reynolds and Tenhunen, 1996; Evans et al., 1989; Walker et al., 1989; Kane et al., 1991). Expansion continued in the early to mid-1990s with a series of 1 km 2 grids and 1 ha plots established under several Arctic System Science (ARCSS) programs of the U.S. National Science Foundation (Table 2; Weller et al., 1995; Kane and Reeburgh, 1998). Collectively, these sites have been used to map active-layer thickness over the 26,278 km 2 Kuparuk River basin (Nelson et al., 1997) using a variant of the GHOST strategy (see Fig. 4). Subsequently, less data-intensive and more theoretically based mapping results have been developed for mapping the active-layer field in the Kuparuk River basin (Hinzman et al., 1998; Shiklomanov and Nelson, 1999; Klene, 2000). Shiklomanov (2001) used a stochastic modeling approach, based 3 Authors: J. Brown, K. M. Hinkel, L. D. Hinzman, G. W. Kling, F. E. Nelson, V. E. Romanovsky, and N. I. Shiklomanov.

18 POLAR GEOGRAPHY 183 TABLE 2 Mean Active-Layer Thickness (cm) for the Alaskan CALM Sites a Site number and name Northern Alaska U1 Barrow U2 Barrow 10 m U3 Atqasuk U4 West Dock 100 m U4 West Dock b [42] [31] [21] [22] [23] [22] [22] [25] [33] [30] [26] U5 West Dock U6A Deadhorse 100 m U6B Deadhorse b [65] [52] [45] [52] [57] [55] [56] [61] [69] [70] [61] U7 Betty Pingo U8 Franklin Bluff 100 m U8 Franklin Bluff b [69] [60] [61] [67] [68] [67] [59] [65] [79] [70] [60] U9 Happy Valley 100 m n.d. U10 Happy Valley U11 Imnavait Creek U12 Toolik U13 Toolik LTER U14 Galbraith Lake 100 m n.d. U15 Chandalar Shelf 100 m 35 n.d U16 Old Man 100 m U26 Ivotuk A 100 m U26 Ivotuk B 100 m U26 Ivotuk 55 Seward Peninsula U27 Council U28 Kougarok Interior Alaska U17 Wickersham transect U18 Bonanza Creek LTER n.d U19 Pearl Creek thaw tubes aall sites are 1000 m grids unless otherwise indicated; n.d. = no data; TBA = to be added. See Appendix 3 for responsible site individual(s). b Interpolated active layer values from closely spaced soil temperature measurements.

19 184 BROWN ET AL. in part on eq. (1), to produce a 13 year ( ) spatial time series of the Kuparuk active-layer field. Project-oriented (Tier 4) thaw measurements were initiated when the National Science Foundation (NSF) Arctic LTER project began at Toolik Lake in 1986, and a formal grid ( m, 98 points) was established in 1990 in a small catchment of moist, acidic tussock tundra just south of Toolik Lake (U13). The grid is probed for depth of thaw on July 2 and August 11 of each year (Kling, 1995). By the late 1990s, eleven 1 km 2 grids had been established across Arctic Alaska, extending onto the Seward Peninsula. Now designated as ARCSS/CALM grids, (Hinkel and Nelson, in press), the majority of the sites are distributed along two transects from the Arctic Ocean to the foothills of the Brooks Range. Three grids are situated on the northern edge of the Arctic Coastal Plain (Barrow [U1], and West Dock [U5] and Betty Pingo [U7] in the Prudhoe Bay region). These sites have low relief, contain thaw lakes and drained or partially drained thaw-lake basins, and moist to wet acidic tundra. Atqasuk (U3), a fourth site on the Coastal Plain, is located inland on sandy deposits about 100 km south of Barrow. Three other grids are adjacent to the Trans-Alaska Pipeline and Dalton Highway in the Arctic Foothills at Happy Valley (U10), Imnavait Creek (U11), and Toolik (U12) nearly due south of Prudhoe Bay. At these foothills sites the surface deposits are largely glacial till of various ages, some with a discontinuous cover of loess. The Ivotuk foothills site (U26), established in 1998 about 300 km south of Barrow in the Arctic Foothills, has several 1 ha plots collocated in the 1 km 2 grid. Vegetation is primarily tussock and shrub tundra with weathered bedrock close to the surface. The site is located near the Lisburne deep borehole, which has a permafrost thickness of 290 m and ground temperature of 6.3 C (Lachenbruch et al., 1998). Two Seward Peninsula grids were established in 1999 at Kougarok (U28 at Quartz Creek) and Council (U27). Kougarok is representative of large areas of the interior Seward Peninsula with well-developed tussock tundra, small patches of shrubs, and continuous permafrost. The Council site is representative of the subarctic transitional region where boreal forest gives way to tundra, and has tussock tundra with white spruce and alder in one area. It is underlain by warm continuous permafrost, but thermokarst is evident on much of the grid. Four small watersheds are being studied in areas of thin (~15 m) to discontinuous permafrost and sites of well-documented tundra fires. Temperatures are recorded at meteorological stations and soil temperature profiles and borehole sites. Starting in 1996, an additional array of seven 1 ha grids was co-located at arctic and subarctic borehole sites that were established in the 1980s to measure permafrost temperatures (Table 2; Romanovsky and Osterkamp, 1997). Several transects and sites with point measurements were established starting in the 1970s in the Fairbanks area at Wickersham (U17) and Pearl Creek (U19) and later at the Bonanza Creek LTER site (U18). These Alaskan active-layer sites, positioned from the Bering Sea eastward across Alaska and joining the Canadian sites in the Mackenzie River, form a longitudinal transect representative of increasing continentality from west to east. Digital elevation models (DEMs) are available for the 1 km 2 ARCSS/CALM grids. Repeat surveys utilizing differential GPS will provide information on subsidence or heave if the underlying ice-rich permafrost has been thawing or refreezing.

20 POLAR GEOGRAPHY 185 Fig. 6. Statistical representation of active-layer observations from six CALM sites in Arctic Alaska from 1995 to 2000 (Hinkel and Nelson, in press). In this and subsequent figures, the dots represent the areally averaged annual thaw depth, with bars extending one standard deviation in either direction; the upper and lower ticks indicate the minimum and maximum thaw depths, respectively, recorded on the grid for each year. Analysis and Results. Temporal trends and annual statistics for the Coastal Plain and Foothills 1 km 2 grids are illustrated in Figure 6 (see Table 2 for average values). Sites on the Coastal Plain have substantially greater dispersion around the average value. The average standard deviation for Coastal Plain sites, exclusive of Barrow, is nearly twice that of the Foothills sites. This is the result of large contrasts in thaw depth in drained lake basins compared to the polygonized uplands at Coastal Plain sites, which leads to a strongly bimodal distribution. By contrast, thaw depths tend to be more spatially uniform in the tussock-dominated tundra on the Foothills. These grids show shallow thaw in the early 1990s, followed by a deepening throughout the 1990s with maximum thaw depths in 1998 and shallower thaw since. Mean active-layer thickness at sites in Arctic Alaska ranged from just over 20 cm at Barrow and West Dock in the early 1990s to 72 cm at Franklin Bluffs in 1998 (Table 2). In 1998, one of the warmest years on record in northwestern North America (Environment Canada 1999), all sites experienced their maximum average depth of thaw. By contrast, the summer of 2000 was cool, and minimum average thaw depths

21 186 BROWN ET AL. Fig. 7. Active-layer statistics for the 1960s and 1990s for two sites at Barrow, Alaska. were recorded at all sites. This demonstrates a regionally consistent response to air temperature forcing. For Barrow, the time series of thaw dating back to the 1960s is shown in Figure 7. A plot of DDT against average thaw depth (Fig. 8) yields two distinct linear relations, reflecting fundamentally different responses during the decades of the 1960s and the 1990s. The same surface energy input in the 1990s yielded only about 70 percent of the thaw depth achieved in the 1960s. This situation indicates that development of the active layer at Barrow resembles a Markov process: following a series of years in which it remains relatively constant, the depth of thaw is reset abruptly to a much higher or lower value. Such changes appear to be triggered by summers with unusually large or small degree-day accumulations (Nelson et al., 1998). Values of average maximum thaw depth in subsequent years cluster around this new level until resetting occurs following the next extreme summer. These changes occur at irregular intervals involving decadal time scales, and can involve doubling or halving active-layer thickness in sequential years. At Barrow, this may be due to the build-up of ice at the base of the active layer or in the uppermost permafrost. Alternatively, a shift might be the result of extreme changes in soil moisture or ground ice content over two or more years. The unusually shallow thaw reported at many sites in 1991 and 1992 was also observed at Toolik in 1991; this year experienced the lowest DDT for the 10-year period of record ( ). Thaw maxima occurred in the summers of , in accordance with other northern Alaskan sites, although there is no apparent trend in the Toolik decadal data (Table 2; G. Kling, pers. comm.). The July and August probings at Toolik provide evidence related to thaw as a function of the age of the glaciated land surface. In July, the young surface has a significantly deeper thaw than the old surface but the absolute value is small (2 cm difference). At the time of maximum thaw in August, this pattern is reversed and the young surface has a shallower thaw by about 3.7 cm than the old surface. Active-layer thicknesses, based on interpolated soil temperature recordings, are available from GTN-P-designated borehole sites along the route of the Trans-Alaska Pipeline (Romanovsky and Osterkamp, 1997). Soil temperature values are based on measurements from the surface to a depth of one meter, starting in The time

22 POLAR GEOGRAPHY 187 Fig. 8. Relationship between active-layer thickness and thawing degree days for the 1960 and 1990s for two sites at Barrow, Alaska. series of active-layer thicknesses interpolated temperature measurements for the three coastal sites are plotted in Figure 9. Active-layer thickness generally increased from 1987 to summer 1989, when air temperatures were much warmer than most years. The 1989 maximum was followed by a decrease to the widespread 1992 minimum. There was a return to pre-1992 values for the remainder of the decade, with maximum (1998) and minimum (2000) values registered by both the soil temperature and probing methods. Interannual variation at the West Dock site was twice as large as in the early 1990s (22 versus 42 cm). The West Dock site experienced the same minimum thaw in 1992 (22 cm) as did Barrow, but did not start to recover ( reset ) until For comparative purposes, probed measurements from the 100 m grids have been made since 1996 (Table 2). Average probed values for the grids are slightly greater than those obtained by interpolation of the temperature profiles, which represent single-point measurements. Similar comparison of interpolated active-layer thickness based on soil temperatures with probed values from the Barrow grids for the years showed good agreement and had a high correlation with accumulated thaw degree days (Hinkel et al., 2001, Hinkel and Nelson, in press). Future analyses will continue to explore the spatial variability between the positions of the 0 C isotherm interpolated from temperature profiles and the frost table determined by probing, which is more dependent on the presence of ice. Interior Alaska, Fairbanks 4 Three sites are located in the vicinity of Fairbanks in interior Alaska. Thaw measurements began three decades ago at Pearl Creek (U19 in 1968) and Wickersham 4Author: L. A. Viereck.

23 188 BROWN ET AL. Fig. 9. Interpolated active-layer thickness ( ) from soil temperature loggers for three sites in the Prudhoe Bay region, Alaska. Dome (U17 in 1971) as part of studies conducted by Les Viereck, Institute of Northern Forestry (Viereck and Lev, 1983). The Bonanza Creek Long Term Ecological Research (LTER, U18) site was established in The three sites have vegetation dominated by black spruce forest and are located within 50 km of Fairbanks International Airport, which has a mean air temperature of 3.5 C. The mean annual air temperature at Wickersham was estimated to be 5.2 C and snowfall about 25 percent more than recorded at the airport (Viereck, 1982). The Wickersham CALM site is part of a major fire-effects study and consists of a 20 m transect probed at 2 m intervals (Viereck and Dryness, 1979). The Pearl Creek site consists of three thaw tubes, as described by Rickard and Brown (1972), and an adjacent 10 m line for probing. Thaw at the Bonanza Creek site is measured at 20 points in a m vegetation plot. Average active-layer thicknesses from these three time series and the DDT for Fairbanks are presented in Figure 10. Using the Fairbanks thaw indices, there is no significant correlation of summer air temperature with thaw depth over the period of record. Shallow thaw years (1976, 1996, 1999) resulted from low snow covers the previous winter (Table 2). There is less agreement in the pattern of deeper thaw years (e.g., 1995). However, Pearl Creek and Wickersham do show similar annual fluctuations, especially during the period from 1990 to The annual thaw at the colder Wickersham site is approximately 10 cm shallower than at the Pearl Creek site. There appears to be no overall increasing trend in thaw depth over the 29-year study period. Thaw depths at Pearl Creek in the first decade of the study showed no trend, ranging between 51 and 59 cm. During the period , there was a regular increase, with the maximum thaw of 69 cm occurring in As a result of a low snowfall through January of 1996 and a moderately cold winter, soil temperatures

24 POLAR GEOGRAPHY 189 Fig. 10. Time series of active-layer thickness for three subarctic sites near Fairbanks, Alaska. were the lowest recorded during the period of study at the site. The following summer, in spite of a thawing index only slightly below normal (1907 C days), the thaw level was only 55 cm, bringing the thaw level back to that of the 1970s. From 1997 through 2000, values fluctuated between and 55 to 65 cm. During the 10 years of record at the Bonanza LTER site, extreme values were measured in two consecutive years (39 cm in 1999 to 59 cm in 2000), but otherwise followed a pattern similar to that found at Pearl Creek and Wickersham (Table 2). The range of values at the LTER site has been greater than at either of the other two sites. Recent studies in the Fairbanks area report current thermokarst development under natural conditions (Osterkamp et al., 2000; Jorgenson et al., 2001). Some evidence exists at the Pearl Creek thaw tube site that subsidence or thawing of ice-rich permafrost is occurring. These observations warrant further investigation, employing methods of improved vertical control. Canada Of the 21 active CALM-designated sites in Canada, there are 15 with long-term records (Table 3). Thirteen sites are located along two transects situated in the Mackenzie River Valley and operated by Federal government agencies: Geological Survey of Canada [GSC] (Nixon, 2000) and Agriculture and Agri-Food Canada (Tarnocai et al., 1995). Several additional long-term, active-layer monitoring programs include CALM sites on the Arctic Islands (four sites), two sites in the Hudson Bay region (Allard et al., 1995; Smith et al., 2001), and two recently designated sites in the Canadian Rockies (see Mountain Section). In addition to these CALM-designated sites, a

25 190 BROWN ET AL. TABLE 3 Mean Active-layer Thickness (cm) for the Canadian CALM Sites a Site number and name Mackenzie Valley C3 North Head n.d C3 North Head 100 m C4 Taglu n.d. n.d. n.d. C4 Taglu 100 m C5 Lousy Point n.d C5 Lousy Point 100 m C6 Parsons Lake [ ] C7 Reindeer Depot C7 Reindeer Depot 100 m 110 C8 Rengleng River C8 Rengleng River 100 m C9 Mountain River C10 Pump Station [ ] C11 Norman Wells C11 Norman Wells 100 m C12 Great Bear River [ ] C13 Ochre River n.d C14 Willowlake River C15 Fort Simpson n.d. n.d. n.d. n.d. C15 Fort Simpson 100 m Rocky Mountains C21 Marmot Basin #2 [ ] talik C22 Kluane Lake 100 m Arctic Islands C1 Alexandra Fjord 100 m n.d. n.d C16 Lake Hazen [ ] TBA C18 Tanquary Fjord 100 m 56 n.d. 58 n.d. C19 Eureka 1000m n.d. 49 C2 Devon Island* 60m Hudson Bay Region C17 Sheldrake River [ ] n.d TBA TBA TBA C20 Baker Lake [ ] athaw tube measurements unless otherwise indicated as grid (m) or [ ] interpolated active layer value from closely spaced soil temperature measurements; n.d. = no data or thaw exceeded tube length; TBA = to be added; * = inactive site; see Appendix 3 for responsible site individual(s).

26 POLAR GEOGRAPHY 191 number of studies and publications from northwestern Canada provide records of long-term active-layer changes related to fire [ ] (Burn, 1998a, 1998b) and [ ] (Mackay, 1995) and ecological controls (Smith et al., 1998). Mackenzie Valley. 5 The GSC network was initiated in 1990 along a 1200 km transect in the Mackenzie Valley to monitor processes linking climate, active layer, and permafrost (Nixon, 2000). The northwest-trending transect originates in the boreal forest just north of the sporadic permafrost zone, crosses the discontinuous permafrost zone, and terminates in continuous permafrost and tundra at the Beaufort Sea coast. The network is comprised of 60 sites. Site instrumentation consists of about 60 thaw tubes, and about half of the sites have air temperature screens and ground surface temperature sensors with data loggers. Thaw tubes record maximum annual thaw penetration (measured relative to a fixed reference point) and maximum heave and subsidence at the ground surface, thus making it possible to calculate maximum active layer thickness. Upon initiation of the CALM program, 10 sites along the transect were designated as CALM sites (Table 3 and Appendices 1 and 2). The second network in the Mackenzie Valley, initiated in 1986, encompasses 23 sites over 1400 km; the southern section includes the 869 km Norman Wells pipeline route from the upper to mid Mackenzie Valley (Tarnocai et al., 1995; Burgess and Tarnocai, 1997). Three of these sites (C6, C10 and C12) were designated as CALM sites. Soil temperatures are measured to a depth of 150 cm and the thickness of the active layer is estimated by interpolation of the soil temperature profiles or physically probed (Table 3 and Appendices 1 and 2). The southern sites show a significant increase in thaw penetration starting in the late 1990s. Although active-layer thickness did not increase significantly, subsidence increased notably in thin active layers underlain by ice-rich permafrost. The active-layer thickness and thaw penetration for 12 of the 13 CALM sites are plotted by region in Figure 11. Active-layer thickness from the entire GSC monitoring transect (through 1999) ranges from 32 to 189 cm (Nixon, 2000) and appears to vary from site to site as a result of a complex interplay between site-specific and regional factors. Regression analysis reveals no significant relation between active-layer thickness and latitude. As was observed in Alaska, thaw depths in 1998 were the greatest since 1991 across the northern Mackenzie Delta region when very strong El Niño conditions resulted in the warmest year on record in Canada; there was a measured increase of as much as 21 cm in thaw penetration (Wolfe et al., 2000). Several features of thaw penetration and consequent active-layer development can be discerned by comparing thaw penetration to active layer development, site to site and environment to environment over the period of record (Fig. 11). Thaw penetration has increased at most CALM sites from year to year at least until 1998, exceptions being Parsons (C6) with a peak by 1994, and Mountain River (C9) showing only slight variation. The general increase is interrupted by a noticeable decrease in 1996 north from Norman Wells and the anomalous warm year in 1998 causing an apparent decline in 1999 at all but boreal sites. The 1996 decrease corresponds to the lowest summer mean air temperature for this area in five years, with August and September means being about 2 degrees lower than normal (Canadian Meteorological Centre, 1996). The increase in 1998 results, undoubtedly, from the warmest year on record. In 5Authors: M. M. Burgess, L. Kutny, F. M. Nixon, and C. Tarnocai.

27 192 BROWN ET AL. Fig. 11. Active-layer thickness and penetration for the 12 CALM thaw tubes and temperature probe sites along the Mackenzie River valley transect. the Mackenzie Valley, summer air temperatures were higher than normal by 2 to 4 degrees from south to north (Environment Canada, 2000) and the onset of thawing temperatures was early and the thaw season longer in the Mackenzie Delta (Smith et al., 2001). At certain sites such as on the Richards Island tundra and at Willowlake River in the boreal region as well as many others on the transect, the year 2000 also shows less thaw penetration, indicating a cooler and/or shorter season. These perturbations illustrate the sensitivity of the method to inter-annual variations of this

28 POLAR GEOGRAPHY 193 magnitude, as well as the strong influence of site specific factors resulting in a complex response. A second feature of interest when comparing regions is the similarity in patterns and extent of seasonal thaw between tundra, subarctic, and boreal regions. Delta sites are a special case due to age and temperature of permafrost, proximity to surface water, and snow-trapping vegetation, as at Fort Simpson (C15), where ephemeral permafrost is suspected close to the boundary with sporadic discontinuous permafrost. Great Bear River (C12) was burned in 1995 and shows response to this change in ground cover in subsequent years. Air thawing degree days at tundra sites in the Mackenzie Delta are less than in the boreal forest, while active-layer thicknesses in both regions are similar. Larger values of air DDT are required in the boreal forest than in tundra to achieve similar active-layer thickness; perhaps this is a reflection of the insulating effect of thick moss and surface vegetation, and greater snow pack at the valley sites compared to the northern tundra. At some sites, notably in the delta and boreal environments, increases and decreases of active-layer thickness track thaw penetration consistently. This suggests that the factors that contribute to thaw settlement as thaw penetration progresses at these sites are uniform with increasing depth. At delta sites, surface movements are small, indicating that, though these silty sediments should be frost susceptible, there is little ice segregation in the active layer during freezing and little excess ice encountered by advancing thaw penetration. Other sites indicate a variable response of active-layer development to increasing thaw penetration. For instance, at Lousy Point (C5) active-layer thickness decreased in 1992 despite a slight increase in thaw penetration over the previous season. At Norman Wells (C11) a steady increase in thaw penetration, allowing for the anomalies in 1996 and 1998, is accompanied by a slight but steady decrease in active-layer thickness until Using thaw penetration (rather than active-layer thickness) for comparison of inter-annual thaw between sites and environmental zones simplifies the interpretation by eliminating such local complexities as ground-ice melting and soil compaction. During at least the initial stage of increasing thaw penetration, active-layer thickness measurements alone may underrepresent or even fail to detect the increase. Conversely, certain geotechnical problems such as pile performance or permafrost hydrology i.e., active layer storage and transport capacity would benefit more from an estimate of active-layer thickness and its changes than from thaw penetration depths alone. Arctic Islands. 6 Four sites are located on Ellesmere Island (Table 3, Appendix 1). As part of the soil climate program, C. Tarnocai installed a soil temperature logger at Lake Hazen in the Ellesmere Island National Park in 1995 (Tarnocai et al., in press). Active-layer thickness, based on interpolation methods, has fluctuated between 43 and 52 cm during the period of record. A site associated with the International Tundra Experiment (ITEX) program was established at Alexandra Fjord (Freedman et al., 1994) in 1995 and, although the record is not complete, the values are in a similar range as those at Lake Hazen. Several grids were established at Eureka and Tanquary Fjord in 1997, but the present record is incomplete. The IBP Tundra Biome site on Devon Island was re-activated for CALM, but was discontinued after several years 6Authors: G.H. R. Henry, A. Lewkowicz, and C. Tarnocai.

29 194 BROWN ET AL. (Bliss, 1977). This site has the future potential to obtain data for comparison with the 1970s thaw record. Hudson Bay Region 7. CALM sites have been designated on both the east and west side of Hudson Bay at Sheldrake, Quebec and Baker Lake, Nunavut, respectively. The Baker Lake site, located about 400 km west of Hudson Bay in the District of Keewatin, was established in conjunction with ITEX. Ground temperatures to a depth of 3 m have been measured since the fall of 1997 at Baker Lake, in a collaborative project involving the Geological Survey of Canada, University of Toronto, Environment Canada, and Orin Durey. The site is located on a gentle south-facing slope. The glacial drift overburden varies from several meters in thickness to granitic bedrock outcrops. Soils consist of coarse gravels and sands with a peat layer up to 15 cm thick. Permafrost is continuous in this region and is about 200 m thick. Ground temperatures are measured at 50 cm intervals and data are recorded manually on a monthly or semimonthly basis. Maximum summer thaw depths, interpolated from the ground temperature profile, have increased from 1.2 m in 1997 to 1.89 m in 2000 (Table 3), with the largest increase occurring in An increasing trend in mean annual ground temperatures has been observed throughout the monitoring period, because of larger increases in temperature occurring in winter compared to summer. At a depth of 3 meters for example, the mean annual ground temperature has increased by 1.7 C between 1998 and Strong El Niño conditions in 1998 resulted in the warmest year on record in Canada since 1948 (Environment Canada, 1999). In the Baker Lake area, however, only late summer and fall (August November) air temperatures were anomalously warm in Air temperatures remained warm during the fall of 1998 and freezing of the active layer was delayed. Warmer ground temperatures in the late summer and early fall, and the extension of the thaw season by about two weeks, resulted in greater thaw penetration in 1998 compared to the previous year (Smith et al., 2001). An interesting feature of the ground temperature record is the overall increase in winter ground temperature during the monitoring period. Winter air temperatures in 1999 and 2000 (January to April) were higher than those recorded in 1998 and these warmer air temperatures are associated with higher winter ground temperatures during 1999 and 2000 compared to Monthly air temperatures for January to April 1999 for example, were up to 7 C higher than those in 1998 and ground temperatures at a depth of 0.5 m were 2 5 C higher. A series of ground temperature measurement sites was established in northern Quebec adjacent to and in conjunction with airport construction (Allard et al., 1995). Based on the available ground temperature records beginning in 1986 and the environmental setting adjacent to Hudson Bay, Sheldrake was selected as a CALM site. Located in the discontinuous permafrost zone, the site occupies a peaty permafrost mound or palsa about 4 m high with a thin discontinuous peat cover of about 30 cm and punctuated by mudboils. The frozen, uplifted marine clays are ice rich. Numerous thermokarst features are found in the region. Ground temperatures were measured to the depth of 2 m. A second, parallel cable was installed in 1998 to a depth of 3 m; both cables are connected to a single data logger with a multiplexer. Interpolated 7Authors: M. Allard, M. M. Burgess, S. L. Smith, and J. Svoboda.

30 POLAR GEOGRAPHY 195 active-layer thickness from early winter measurements (December and January) is reported in Table 3. In all years, the surface layers had started to freeze back at the time of maximum zero isotherm penetration. Thaw between 1990 and 1997 ranged between 1.08 m in the cold summer of 1992 to 1.57 m in 1997, with 905 and 1,344 thaw degree days, respectively. The thermal profiles in the underlying permafrost clearly showed that the climate cooled somewhat from 1990 to 1992, and that 1992, the year after the Pinatubo eruption, was the coolest. Permafrost temperatures have been warming from 1996 to the present (Allard, pers. comm.). Nordic Region The CALM sites are located in four areas surrounding the North Atlantic northeast Greenland at Zackenberg (G1, G2), west Greenland on Disko Island (G3), the west coast of Svalbard at Kapp Linne (S1) and Calypostranda (P1), and a series of alpine and subarctic sites in the vicinity of Abisko, northern Sweden (S2). The Kapp Linne and Abisko data are among the longest continuous records in the CALM network, and provide concurrent baseline results for all three major permafrost environments: arctic, subarctic, and alpine. For the 1990s records, the Greenland thaw varied between 44 and 74 cm, the peaty and alpine sites near Abisko between 51 and 76 cm and 91 and 119 cm, respectively, and the peaty and mineral sites from Kapp Linne between 39 and 59 cm and 96 and 121 cm (Table 4). Data from Calypostranda at the Polish station on Svalbard complement the Nordic network. New grids were established by O. Humlum at Longyearbyen in 2000 (N3) and a m grid at Ny Ålesund in There are three PACE boreholes in the region (Table 4). Kapp Linne, Svalbard and Abisko, Sweden. 8 In 1972, 20 sites were established at Kapp Linne, Svalbard, for monitoring the active layer (Åkerman, 1980, 1995). During the first two years, random sampling at 10 points within m plots were used for measurement of the active layer. Starting in 1974, the grid size was increased to m, with 25 random points sampled annually until In 1994, probing of all grid points was started using methods established by CALM protocol. The two sampling methods were compared for five plots in 1994 and showed no significant difference. Therefore, the results for 1972 to present are treated as one continuous record. Ground temperature profiles were obtained at 12 sites from 1972 to Ground temperatures also were monitored in a shallow borehole to a depth of 7 m. The major part of the sampled site occupies a wide strandflat characterized by a set of raised beach ridges up to 60 m asl. The thin gravel cover overlies ice-rich silty and clayey marine deposits. The plots are considered representative of the major vegetation and landform types of the study area and, in general, of the west coast of Svalbard, a region of continuous permafrost. In 1978, 11 sites were established in the valley and mountains surrounding Abisko, Sweden. Eight grids are located in an area of peat plateaus and palsa bogs along a 120 km east-west transect at elevations between 380 to 480 m. Three grids are located in the mountains above the treeline between 850 and 950 m on patterned ground and pingo-like mounds, colluvium, and solifluction and lacustrine deposits 8Author: H. J. Åkerman.

31 196 BROWN ET AL. TABLE 4 Mean Active-Layer Thickness (cm/m) for the Nordic and European CALM Sites a Site number and name DENMARK Greenland G1 ZEROCALM G2 ZEROCALM G3 Disko Norway N2 Juvvasshoe (PACE) Svalbard N1 Janssonhaugen (PACE) N3 UNISCALM 100 m 96 POLAND Svalbard P1 Calypsostranda transect n.d n.d. 135 n.d. 136 SWEDEN S2 Abisko peat S2 Abisko alpine Svalbard S1 Kapp Linne peat S1 Kapp Linne mineral SWITZERLAND CH1 Murtel-Corvatsch (PACE) CH2 Schiltorn (PACE) apace observations based on interpolated values of closely spaced temperature measurements rounded to 0.1m for > 3 m. Non-PACE sites based on probing of approximate 100 m grids or transects. Additional PACE site to be added in the future (see Table 6). See Appendix 3 for responsible site individual(s). (Åkerman and Malmstrom, 1986). The area lies within the discontinuous permafrost zone. At Kapp Linne, eight of the original plots are considered for the period of record, one of which consists of peat. Figure 12 shows annual maximum thaw for the two soil types, and the summer DDT (thaw index) for the 29-year record. Seasonal thaw for the mineral soils showed an apparent decline from early 1970s values above 100 cm to minimum values in the 80 cm range in the 1980s. During the 1990s, thaw was again in excess of 100 cm in mineral soils, with a 1993 maximum of 120 cm. The

32 POLAR GEOGRAPHY 197 Fig. 12. Time series of active-layer thickness for peaty and mineral sites from Kapp Linne, Svalbard. peaty site at Kapp Linne showed a similar pattern with a more obvious increase in the 1990s, consistent with visual field observations that areas of palsa-like mounds have largely disappeared (H. J. Åkerman, pers. comm.). At Abisko, several trends are discernible in the composite record for the mountain sites (Fig. 13). Following maximum thaw of 110 cm in 1979, there were several periods of 3 5 consecutive summers with relatively shallow thaw. During the last half of the 1990s, a marked increase occurred with peak values of 120 cm in 1998, not unlike the maximum values noted in 1998 in northwestern North America. The peaty valley sites show a similar pattern in annual thaw, but with lower amplitude. There was visual evidence of degradation of the small palsa mounds and the surface of the larger peat plateaus. On the peat plateaus, some wet areas of sedges are replacing the dry shrub heath, indicating ground subsidence as a result of thawing of the underlying ice-rich permafrost (H. J. Åkerman, pers. comm.). The strong correlations between end-of-season thaw depth and DDT for both the well-drained and peaty sites at Kapp Linne and Abisko are shown in Figure 14. These high r 2 values demonstrate the strong forcing of air temperature upon thaw. Calypsostranda, Svalbard. 9 Between 1986 and 2000, monitoring of the active layer has been conducted in the Calypsostranda area of the western part of Spitsbergen (Svalbard archipelago), as part of a scientific research project of the expeditions from the Maria Curie-Sklodowska University in Lublin. Initial results were reported by Repelewska-Pekalowa (1994; Repelewska-Pekalowa and Gluza, 1988). Calypsostranda is a coastal plain adjacent to the Renard s and Scott s glaciers, 9Author: J. Repelewska-Pekalowa.

33 198 BROWN ET AL. Fig. 13. Time series of active-layer thickness for valley peats and mountain sites in the vicinity of Abisko, Sweden. situated on the western edge of Recherche Fjord (Bellsund area) in the northwestern part of Wedel Jarlsberg s Land. It forms a complex of raised marine terraces of Quaternary sands, gravels, marine silts, and boulder clay overlying Tertiary bedrock. Thickness of the active layer was measured at 300 points within different landscapes. These points were located on east-west and north-south oriented transects on the vast surface area of Calypsostranda, and other profiles with different slopes and aspects. For the most part, the method of metal rod probing was used. At several points, Danilin s frostmeters were used and soil temperature measurements were made at some locations. Different landscapes were analyzed, including those with flowing and stagnant water, with and without vegetation, on slopes, and on beach deposits. For this report, nine representative points were selected as CALM sites. Measurements characteristic of these points for the 12 summers ( , , 1998, and 2000) are incorporated into the CALM database. Summer thawing begins immediately after the snow cover recedes during the first 10 days of June. The end of the thaw season takes place in mid-august. Maximum thawing of the ground is extremely varied and controlled by local factors. The average thaw depths over the period of record ranged between 135 to 155 cm (Table 4). Thawing amounted to 196 cm in the places of flowing water. The rate of thawing was as high as 4.6 cm/day. The smallest thawing was found in places with stagnant water, and varies between 45 and 83 cm (mean thawing rate: 0.4 cm/day). Extremely low thaw occurs where the insulating effect of stagnant water was enhanced by the vegetation cover (e.g., peat on waterlogged surface). Slope and aspect are important: south-facing slopes have a greater active-layer thickness (180 cm), compared to

34 POLAR GEOGRAPHY 199 Fig. 14. Regressions of active-layer thickness and thawing degree days for the Kapp Linne and Abisko sites. north-facing slopes (140 cm). Large thaw depths occur on east-facing slopes resulting from frequent occurrence of warm winds from that direction (foehn type). Greenland. 10 Active-layer monitoring was initiated in 1996 at the Zackenberg Ecological Research Operations (ZERO) site in northeast Greenland, as part of the Geobasis Programme (Christiansen, 1999; Rasch, 1999). Thaw progression is monitored throughout the summer on two nearby plots: the m ZEROCALM1 (G1) grid and the m ZEROCALM2 (G2) grid. Soil temperatures are recorded to 130 cm and 60 cm depths, respectively, in each grid. Grid G1 is located on a slightly sloping abraded marine plain m above sea level on mainly sand with some gravels. Grid G2 occupies a snow patch site on a south-facing slope consisting of two fluvial terraces on sands and silty clays. Because of the differences between these grids, the Zackenberg plots are counted as two distinct locations in the CALM network. A meteorological station is located 25 m outside the grid G1. Initial results from the Zackenberg CALM grids were reported by Christiansen (1999). Data from grid G1 for the first four years show thawing to around 40 cm following the initial input of 45 to 125 C days; thaw rates decreased with inputs of between 296 and 354 C days in the summers of , respectively. At grid G2 there is no such relation. After 100 DDT input, thaw depth varies between 17 and 48 cm in the four years. Maximum active-layer thicknesses for grid G1 were fairly consistent in the five-year period, with averages from 60 to 66 cm. However, the persistence of the snow patch through the summer of 1999 on grid G2 resulted in a shallow active layer of 44 cm, in contrast to 60 cm in the snow-free grid G1. In the other 10Author: H. H. Christiansen.

35 200 BROWN ET AL. Fig. 15. Statistical representation of active-layer thickness for the three CALM sites in Greenland. years when the snow patch was only seasonal, the active layer was from 58 to 61 cm thick for grid G2 (Fig. 15). The interannual variation in DDT at Zackenberg is similar to that observed at Danmarkshavn, which is located about 275 km north of Zackenberg and has a record covering the period Based on DDT at Danmarkshavn, active-layer thicknesses on level ground in the Zackenberg area probably have been larger in the years around 1990 than during the monitoring period. The difference in thaw progression in the two grids at Zackenberg primarily indicates a much greater sensitivity toward winter meteorological conditions in grid G2. In 1999, increases in late-winter wind speed and amount of precipitation in the month of May enabled a very extensive snow patch to accumulate on grid G2, as was recorded by automatic digital photographing of the site (Christiansen, 2001). Thus, even small-scale variations, especially in latewinter meteorological conditions, exert more control on active-layer thaw progression than does the summer air temperature in topographically complex terrain where snow patches accumulate. Locating CALM grids on both flat surfaces without summer snow patches and in topographical lee sites around seasonal and sometimes perennial snow patches permits a better differentiation between effects of changes in both summer and winter meteorological conditions on active-layer thawing. The best correlation between active-layer thickness and summer air temperature (DDT) is obtained from CALM grids on level ground without summer snow patches. The climatologically most sensitive areas in periglacial landscapes with respect to response in active-layer thickness to meteorological variations are at topographical lee sites, where more snow can accumulate, than in flat areas. The influence of winter meteorological conditions (which dominate for nine months of the year) is larger on the CALM sites located around natural snowpatches (as at site G2) and/or at sites with tall vegetation. A third grid (G3) was established in West Greenland in 1997 on Disko Island, at the site of geomorphological and geocryological research (Humlum, 1998). This site is located on the top of a large moraine ridge on nearly flat ground. The grid is

36 POLAR GEOGRAPHY m and is probed annually in late summer. Soil temperatures to 70 cm in the center of the grid have been recorded since the grid was established. Initial results from this grid were reported by Christiansen (1999). Annual active-layer thickness varied between 57 and 75 cm. This large difference is mainly due to the difference in timing of the measurements. The initial shallow value from 1997 was measured on 15 July, and are not comparable with the others from August. The DDT values, based on data from a nearby meteorological station in Qeqertarsuaq, vary between 642 and 837 C days. The deepest active layer was recorded when DDT was at a minimum in Probing of the grid most often takes place during mid- to late August. According to Humlum et al. (1999), the maximum thaw depth at Qeqertarsuaq occurs in midto late September. Therefore, the reported active-layer thicknesses presumably do not represent the maximum thaw for the Disko Island CALM grid. Russia Routine geocryological observations on permafrost conditions have been conducted at over 25 permafrost stations throughout Russia. By the early 1990s, there were about 25 stations, each containing 8 10 plots and boreholes to depths of m for measuring ground temperatures (Pavlov, 1996). Some of these stations such as Polar Tundra Zonal Station, Nadym, Marre Sale, Tiksi, and Cherskiy are still operating and have established CALM grids in their vicinities. In addition, soil temperatures to 3.2 m depth have been measured at climatological stations throughout Russia for the past years (Gilichinsky et al., 1998). All 20 active CALM sites in Russia have grids of either m or m, and several sites have supplemental transects that pre-date the establishment of CALM (Table 5, Appendix 1). Thirteen sites have data from at least four of the last five years. The Russian CALM network extends from the European tundra of the Perchora and Vorkuta regions to West Siberia and the Lena Delta, eastward to the lower Kolyma River, and to Chukotka on the shores of the Bering and Chukchi seas. The majority of the CALM sites lie within the zone of continuous permafrost. Although there are many research and monitoring sites throughout the permafrost regions of Russia (Pavlov, 1996), we focus on those sites supported directly by CALM. Initial results from selected grids across the Russian Arctic are presented in Figure 16. Specific sites are discussed in the following regional sections. West Siberia 11 The first CALM site was established in 1992 at the VSEGINGEO Parisento field station on the Gydan Peninsula. The average thaw depth from 1992 to 1995 on this CALM grid increased from 82 to 94 cm (Table 5). Unfortunately, by 1996, the excessive cost of helicopter charter resulted in discontinuing the site. A replacement grid was established in 1995 at the former VSEGINGEO Marre Sale permafrost station and is now monitored by personnel of the Earth Cryosphere Institute (ECI) of the Russian Academy of Sciences (Vasiliev et al., 1998; Pavlov and Moskalenko, 2001). At two other well-established West Siberian sites, CALM grids were initiated by 11Authors: M. O. Leibman, E. S. Melnikov, N. G. Moskalenko, A. V. Pavlov, and A. A. Vasiliev.

37 202 BROWN ET AL. TABLE 5 Mean Active-Layer Thickness (cm) for the Russian CALM Sites a Site number and name European Tundra R2 Ayach-Yakha R23 Talnik R24 Bolvansky West Siberia R1 Nadym Transect n.d. n.d R1 Nadym R3 Marre Sale Transect R3 Marre Sale 1000 m R4 Parisento 1000 m* n.d. 94 R5 Vaskiny Dachi Transect R5 Vaskiny Dachi Taymyr Peninsula R6 Labaz Lake* R7 Levinson Lessing Lake* Lena River R8 Tiksi Lower Kolyma River R13 Cape Chukochii 37# n.d R13A Cape Chukochii 31 R14 Chukochya River 43 36# R15A,B Konkovaya River 39 44# n.d. R16 Segodnya Pingo 38 n.d. n.d. 30 n.d. R17 Akhmelo Channel 44 56# 43 n.d. 45 R18 Mt. Rodinka R19 Lake Glukhoe R20 Malchilovskaya Channnel 54 n.d R21 Lake Akhmelo 85 n.d R22 Alazeya River n.d. R25 Jakutkoe Lake Chukotka Peninsula R9 Cape Rogozhny R11 Mt. Dionisiya R27 Lavrentia 58 a# = 100-m grids in 1997; n.d = no data; * = inactive site; see Appendix 3 for responsible site individual(s).

38 POLAR GEOGRAPHY 203 personnel of the ECI: Vaskiny Dachi in 1993 and the Nadym site in Both have previously measured thaw data from transects. These three sites form a latitudinal transect of some 500 km. Figure 17 illustrates average thaw depth for the periods of record. For the longer record at Marre Sale and Nadym, a five-year smoothing filter was used to illustrate presence (Marre Sale) or absence (Nadym) in trends for the two time series. Marre Sale. Long-term geocryological measurements have been obtained at the Marre Sale station, located on the Yamal Peninsula on the shores of the Kara Sea (Pavlov, 1998). The active-layer sites are located on the second and third marine terraces, which are dissected by lakes, ravines, and hollows with elevations up to 40 m a.s.l. Vegetation is typical tundra, consisting of grasses, shrubs, mosses, and lichens. Soils are mostly developed in sand and sandy loam, and peat horizons 0.1 to 0.7 m thick are common. The CALM grid is located on predominantly flat to gently sloping surfaces with some steep slopes up to 10º. Permafrost is continuous, and mean annual temperatures range between 4º and 6ºC (Moskalenko, 1998a, 1998b). Average active-layer measurements by Pavlov (pers. comm.) since 1978 ranged between 87 and 116 cm (Fig. 17) on the transect and between 92 and 131 cm on the CALM grid (Fig. 16; Table 5). The CALM grid is located 1.5 km from the Polar Meteorological Station. Pavlov (1994, 1996, 1998) analyzed long-term climatological records for Russia and thaw records from the Parensito and Marre Sale stations. He summarized the 20th century climate as warming until the 1950s, a subsequent decrease until the mid- 1970s, followed by a rise of mean annual air temperature. There is a strong relation between summer thawing degree days and depth of thaw. The deepest thaws generally occurred during the abnormally warm summers of 1984, 1989, 1993, and The minimum thaw occurred in the cool summers of 1980 and 1992; the latter coincides with the shallow thaws in the North American Arctic and Svalbard. Interannual variation in thaw depth can be greater than percent. Pavlov estimated a thaw depth increase of 0.5 to 0.6 cm/yr over the last years. Since preparation of Pavlov s papers in the 1990s, however, a decrease in thaw depth has occurred. He compared the results of sampling from the CALM grid at Marre Sale and conventional transects and concluded that (if producing active-layer maps is not an immediate goal) statistically similar values of thaw can be obtained by reducing sampling on the m grid by approximately one-half. Vaskiny Dachi. The station, established by Marina Leibman, is situated in the central Yamal Peninsula about 90 km northeast of Marre Sale on a third fluvial-marine plain composed of Pleistocene sands, silts, and clay. The adjacent area is deeply dissected by lakes and ravines, and has flat sandy hilltops and steep to flat slopes. Elevations range between 25 and 56 m a.s.l. Vegetation consists of sedges, mosses, and shrubs up to 90 cm high. Occurrence of landslides, lateral erosion, ice- and sandwedge polygons, saline marine permafrost, and massive ground ice of more than 15 m thickness have been reported (Leibman and Streletskaya, 1997; Leibman, 1998). Active-layer measurements started in 1990 along transects. In 1993, the m CALM grid was added, and since 1995, 400 additional random points were measured. Other measurements include active-layer and permafrost temperatures in boreholes. The CALM grid occupies a hilltop, mostly composed of sand, and a gentle slope with a clayey active layer. Permafrost temperatures on the grid range from 5 to 7ºC.

39 204 BROWN ET AL. Fig. 16. Statistical representation of active-layer thickness for six CALM sites across Russia. The average range of thaw depth on the CALM grid for the was cm (Table 5). For the period , the average active-layer thickness (Fig. 17) varied across a smaller relative range (16 percent) in comparison with the thaw index (47 percent). Like Marre Sale and Nadym, minimum thaw occurred during the cool summer of Nadym. The region is dominated by the Nadym River floodplains, which are composed of fine silty sands. Active-layer measurement sites are located near the Nadym- Punga pipeline, on the third lacustrine-alluvial plain at an elevation of 25 m. The CALM grid is located 30 km from the town of Nadym and the weather station. The area lies within the island permafrost and northern taiga zones. The terrain is dissected by lakes, ravines, and frost mounds. The peatlands are dominated by cloudberry, labrador tea, sphagnum moss, and Cladonia peat overlying a sandy substrate. Mean annual temperature in the upper permafrost ranges from 0.5 to 1.5ºC. The mean annual air temperature, measured 30 km to the north, is 6.3ºC. Permafrost thickness associated with extensive peatlands and floodplain deposits ranges from 5 to 20 m. Active-layer measurements by Natalya Moskalenko (pers. comm.; Moskalenko et al., 2001) since 1971 varied between 48 and 63 cm on the peaty transect (Fig. 17) and for the CALM grid between 125 and 137 cm (Table 5).

40 POLAR GEOGRAPHY 205 Fig. 17. Time series of active-layer thickness for three sites in West Siberia. Russian European North 12 Three CALM sites are located in the discontinuous permafrost region of the European tundra Ayach-Yakha and Talnik near Vorkuta and Bolvansky in the Perchora lowlands (Table 5). Talnik (Zamolodchikov and Karelin, 2001) and Bolvansky are new sites; only results from Ayach-Yakha with five years of data are discussed in detail. Ayach-Yakha. 13 This CALM grid is situated in the discontinuous permafrost zone, 13 km northeast of the town of Vorkuta. The site occupies a gentle southwestfacing slope with a creek flowing within 20 m of its lower border. Measurements include: thaw depth; snow depth; temperatures in the air, active layer, and upper permafrost; and water content in the active layer. Elevation for each grid node is available. In this area of discontinuous permafrost, permafrost-affected landscapes differ widely in the depth of active layer, ranging from 30 cm in peatlands and up to 200 cm in some sites with mineral soils. In addition, closed taliks are common. The CALM site has strongly cryoturbated mineral soils with frost boils covering 3 percent of the site area and the active-layer thickness averaging 66 cm. A shallow active layer and occurrence of frost boils are well correlated with the thin snow cover. Average maximum snow thickness on the CALM site is 30 cm compared to greater than 50 cm at permafrost-free sites. Winter and mean annual temperatures are lower on the CALM 12Authors: G.V. Malkova, G. Mazhitova, E. S. Melnikov, and D. G. Zamolodchikov. 13Author: G. Mazhitova.

41 206 BROWN ET AL. site (Mazhitova, in press). During the five years of record, minimum temperatures in the upper 20 cm layer on the CALM site ranged from 9 to 22 C, whereas in four permafrost-free sites they ranged from 2 to 6 C. Mean annual soil temperatures at a depth of 50 cm were from 3 to 4 C on the CALM site, whereas they were positive in the permafrost-free sites. The other CALM site at Talnik, located 36 km to the southwest of Ayach-Yakha, is warmer, and permafrost-affected soils have deeper thaw. Thus, taken together, the two sites represent the extremes of the temperature and thaw-depth range observable in the permafrost-affected mineral soils of the area. Air-temperature trends for Vorkuta, starting in 1944, illustrate several quartercentury long periods of cooling and warming against an overall long-term cooling trend. The warming of was characterized by temperature increments of C per year (see also Kakunov and Pavlov, 1997; Oberman and Yudina, 2000). Oberman analyzed the records of geocryological monitoring conducted from in the Usa River basin to which the CALM site belongs. Temperature data from several hundred boreholes located on different landscapes were involved. He reported (Oberman and Mazhitova, 1999) that most sites demonstrate poor correlation between mean annual temperature and thaw depth on an interannual basis. However, on a decadal and longer-term basis, most sites respond clearly to the air temperature trend. The monitoring data show that active-layer dynamics depend on the ice content in the frozen ground. The glacial-marine plain on which the CALM site is located is composed of loamy sand and loam with a relatively low ice content. For example, a borehole located on this plain had a much deeper thaw, 175 cm on average. During the period, the thaw depth increased by 24 cm, which is 13 percent of the average. The corresponding increase in a peatland site, with higher ground-ice content, was smaller by 8 cm, which is 10 percent of the average of 79 cm (Oberman and Mazhitova, in press). From the five years of CALM data, variations in grid thaw were 9 percent of the average (Fig. 16). DDT calculated from the data of Vorkuta weather station for were 835, 828, 1004, 881, and 1075 C days, while average thaw was 70, 64, 65, 64, and 69 cm, respectively. Thus, over this limited range of values, there is no close correspondence between DDT and active layer thickness at these sites. An attempt has been made to assess the magnitude of annual soil subsidence. Repeated instrumental leveling showed changes in grid node elevations between autumn 1999 and autumn The changes varied from 10 cm heave to 15 cm subsidence, resulting in the site average of 5 cm subsidence. Variations in subsidence from year to year are yet unknown. Considering that five years of record showed the 6 cm difference between the landscape minimum and maximum thaw, it is obvious that subsidence of such magnitude should be further assessed and taken into account. As indicated elsewhere in this report, without thaw subsidence data, our results relate only to the active-layer depth, and not to the dynamics of the permafrost table. Our data allow analysis of the effect of microtopography, organic-layer thickness, snow thickness, and soil water content on the thaw patterns for the Ayach-Yakha CALM site. Thaw data for Turbi-Histic (Gleyic) Cryosols (organic or O horizon 10 cm) and Gleyi-Turbic Cryosols (O <10 cm) show significant statistical differences. At the same time, small depressions do not affect thaw significantly. However, larger microhollows and microridges with sizes of 10 m or more in dimension, are clearly reflected in the thaw patterns. The smallest thaw, 35 to 45 cm, is only observable on

42 POLAR GEOGRAPHY 207 microridges, whereas thaw values of 75 to 85 cm are observed only in microhollows. The highest thaw values on the CALM grid, exceeding 85 cm, are observed in the southwestern part of the grid where soils are shallow over bedrock. Thus the effect of bedrock overshadows the effect of microhollows and microridges. Snow thickness and volumetric soil water content at the end of the thaw season did not correlate with the thaw depth (correlation coefficients 0.25 and 0.03, respectively, at p = 0.05). This can be partially explained by the location of the grid on a slope, which is influenced by the redistribution of melt waters and rainfall runoff. Central Siberia, Lena River 14 In association with the GEWEX Asian Monsoon Experiment (GAME) program in the Siberian Arctic, a 100 m CALM grid (R8) was established in 1997 near Tiksi, Republic of Sakha (Kodama, 1998). The GAME-Siberia research is conducted at the Polar Geocosmophysics Observatory 7 km southwest of Tiksi. The program is a collaborative effort of Japanese scientists from the University of Hokkaido, Mie University, and other institutions; Russian scientists from the Institute of Biological Problems of the Cryolithozone, the Permafrost Institute, and the Polar Geocosmophysics Observatory; and U.S. scientists from the University of Alaska-Fairbanks. The CALM grid supports the analysis of hydrologic processes and modeling capabilities in watersheds in the Siberian Arctic. Long-term climatic records are available from the nearby Poliarka Hydrometeorological Station, which was founded in Mean annual air temperature is 13.5ºC. Permafrost is continuous and exceeds 500 m in thickness. The CALM grid is located near the mouth of the Lena River, 5 km west of the Laptev Sea. The site occupies the floodplain and first terrace of the Suonannakh River. Soils are thin and relatively undeveloped, consisting of poorly decomposed organics overlying gravels. Vegetation is sparse in most places and consists of mosses, lichens, sedges, and dwarf shrubs. Average thaw for the four years ranged between 40 and 47 cm, with a maximum of 47 cm in summer 2000 (Table 5, Fig. 16). Lower Kolyma River 15 Beginning in 1996, a series of grids was established in the Kolyma-Indigirka Lowlands between 152 and 162º E and 68 and 72º N on the northeast Eurasian Arctic tundra and spanning a distance of approximately 200 km. Some sites were colocated with previously drilled boreholes under the direction of David Gilichinsky, Institute of Photosynthesis and Soils, and in the Cherskiy area by Sergei Zimov, Northeast Science Station (Zimov et al., 1993). Permafrost occurs throughout the area to depths of m with its average temperature of about 10ºC. The sites, except for Mt. Rodinka, are located in four different physiographic divisions adjacent to the Kolyma River. Several sites are located on the coast of the East Siberian Sea (R13, R13A) or within 5 km of the coast (R12A, R12B, and R25) (see Table 5 and Fig. 18). 14Author: Y. Kodama. 15 Authors: D. A. Gilichinsky, S. Gubin, D. Fyedorov-Davydov, V. Ostroumov, V. Sorokovikov, and S. Zimov.

43 208 BROWN ET AL. 1. Taiga: The Malchikovskaya Channel site (R20) is situated in the taiga zone on the flood basin or the present-day alluvial deposits, and includes Zimov s Pleistocene Park and the Mt. Rodinka site (R18) in the vicinity of Cherskiy. 2. Tundra: Lakes Akhmelo (R21) and Glukhoe (R19), as well as the Segodnya pingo (R16) and Akhmelo Channel (R17) sites, are situated on the sandy Khalarchinskaya tundra. The first two are on the boundary between taiga and tundra zones, with the pingo and other sites in tundra. 3. Alas: The Konkovaya site and a site on Cape Chukochii are situated in alas depressions. Alas relief consists of depressions, drained lakes and river terrace deposits (R13A, R15A). 4. Edoma ice complex: These uplands are formed from the syngenetically frozen late-pleistocene icy complex. The active layer measurements are made in the overlying epigenetically frozen cover layer of Holocene age (R12A, R13, R14, R15B, R22, R25; Table 5). The taiga sector of the Kolyma Lowland is represented by larch forests with willow and birch shrubs and a ground cover rich in mosses and lichens. Tundra vegetation belongs to the southern tundra subzone. Akhmelo, Segodnya pingo, the Alazeya and Malaya Konkovaya rivers region, and the middle course of the Chukochya River valley are rich in dwarf birch. The tundra vegetation on the Edoma surface is characterized by dwarf birch, willow, Dryas, and mosses. Polygonal swamps are developed in alas depressions and on poorly drained surfaces of large Edoma remnants. The Khalarchinskaya tundra is occupied with communities of polygonal swamps with cottongrass, sphagnum mosses, lichens, and herbs. Floodplains are characterized by the presence of Calamagrostis meadow and swamp vegetation. The soils of the Kolyma lowland are mostly Gleyic Cryosols on loamy deposits and Haplic Cryosols on sandy deposits. The Khalarchinskaya tundra is dominated by Haplic Cryosols and polygonal swamps. Oxiaquic Cryosols are developed on the drained Edoma surfaces. The highly productive parts of floodplains are characterized by Gleyic Cryosols and swamps. Thaw observations for the initial period of record for six Kolyma sites exhibit little similarity (Fig. 18). Two sites (R15A and R21) experienced minimum thaw in Average thaw depths at R14 and R20 were relatively uniform during the period of record, while R18 demonstrates an increase in average thaw depth since Chukotka Peninsula 16 The initial grids in the Chukoka region were established by Anatoly Kotov of the Anadyr Permafrost Laboratory in 1992 adjacent to the site of a tundra fire. After three years of measurements (average thaw of 59, 51, and 56 cm) the site was abandoned because of logistic constraints. Starting in 1994, two new sites (located 35 km apart) were then established between Onemen and Kanchalan bays in collaboration with the International Tundra Experiment (ITEX) program. A new site was initiated at Lavrentia (R27) along the Chukchi Sea coast in 2000 in close collaboration with the U.S. NSF ARCSS project in Alaska. (Table 5). The Cape Rogozhny (R9) and the Mt. Dionisiya (R11) grids are located in the Lower Anadyr (Nizhneanadyrskaya) Lowland, within the continuous permafrost zone. 16Authors: A. N. Kotov, V. Yu. Razzhivin, and D. G. Zamolodchikov.

44 POLAR GEOGRAPHY 209 Fig. 18. Active-layer thickness for six CALM sites along the Lower Kolyma River. Cape Rogozhny is on the northern coast of Onemen Bay and Mt. Dionisiya is about 25 km from Anadyr City. Taliks are found only beneath Onemen Bay and large lakes. Mean annual air temperature at the nearby Anadyr City weather station is 7.7 C, and mean annual precipitation is 312 mm. Mean annual ground temperature is about -5 C and the permafrost is up to 150 m thick. The hilly plain is dominated by cottongrass hummocks 20 to 40 cm in diameter covering 60 to 70 percent of the surface, while the remainder is occupied by inter-hummock depressions or troughs. Frost cracks, ice wedges, and frost boils are well developed (Kotov, 2001; Kotov et al., 1998). Fine-grained sands of Late-Pleistocene age up to 20 m thick are underlain by glacial till of Middle Pleistocene age. Holocene ice wedges are up to 2 m wide and 3 m in vertical extent. In fine-grained sands, syngenetic ice wedges are up to 2 m in width and up to 20 m high. Thermoerosion and thermocirques connected with massive ground ice occur in nearby coastal areas. At Cape Rogozhny, measurements of the active-layer thickness are obtained in inter-hummock troughs and ranged between 38 and 50 cm for the seven-year record (Table 5; Fig. 16). This relatively short period of observations allows several conclusions. Since the observational site is limited to the single landscape type (typical cottongrass-moss-hummocky tundra), the spatial variation of active-layer depth is linked to the greater thickness of the organic layer (minimum thaw) and development of frost boils (maximal thaw). The increase in the mean air temperature of approximately 3.5 C in 1996 is reflected in the increase of mean active-layer thickness within the grid of more than 6 cm (to 49 cm followed by 50 cm in 1997). Although the thawdepth increase did not activate thermokarst processes within the grid, the increased temperatures did result in activating coastal processes. In 1996 and 1997 numerous thermocirques formed as massive ground ice melted.

45 210 BROWN ET AL. The Mt. Dionisiya ITEX site (R11) is located at ~140 to 145 m a.s.l. The steep SSW slopes are dominated by forb dwarf shrub lichen vegetation. The surrounding flat and gently inclined terraces vary in texture from gravel to loam, are rich in water tracks, and vary in vegetation from shrub tundra to dwarf shrub sedge-moss tundra and dwarf shrub tussock-moss tundra. The grid is located on a slightly inclined (5-6º WSW) proluvial-deluvial mountain bottom. The site consists of a network of slowly flowing water tracks with moist sedge-cottongrass tundra and wet to mesic dwarf shrub cottongrass tussock tundra that occupy most of the site. There are some peat hillocks 1 to 4 m in diameter and 0.4 to 0.6 m high covered by dwarf shrubs and lichens. The five-year range of mean thaw for Mt. Dionisiya was 45 to 53 cm with the maximum in 1999 (Table 5, Fig.16). The thaw pattern is related to hydrology and to the thickness of the organic horizon. Thaw depth in the slowly flowing water tracks in the northwest corner of the grid approaches 60 to 85 cm. Increased thaw depth in the southwest part of the grid is probably enhanced by subsurface water movement. The minimal active-layer thickness is found under the dwarf shrub cottongrass moss tussock tundra, where it coincides with a relatively thick organic soil horizon. On bare areas (frost boils), lacking an organic horizon and plant cover, the thaw depth is twice as great. Mountain Permafrost Regions Permafrost occurs in all mountainous regions of the high latitudes and is widespread at higher elevations in mid-latitude mountain ranges, including the Qinghai- Tibet Plateau (Brown et al., 1997). Active-layer thickness is highly variable in coarsegrained or blocky clastic deposits. Ground temperatures at mid-latitude mountain sites are generally close to 0 C. The ground is unstable where ice-rich permafrost is susceptible to thawing. In Europe, the Permafrost and Climate in Europe (PACE) project, initiated in 1997, installed a series of eight boreholes (62 to 129 m deep) for the measurement and recording of permafrost temperatures (Harris et al., 2001). Table 6 presents the metadata summaries for the PACE borehole sites. Metadata from other mountainous sites of the Northern Hemisphere are included in Appendices 1 and 2. In this section of the report, we discuss both active-layer and permafrost temperature observations. In most cases the active-layer thickness is obtained from the site of the deeper borehole measurements. The interpolated active-layer thicknesses from these boreholes and shallow pits are presented in Tables 3, 4, and 7 and discussed in the following regional summaries. These mountain sites contribute to the Global Terrestrial Network-Permafrost (GTN-P). Additional mountain sites in Canada, China, Europe, Russia, South America, and Antarctica are in the process of being designated as GTN-P and associated CALM sites (Burgess et al., 2000; Trombotto et al., 1997). Permafrost and Climate in Europe (PACE). 17 During the late 1990s a series of 100 m deep boreholes were drilled along a transect through the mountains of Europe from the Sierra Nevada in the south to Svalbard in the north (Table 6; Harris et al., 2001; Isaksen et al., 2001). Additional shallow (10 20 m) boreholes were installed adjacent to the deep holes to facilitate detailed investigations of near-surface thermal regimes. The PACE research is focused on prediction of spatial changes in mountain permafrost distribution resulting from climate change, and relating these to potential 17Authors: C. Harris, K. Isaksen, J-L. Sollid, and D. Vonder Mühll.

46 POLAR GEOGRAPHY 211 TABLE 6 Summary of PACE Borehole Sites a Janssonhaugen, Svalbard, Norway Tarfala, Lapland, Sweden Juvvasshoe, Jotunheimen, Norway Schitthorm, Berner Oberland, Switzerland Passo Stelvio, Lombardia, Italy Murtel-Corvatsch Oberengadin, Switzerland Stockhornplateau Wallis, Switzerland Pico/Corral del Veleta, Sierra Nevada, Spain Site description Latitude N N N N N N N N Longitude E E E E E E E E Elevation 275 m 1540 m 1894 m 2900 m 3000 m 2670 m 3410 m 3371/3106 m Topography Hill Ridge Plateau Slope Summit Rock glacier Plateau on crest Ridge/Rock glacier MAAT 8 C (est.) 7 C (est.) 4 C (est.) 3.7 C ( ) -5.5 C (est.) First borehole Drilling date / Depth 102 m 100 m 129 m 101 m m 62 m m 100 m Second borehole Drilling date Depth 15 m 15 m 20 m 14 m 31 m m Meteorostation Installation date Sensors Air temperature Air temperature Air temperature Air temperature Air temperature Air temperature Air temperature Rel. humidity Rel. humidity Rel. humidity Rel. humidity Rel. humidity Rel. humidity Rel. humidity Wind speed Net radiation Net radiation Net radiation Net radiation Net radiation Wind direction Snow depth Snow depth Snow depth Snow depth Snow depth Wind speed Wind speed Wind speed Wind speed Wind speed Wind direction Wind direction Wind direction Wind direction Wind direction Responsible Partner Institute University of Oslo University of Stockholm Team leader Prof. J.-L. Sollid Prof. P. Holmlund University of Oslo VAW-ETH Zürich 3rd University of Rome Prof. J.-L. Sollid Dr. D. Vonder Mühll University of Zürich University of Giessen University Complutense, Madrid Prof. F. Dramis Prof. W. Haeberli Prof. L. King Dr. D. Palacios a Modified from Harris et al., 2000.

47 212 BROWN ET AL. TABLE 7 Mean Active-Layer Thickness (cm/m) for Central Asian CALM Sites a Site number and name CHINA Northeast CN1 Yutulihe TBA Qinghai-Tibet Plateau CN2 Fenghuo Shan CN3 Ecology Station CN4 Wuli 2.6 CN5 Lower Two Rivers 102 CN6 Upper Two Rivers n.d. CN7 Kunlun Basin n.d. Tien Shan CN8 Glacier Station n.d. CN9 Da Xi Gou n.d. CN10 Deep Borehole n.d. CN11 Shallow Borehole n.d. KAZAKHSTAN (N. Tien Shan) K0 Cosmostation K1 Cosmostation K2 Cosmostation TBA MONGOLIA M1 Baganuur, Khentei Mts M2A Nalaikh Depression M2B Nalaikh Depression M3 Argalant Valley M4A Burenkhan Mountain 3.45 M4B Burenkhan Valley 3.25 M5 Ardag Mountain M6A Terkh Valley M6B Terkh Valley 3.50 M7A Chuluut Valley M7B Chuluut Valley 2.40 aall observations based on interpolated active layer values. For Mongolia closely spaced soil temperature measurements rounded to nearest 0.05 m; other observations interpolated to nearest 0.1 m for >2 m; n.d. = no data; TBA = to be added; see Appendix 3 for responsible site individual(s).

48 POLAR GEOGRAPHY 213 increases in slope hazards associated with thawing of frozen ground. Permafrost temperatures are observed in boreholes located throughout the glaciated alpine regions of Europe. A standard borehole and thermal monitoring design was developed as part of PACE. All boreholes are lined with plastic tubing and instrumented with standard thermistor strings assembled by F. Stump AG, Nänikon, Switzerland. Negative temperature coefficient thermistors (Yellow Springs Instruments 44006) with a relative accuracy of 0.02 C are placed on a Colorflex CY chain at depths of 0.2, 0.4, 0.8, 1.2, 1.6, 2, 2.5, 3, 3.5, 4, 5, 7, 9, 10, 11, 13, and 15 m within the shallow boreholes. Within the deep boreholes, additional sensors are placed at 20, 25, 30, 40, 50, 60, 70, 80, 85, 90, 95, 97.5, and 100 m. Active-layer thicknesses are interpolated from the closely spaced themisitors at the time of maximum thaw penetration. These boreholes provide the opportunity to follow changes in the active layer and uppermost permafrost temperatures. The longest record available is from a pre-pace, intensively studied Swiss site at the Murtèl-Corvatsch rock glacier (CH 1; 2670 m a.s.l.; Haeberli et al., 1998; Vonder Mühll et al., 1998). Temperature measurements in a 60 m deep borehole drilled in 1987 provide an excellent time series for the period of record ( ). Figure 19 displays the time series at depths of 3.6 m and 20.6 m. Between 1987 and 1994, the uppermost 25 meters warmed rapidly, with a 0.4 C rise at 20.6 m in four years ( ). This was followed by cooling as a result of thin snow cover. Interpolated active-layer depth remained relatively constant at between 3.1 and 3.5 m, with shallow thaws of 3.1 and 3.2 m occurring in 1995 and 1996, respectively. Temperature at the 20.6 m depth has cooled over the last several years. This study reconfirmed that early winter snow conditions exert an important influence on permafrost temperatures. At Schilthorn (CH2; 2900 m a.s.l.) surface conditions are completely different than at Murtèl-Corvatsch. Dark limestone schists, with a lack of coarse blocks and a lower ice content, cause a thick active layer of up to almost 5 m. Measurements have been obtained since November Both boreholes (Murtèl- Corvatsch and Schilthorn) are now part of the newly established Permafrost Monitoring Switzerland (PERMOS). Several new Scandinavian boreholes are located at Juvvasshoe (N2), southern Norway (1894 m a.s.l.); Tarfalaryggen, northern Sweden (1550 m a.s.l.); and Janssonhaugen (N1) in Svalbard (Table 4). Both the Juvvasshoe and Tarfalaryggen boreholes reveal thermal anomalies that reflect a surface warming over the past decades. The Svalbard site (N1) shows near-surface warming of 1.5 ± 0.5 C during the 20th century (Isaksen et al., 2000). Additional PACE boreholes in Italy, Spain, and Switzerland will report interpolated active-layer thicknesses in the future. Canadian Rocky Mountains. 18 A series of mountain permafrost boreholes were established starting in the early 1970s in the Canadian Cordillera (Harris, 1990, 2001). Ten sites have been monitored, including Plateau Mountain and Marmot Mountain in Alberta, and Summit Lake in British Columbia. The Plateau Mountain site was first used to establish the presence of permafrost in the mountains of southwestern Alberta. For this initial report, only the Marmot Basin #2 site (C21) is reported and is based on data obtained from the 1979 bore hole drilled to a depth of 16.8 meters and located just above tree line. Permafrost up to 6.8 m thick was present 18Author: S. A. Harris.

49 214 BROWN ET AL. Fig. 19. Borehole temperatures from the Murtel-Corvatsch rock glacier ( ). for almost the entire period, with the active layer ranging between 2.2 and 4.3 m in depth. Permafrost temperature varied seasonally, ranging down to 2.5 C. The water table lies at about 12 m depth. Mean annual air temperature ( ) is 2.38 C; but there has been a gradual decrease of 0.7 C during the period. Snowfall has increased gradually to 330 cm since The thermal profile shows warming at times from both the bottom and top, and in 1998 the entire section thawed briefly. Snow cover and ground temperatures show a better qualitative correlation than do air and ground temperatures. As observed in other mountainous and warm permafrost regions, a thin or late winter snow cover permits greater ground heat loss; conversely, early and deep snow results in less winter heat loss. Interannual active-layer thickness is highly variable and is not correlated with thawing index as is the case at many arctic sites reported. Complex processes of conductive and convective heat flow are responsible for these variable ground temperature regimes and active-layer thicknesses. In spring, warm melt water from the snow pack on the adjacent slope above the site penetrates the soil, occasionally causing complete perforation of the permafrost. The talik is very short-lived, as illustrated in Table 3 (1998) with the refreezing of the talik zone and a subsequent reduced thaw presumably in the absence of warm meltwater. The complexity of processes affecting the thickness of the active layer at a given site in mountains suggests that multiple study sites related to different parts of the alpine landscape are required. Several new CALM grids recently were established in the Yukon by A. Lewkowicz, including a 100 m grid in 1999 at the southern end of Kluane Lake (Table 3, Appendix 1). Kazakhstan. 19 Monitoring of permafrost temperature and active-layer thickness began in the Transili Alatau Range (the front range of the Northern Tien Shan) in 19Authors: A. P. Gorbunov and S. S. Marchenko.

50 POLAR GEOGRAPHY (Gorbunov, 1996). Three distinct landscape zones characterize the upper northern slopes: coniferous tree zone ( m a.s.l.); subalpine and alpine meadows ( m); and glacial-nival (above 3500 m). The level of the 0 C annual mean air temperature is located between 2650 and 2700 m. The maximum annual precipitation is about 1500 mm at 3400 m in the central part of the Range, with precipitation decreasing to the east and west. Continuous permafrost zone occurs above 3600 m; discontinuous permafrost is limited to m; and sporadic permafrost to m. Small permafrost islands are found locally as low as 1800 m. Active-layer thickness is determined by temperature measurements made in boreholes from 3 m up to 70 m in depth. Several CALM sites are located in the Transili Alatau Range in the discontinuous permafrost lower zone at 3325 to 3337 m (Table 7). The permafrost here is very sensitive to environmental changes. The deeper boreholes were drilled in in the vicinity of Zhusalykezen Mountains Pass in Upper Pleistocene and Holocene moraines. Excavations in the moraines revealed massive, syngenetic cryogenic textures (15 20 cm thick ice lenses) at depths below 4.5 to 5.0 m, with ice volumes of 5 to 40 percent. Depending on geology and microclimatic conditions, the thickness of permafrost varies from 10 to 80 m across distances of 100 to 150 m on north-facing slopes and is absent on southern slopes. During the period , the permafrost temperature was 0.4 C to 0.8 C and active-layer thickness was 3.0 to 3.5 m. Starting in 1997, thermistor sensors with loggers were installed to a maximum depth of 4.6 m. Air temperatures from high-mountain weather stations in the Tien Shan indicate a rise in summer, winter, and annual air temperatures during the 20th century. The average increase in mean annual air temperature for the last 120 years in the Northern Tien Shan has been C/yr. Geothermal observations at an altitude of 3330 m indicate a rising trend in the permafrost temperature for the last 27 years. The permafrost temperatures increased during the period from 0.2 to 0.3 C for natural systems and up to 0.6 C under disturbed sites (Marchenko, 1999). The rise in summer and winter air temperature and precipitation result in an increase of 30 percent in the active-layer thickness. A residual thaw layer between 5 and 8 m in depth at different sites has appeared. At the CALM site K1 (3328 m), the mean annual temperature at a depth of 4.6 m increased from 0.21 C in 1998 to 0.82 C in This warming was accompanied by a rise of summer and winter air temperature, and also by hydrological changes involving deeper penetration of runoff and summer precipitation. Permafrost also is warming in the Inner Tien Shan (41 50' N and 78 10' E). During the period , observations were carried out in 20 boreholes in the Ak- Shiyrak massif (between 4000 and 4200 m a.s.l.), and in more than 25 boreholes in the Kumtor valley (between 3560 and 3790 m). Permafrost temperatures at depths of m vary from 0.6 C to 2.6 C in the valley bottom and from 1.6 C to 6.7 C on the western slopes of Ak-Shiyrak massif. Permafrost thickness varies from 35 to 130 m in the valley and reaches 350 m on the western slopes. Permafrost temperatures increased by 0.1 C for the period in both in the valley and mountain massif. Although there are no systematic long-term active-layer measurements, individual years varied from 0.5 to 2.5 m, depending on altitude, slope, aspect, and geomorphology. Data from the Tien Shan weather station (3614 m) indicate that the mean annual air temperature has increased by 0.5 C from 1930 to 1988, and is currently 7.8 C.

51 216 BROWN ET AL. Mongolia. 20 Permafrost zones occupy almost two-thirds of Mongolia, predominantly in the Khentei, Hovsgol, Khangai, and Altai mountains and surrounding areas. The territory is characterized by mountain and arid land permafrost, and is sporadic to continuous in extent in the southern fringe of these Siberian permafrost zones. Most of the permafrost is at temperatures close to 0 C, and is therefore thermally unstable under the influence of climate warming and technogenic activities. In the continuous and discontinuous permafrost zones, taliks are found only on steep south-facing slopes, under large river channels and deep lake bottoms, and along tectonic fractures with hydrothermal activity. In areas of isolated permafrost, frozen ground is found only on north-facing slopes and in fine-grained and moist deposits. The lower limit of continuous permafrost on south facing slopes ranges in elevation from 1400 to 2000 m in the Hovsgol and Khentei Mountains, and occurs between 2200 and 3200 m in the Altai and Khangai Mountains. The lowest limit of sporadic permafrost is found between 600 and 700 m. Average thickness and temperature of continuous permafrost is 50 to 100 m and 1 to 2 C in valleys and depressions, and 100 to 250 m and 1 to 3 C in mountains, respectively. Permafrost in Mongolia is characterized mainly by low and moderate ice content in unconsolidated sediments. Ice-rich permafrost is characteristic of lacustrine and alluvial sediments in valleys and depressions. Thickness of active layers are 1 3 m in fine-grained soils and 4 6 m in coarse material or at sites with mean annual ground temperatures of close to 0 C. Mean annual ground temperatures in the Selenge Basin increased at rates of 0.01 to 0.02 ºC per year and permafrost degradation is occurring across 75 percent of the region where permafrost exists (Sharkhuu, 1998). However, permafrost in the taiga zone of the Khentai Mountains is aggrading under dense forests where moss is present. If the present warming rates continue, permafrost with thicknesses of 15 to 20 m will disappear by the middle of the 21st century. This would represent a reduction of permafrost occurrence from percent to 20 percent of the Selenge Basin. Active-layer thickness and permafrost temperature have been measured at mountainous locations in Mongolia since 1976 (Sharkhuu, 1998). At present, seven CALM sites with 11 boreholes exist in the Khentei, Hovsgol, and Khangai mountain regions. The CALM program includes measurements in boreholes drilled 10 to 25 years ago, new sites (Baganuur, Nalaikh, and Argalant, M1-M3) in the Khentei Mountains, three old deep (Burenkhan and Ardag, M4, M5) boreholes in Khubsgul Mountains, and four new shallow (Terkh and Chuluut, M6, M7) holes especially instrumented for CALM (Table 7). All the sites are accessible by surface transportation. Three new CALM sites are in the process of being installed: (1) in glacial deposits at an elevation of 2500 m near Khar Lake in the Altai Mountains; (2) at the Khatgal weather station near Hovsgol Lake, where permafrost temperature measurements in a 10 m deep borehole were made from 1983 to 1987; and (3) in the intermountain depression of the arid steppe zone, 135 km south from Ulaanbaatar where in 1978 the southern limit of permafrost was determined by temperature measurements. The method for carrying out the CALM program in Mongolia is based on longterm temperature monitoring or repeated measurements in boreholes obtained in late September or early October. Active-layer thickness is determined by interpolation of borehole temperature profiles. Boreholes are both cased and uncased. Ground 20Author: N. Sharkhuu.

52 POLAR GEOGRAPHY 217 temperatures are measured using MMT-4 type thermistors and MB 400 type digital multimeter. In addition to temperature measurements, thaw tubes are used at CALM sites at Nalaikh and Baganuur. Starting in July and September 2000, temperature data loggers were installed in two boreholes at Nalaikh and Terkh. In general, ground thawing starts in the middle of April and refreezing begins in October. However, there is a great difference in active-layer thickness and length of the thaw season. Active-layer thicknesses are 3.4 m in Nalaikh and 6.1 m at the Argalant site. Maximum thickness and complete refreezing are observed in early October and early December in Nalaikh, and in December and early February in Argalant, respectively. Trends of air temperatures for the period in various parts of Mongolian territory show that mean summer temperatures in the Selenge River basin, embracing central Mongolia, have increased by only 0.5 C, whereas winter temperatures have increased by 4.0 C in the past 50 years. During the past 50 years, annual mean air temperatures have increased by 1.8 C in western Mongolia, 1.4 C in central Mongolia, and 0.3 C in southern and eastern Mongolia. During the past 50 years, trends of mean summer, winter, and annual precipitation have not changed significantly. According to data from the Baruun Kharaa weather station, located about 120 km northwest from Ulaanbaatar, the trend of mean annual air temperatures ( C) for the period and are and per year (0.089 and in winter, 0.0 and in summer, respectively). Annual mean air temperatures were 0.2 C in 1996, 0.3 C 1997, 1.1 C in 1998, and 0.1 C in Data from various mountain regions of Mongolia obtained by temperature measurements during the last five years, as compared to those measurements observed years ago, show similar changes in active-layer thickness. The average annual thickness of active layers increased by cm in Khentei, by cm in Khubsgul, and by cm in the Khangai mountain regions. The lowest changes in active-layer thickness are observed in the continuous and discontinuous permafrost area rather than in sporadic and isolated zones, in ice-rich and fine-grained sediments, rather than in low-ice and coarse materials or bedrock, and on north-facing slopes as opposed to south-facing ones. The annual range of changes in the thicknesses is 3 10 cm and maximum cm in boreholes with deep thaw or bedrock. According to data from the Baruun Kharaa weather station, mean annual and summer air temperatures during the last five years were at a maximum in 1998, and recent changes are greater than the trend observed during the last 60 years. During the last five years, maximum depth of seasonal ground thaw for all boreholes was observed in 1998 and minimum depth primarily in China. 21 Within the past several years a series of soil climate temperature recording stations has been installed on the Qinghai-Tibet Plateau (QTP) and in the Northern Tien Shan in cooperation with the Chinese Academy of Sciences, its Cold and Arid Environmental and Engineering Research Institute (CAREERI) in Lanzhou, the U.S. Department of Agriculture, and University of Alaska-Fairbanks (Table 7). Initial results for the Plateau stations indicate active-layer thickness between 100 and 260 cm. The one reporting CALM site in northeast China has an interpolated active- 21Authors: Liu Futao, R. F. Paetzold, C. L. Ping, and Zhao Lin.

53 218 BROWN ET AL. TABLE 8 Mean Active-Layer Thickness (cm) for Selected Sites in the Antarctic a Site number and name A1 Scott Base (NZ/US) A2 Bull Pass (NZ/US) A3 Marble Point (NZ/US) A4 Beacon Valley (US) TBA TBA A5 Victoria Valley (US) TBA TBA A6 Simpson Crags (Italy) TBA TBA A7 Boulder Clay (Italy) TBA A8 Oasi (Italy) TBA a TBA to be added; see Appendix 3 for responsible site individual(s). layer thickness between 96 and 112 cm. The sites installed in 2000 are reported in Table 7 and Appendices 1 and 2, as they will start reporting data in A large number of boreholes have historical temperature measurements and new sites are being established. An excellent synthesis on permafrost and climatic change in China is available (Jin Huijun et al., 2000). The authors state that since the early 20th century significant permafrost degradation has occurred and is occurring in most permafrost regions of China. Substantial retreat of permafrost is expected on the Qinghai-Tibet Plateau (QTP) and in northeastern China during the 21st century. Data presented indicate that active-layer thickness has increased from the 1980s to 1990s on the QTP, and that increases are greater at lower altitudes than in the interior. The GTN-P project is in the process of identifying the existing and proposed boreholes from which a time series of active-layer observations can be established on an international basis. Antarctic 22 A Southern Hemisphere CALM network is under development in cooperation with the Scientific Committee on Antarctic Research (SCAR) project on Regional Sensitivity to Climate Change (RiSCC). A number of soil climate sites have been active over the past several years and qualify as CALM sites. Some metadata and data from these sites have been made available for this CALM report (Table 8, Appendix 1). This brief discussion of soil-active layer measurements is presented as an introduction to the developing Southern Hemisphere active layer/permafrost network (Campbell and Claridge, 1987). Permafrost occurs throughout all of the exposed bare ground surfaces in Antarctica but its investigation has been difficult owing to lack of section exposures and a need for observation mainly by drilling (Bockheim, 1995; Bockheim and Hall, in press). Antarctic permafrost includes massive ground ice, ice-bonded permafrost, and dry frozen permafrost. Massive ground ice occurs where ablation till, sometimes with well-developed soil profiles, overlies stagnant glacial ice that may be several million 22 Authors: J. Aislabie, M. R. Balks, I. B. Campbell, M. Guglielmin, J. M. Kimble, R. F. Paetzold, and R. Sletten.

54 POLAR GEOGRAPHY 219 years old. Ice-rich and ice-bonded permafrost, the most common forms of ground ice, occur on the widespread till-covered glacial retreat surfaces that are distinguished by well-developed patterned ground with associated ice wedge and sand wedge features. Dry permafrost is usually formed in older soils and tills at higher elevations, where there is insufficient soil moisture for cementation. In ice-rich and ice-bonded permafrost, the ice content appears to be climate related, with higher ice contents in the warmer coastal regions and lower ice content in cooler and drier inland regions. The rate of accumulation of ice in permafrost is very slow, judging by differences observed on differing landforms. However, the loss of water from ice-bonded permafrost is rapid following soil and landscape disturbances. Areas with massive ground ice are susceptible to active decay when the soil thermal profile is destabilized. Liquid water is seldom observed but may be present in thin film saline solutions. Summer snowfalls are transient and water is lost from the soil, typically within a few hours. Moisture transfer is probably by way of thin films or as vapor and is likely to be complicated by salt horizons within the soils. Large soil temperature changes through the year (up to 35 C in winter) may be accompanied by soil moisture changes, but the absence of weathered soil within the ice-bonded permafrost seems to imply prolonged ice-cement stability. Surface features, including ground roughness and darkness, are important features that influence the soil thermal properties and therefore the permafrost. The soils are very dry (low heat capacity, but also low thermal conductivity), but have no vegetation to shade the soil surface, no transpiration, and very low evaporation to cool the soil surface. Thus, the incoming solar energy is used almost entirely to heat the soil. Summer daily maximum soil surface temperatures often exceed 20 C. Because the tills and soil materials are always stony, probing to determine thaw depth is not practical in Antarctica, and the measurement of soil temperatures is the most reliable way of determining the annual thaw depth and permafrost depth. In 1999, three permafrost investigation sites were established at sites with differing climatic features in the McMurdo region for continual measurement of temperature and associated climatic parameters (A1 A3). The coastal site on Ross Island has a permafrost table at approximately 35 cm; the second is a drier coastal site at Marble Point with a similar mean annual temperature but where the permafrost table is around 65 cm; and the third is an inland site near Lake Vanda where the permafrost table is at approximately 35 cm, but the soil and permafrost are dry frozen. Three sites are located in Victoria Land (A6 and A7) at Simpson Crags and Boulder Clay (Guglielmin and Dramis, 1999), and a deep bore hole at Oasi (A8). For the Boulder Clay site, the 0 C isotherm was at a maximum depth of 25 cm in 1999, compared to 18 cm in A deep borehole instrumented as part of the Dry Valley Drilling Program (DVDP 11) in the Taylor Valley provides evidence for recent changes in the thermal regime of the permafrost. CONCLUSIONS Observations from the CALM network provide evidence that seasonal soil thaw responds consistently to forcing by air temperature on an interannual basis, in a variety of locations worldwide. Long-term (multi-decadal) records show strong regional synchronicity in active-layer thickness among sites in Alaska, West Siberia, and Scandi-

55 220 BROWN ET AL. navia. Shorter periods of records from northwestern North America also exhibit regional synchronicity. Temporal synchronicity does not, however, extend consistently throughout the circumarctic region, owing to regional differences in climate forcing. Long-term records from Scandinavia, West Siberia, and Alaska highlight several other important points. First, all sites demonstrate significant interannual variation. Long-term records often contain temporal trends that may be correlated with general shifts in atmospheric or oceanic circulation; these trends are visible at regional scales. These relations make interpretation of the general trends in the data difficult when dealing with records of subdecadal length. These observations serve to emphasize the need for standardized, regional collection of long-term measurements in an effort to discriminate spatial and temporal patterns. During the period , some sites in Alaska, northwest Canada, the Nordic region, and Russia experienced maximum thaw depth in 1998 and a minimum in These values are consistent with the warmest and coolest summers. There is consistent evidence for warming, thawing, and subsidence of permafrost in mid-latitude mountains, where permafrost temperatures are relatively warm. Interannual variations in snow cover have a major effect on ground temperatures. Specific conclusions and recommendations include: 1. In the case of Barrow, Alaska the active layer exhibits Markovian-like behavior; the depth of thaw is reset abruptly following summers with extremely large or small degree-day accumulations. Values of average maximum thaw depth in subsequent years cluster around this new level until resetting occurs following the next extreme summer. This phenomenon occurs at irregular intervals involving decadal time scales, and may be present at other sites. 2. At 13 CALM sites along a 1200 km transect of the Mackenzie Valley, maximum annual thaw penetration from the time of installation ( ) to 2000 fluctuated in a complex manner depending on site characteristics, but responded measurably to major climatic events such as the short, cool summer of 1996 north of Norman Wells and the long, warm season of 1998 throughout the valley. The Mackenzie Valley data indicate that increases in thaw penetration can exceed active-layer thickness as a result of melting of excess ground ice and subsequent subsidence. 3. Single-point, interpolated thickness of the active layer based on soil temperature profiles or thaw tubes do not adequately represent the average landscape or grid values. However, they may adequately represent the temporal variability of activelayer thickness at particular points. 4. As observed in Greenland and applicable elsewhere, the best correlation between active-layer thickness and summer air temperature (DDT) is obtained from CALM grids on level ground without summer snow patches. However, small-scale variations, in particular late winter meteorological conditions, exert more control on active-layer development than does the summer air temperature in topographically complex terrain with snow patches. 5. Maximum thaw at forested sites, such as interior Alaska and along the Mackenzie River, do not show a consistent relation to forcing by air temperature, indicating that antecedent snow cover, forest canopy, and ground surface vegetation layer influences could be more important than summer climate.

56 POLAR GEOGRAPHY Maximum active-layer thickness in peaty soils is less varible than adjacent mineral soils. 7. As observed at many CALM sites, large variations in active-layer thickness occur in places relatively close to one another. This fact, as well as the influence of local conditions on the magnitude and rate of thawing, should be considered when developing general schemes and models of active-layer dynamics. Two-stage sampling, in which the first stage is concerned with determining the scale of local variability (Nelson et al., 1999; Gomersall and Hinkel, 2001) and used to inform the second, is highly recommended. 8. The CALM program was to detect and observe the response of the active layer and near-surface permafrost to climate change. Fulfillment of the program s potential requires multi-decadal observations, improved methods of vertical ground control, and additional boreholes for thermal measurements in the upper layers of the permafrost. These goals can be accomplished as part of national programs and international frameworks such as the WMO/FAO GTN-P observing program, but the program s continued success will depend on coordination and synthesis efforts. ACKNOWLEDGMENTS The following is a partial list of sponsors and those providing assistance in the field and office: Alaska, United States. Funding for the core CALM program was provided by National Science Foundation, Office of Polar Programs (OPP , , ) to the University of Cincinnati, and several grants to the Ohio State University, Rutgers University, the State University of New York at Albany, and the University of Delaware (OPP , , , , ). Field equipment and logistical support was provided to sites in Russia, Kazakhstan, and Mongolia. The senior authors are grateful to the Barrow Arctic Science Consortium for administrative assistance and to the Ukpeagvik Inupiat Corporation for access to the Barrow Environmental Observatory. We thank J. D. Fagan, C. Gomersall, A. E. Klene, I. Maximov, L. L. Miller, G. R. Mueller, and N. I. Shiklomanov for their efforts in the field and laboratory over the past six-year period. The ARCSS/CALM grids were conceived and implemented in the 1980s and early 1990s by C. S. Benson, L. D. Hinzman, D. L. Kane, D. A. Walker, J. Brown, and the late K. R. Everett under several programs funded by the U.S. Department of Energy and the National Science Foundation. Ivan Maximov, University of Cincinnati, provided invaluable support in maintaining the CALM web site. The Toolik LTER observations were supported by NSF grants (OPP , DEB and DEB ) to G. Kling at the University of Michigan. Field assistants included M. Costa, B. Harper, K. Judd, J. Laundre, K. Riseng, A. Striegle, and P. Yurista. Sites U4, 6, 7, 8, 9, 11, and were supported by a series of NSF grants (OPP , , , , , , , and ) to the University of Alaska Fairbanks. Data were collected under the supervision of L. Hinzman, V. Romanovsky, and M. Sturm. Field assistants included R. E. Gieck, J. Mendez, J. P. McNamara, A. Monaghan, J. Knudson, J. Drage, B. C. Johnson, P. Overduin, M. Fraver, B. Roys, J. Kasper, N. Sato, A. Hetherington, G. Tipenko, and A. Slater. T. Osterkamp provided earlier unprocessed data ( ) for sites U4, 6,

57 222 BROWN ET AL. and 8. The Tiksi site in Russia was supported partially by Grant EAR University of Washington investigations in the Antarctic were supported by OPP Canada. Logistic support for the Mackenzie Valley sites was provided by the Polar Continental Shelf Project, Natural Resources Canada, Tuktoyaktuk; the Inuvik Research Centre, Aurora Research Institute, NWT; and Water Survey of Canada, Environment Canada in Fort Simpson. Funding was provided by Natural Resources Canada/Geological Survey of Canada, Agriculture and Agri-Food Canada, and Department of Indian and Northern Affairs. Baker Lake data are collected by O. Durey, Science Teacher, Jonah Amitnaaq Secondary School; and additional assistance from Joe Eley, Environment Canada. Funding for data analysis was partially provided by the Government of Canada s Climate Change Action Fund. Field work in the Rocky Mountains was funded by Natural Sciences and Engineering Research Council of Canada operating grants to S. Harris at the University of Calgary and the Department of Geography provided data loggers at Marmot Basin. The Alexandra Fjord site was supported by a grant from the Natural Sciences and Engineering Research Council of Canada, and the Northern Science Training Program, Department of Indian Affairs and Northern Development, Canada, to G. Henry at the University of British Columbia. Field assistants included J. Johnstone, J. Henkelman, D. Bean, K. Breen, E.. Ellis, J. England, M. Svoboda, A. Tolvanen, and A. Young. Logistical support was provided by the Polar Continental Shelf Project, Natural Resources Canada, and the Royal Canadian Mounted Police. China. The USDA NRCS Global Climate Change Program and the National Soil Survey Center supported instrumentation and related support at sites in China. Logistical support for the China stations was provided by the Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences. Denmark. The Zackenberg sites in Greenland were supported by the Danish Research Council s special program for Polar Science and the Commission for Scientific Research in Greenland. The following individuals were involved: M. Rasch, ZERO GeoBasis Program Manager, H. H. Christiansen, S. B. Pedersen, C. Sigsgard, C. Nordstrom, B. Elberling, and O. Humlum. M. Oht collected data at the UNISCALM (Norway). Meteorological data measured at Zackenberg in the period were collected by the ZERO program. The Arctic Station provided the meteorological data from from Qeqertarsuaq for the Disko Island site. Europe. The PACE project was supported by the European Commission Environment and Climate Research programme (DGXII) Contract ENV4-CT For the Janssonhaugen borehole, financial support was provided by the project partners, and by the University Courses on Svalbard. For the Janssonhaugen borehole, financial support was provided by the project partners, and by the University Courses on Svalbard. For the Juvvasshoe borehole, the Norwegian Research Council, University of Oslo, the Norwegian Geotechnical Institute, and the Norwegian Meteorological Institute provided support. New Zealand. Antarctica New Zealand provided logistics support and New Zealand Foundation for Research Science and Technology contributed to funding. The sites are maintained in cooperation with the USDA NRCS Global Climate Change Program and the National Soil Survey Center. Poland. Partial financial support was provided by the Polish Science Research Committee (Grant No 6P04E ).

58 POLAR GEOGRAPHY 223 Russia. The Ayach-Yakha field assistants were Alexander Kalmykov and Eugene Lopatin. Tiksi field studies were supported financially by the Ministry of Education, Culture, Science, Sports, and Technology of Japan. The measurements were assisted by V. Zlobin of the Polar Geocosmophysics Observatory in Tiksi. The NSF OPP grants at the Ohio State University, University of Cincinnati, and SUNY provided partial field support for establishment and data collection at many of the sites. Sweden. The directors and staff of the Abisko Research Station are acknowledged for their continued support. LITERATURE Åkerman, J. Studies on Periglacial Geomorphology in West Spitsbergen, Meddelanden Fran Lunds Universitets Geografiska Institution Avhandlingar, Vol. 89, 1980, pp Åkerman, H. J. Monitoring of the active layer at Kapp Linne, Svalbard, , in: The International Tundra Experiment 6th ITEX Workshop. Ottawa, Canada: University of Ottawa, 1995, 30 pp. Åkerman, H. J. and B. Malmström. Permafrost mounds in the Abisko area, northern Sweden, Geografiska Annaler, Vol. 68A, No. 3, 1986, pp Allard, M., W. Baolai, and J. A. Pilon. Recent cooling along the southern shore of Hudson Strait, Quebec, Canada, documented from permafrost temperature measurements, Arctic and Alpine Research, Vol. 27, No. 2, 1995, pp Alt, B. T. and B. Maxwell. Overview of the modern arctic climate, in: M. Garneaau and B. T. Alt, eds., Environmental Responses to Climate Change in the Canadian High Arctic. Ottawa, Canada: Geological Survey of Canada Bulletin 529, 2000, pp Anisimov, O., B. Fitzharris, J. O. Hagen, R. Jeffries, H. Marchant, F. E. Nelson, T. Prowse, and D. G. Vaughan. Polar Regions (Arctic and Antarctic), in: Climate Change: Impacts, Adaptation, and Vulnerability, the Contribution of Working Group II of the Intergovernmental Panel on Climate Change, Third Assessment Review. Cambridge, UK: Cambridge University Press, 2001, pp Anisimov, O. A. and F. E. Nelson. Permafrost distribution in the northern hemisphere under scenarios of climatic change, Global and Planetary Change, Vol. 14, No. 1, 1996, pp Anisimov, O. A., N. I. Shiklomanov, and F. E. Nelson. Effects of global warming on permafrost and active-layer thickness: Results from transient general circulation models, Global and Planetary Change, Vol. 15, No. 2, 1997, pp Auerbach, N. A., D. A. Walker, and J. Bockheim. Landcover of the Kuparuk River Basin, Alaska. Boulder, CO: Joint Facility for Regional Ecosystem Analysis, University of Colorado, Boulder, 1996, scale 1:500,000. Barry, R. G. Permafrost data and information: Status and needs, in: K. Senneset, ed., Proceedings of the Fifth International Conference on Permafrost. Trondheim, Norway: Tapir Publishers, 1988, pp Barry, R. G., J. A. Heginbottom, and J. Brown. Workshop on Permafrost Data Rescue and Access. Boulder, CO: World Data Center A for Glaciology, 1995, 132 pp.

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61 226 BROWN ET AL. Conference on Permafrost. Ste.-Foy, Canada: Centre d'études nordiques, Université Laval, 1998, pp Golden Software, I. SURFER for Windows User s Guide, Version 7. Golden, CO: Golden Software, Gomersall, C. and K. M. Hinkel. Estimating the variability of active-layer thaw depth in two physiographic regions of northern Alaska, Geographical Analysis, Vol. 33, No. 2, 2001, pp Gorbunov, A. P. Monitoring the evolution of permafrost in the Tien Shan, Permafrost and Periglacial Processes, Vol. 7, 1996, pp Guglielmin, M. and F. Dramis. Permafrost as a climatic indicator in northern Victoria Land, Antarctica, Annals of Glaciology, Vol. 29, 1999, pp Haeberli, W., M. Hoelzle, A. Kääb, F. Keller, D. V. Mühll, and S. Wagner. Ten years after drilling through the permafrost of the active rock glacier Murtèl, eastern Swiss Alps: Answered questions and new perspectives, in: A. G. Lewkowicz and M. Allard, eds., Proceedings of the Seventh International Conference on Permafrost. Ste.-Foy, Canada: Centre d'études nordiques, Université Laval, 1998, pp Harlan, R. L. and J. F. Nixon. Ground thermal regime, in: O. B. Andersland and D. M. Anderson, eds., Geotechnical Engineering for Cold Regions. New York, NY: McGraw-Hill, 1978, pp Harris, C., W. Haeberli, D. Vonder Mühll, and L. King. Permafrost monitoring in the high mountains of Europe: The PACE Project in its global context, Permafrost and Periglacial Processes, Vol. 12, 2001, pp Harris, S. A. Long-term air and ground temperature records from the Canada Cordillera and the probable effects of moisture, in: Proceedings of the Fifth Canadian Conference on Permafrost (Collection Nordicana No. 54). Ste.-Foy, Canada: Centre d'étude nordiques, Université Laval, 1990, pp Harris, S. A. Twenty years of data on climate-permafrost-active layer variations at the lower limit of alpine permafrost, Marmot Basin, Jasper National Park, Canada, Geografiska Annaler, Vol. 83A, No. 1, 2001, pp Henry, G. H. R., ed. The International Tundra Experiment (ITEX): Short-term responses of tundra plants to experimental warming, Global Change Biology, Vol. 3, 1997, pp Hinkel, K. M., J. A. Doolittle, J. G. Bockheim, F. E. Nelson, R. Paetzold, J. M. Kimble, and R. Travis. Detection of subsurface permafrost features with ground-penetrating radar, Barrow, Alaska, Permafrost and Periglacial Processes, Vol. 12, No. 2, 2001, pp Hinkel, K. M. and F. E. Nelson. Spatial and temporal patterns of active layer depth at CALM sites in northern Alaska, , Journal of Geophysical Research-Atmospheres, in press. Hinkel, K. M. and J. R. J. Nicholas. Active layer thaw rate at a boreal forest site in central Alaska, U.S.A, Arctic and Alpine Research, Vol. 27, No. 1, 1995, pp Hinkel, K. M., S. I. Outcalt, and A. E. Taylor. Seasonal patterns of coupled flow in the active layer at three sites in northwest North America, Canadian Journal of Earth Sciences, Vol. 34, 1997, pp

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69 234 BROWN ET AL. APPENDIX 1 Metadata Summaries for Active CALM Sites: Locations, Methods, Thaw Extremes, and DDT a Site PIs b Site code Location Lat. Location Long. Elevation average (m) Methods grid (m) Methods c other Years d of record Minimum e thaw (cm) Maximum e thaw (cm) Degree days thaw (C) f CANADA Mackenzie Valley North Head [3] C N W TT 3, Taglu [3] C N W TT/T/B30 3, > Lousy Point [3] C N W TT/T/B30 3, Parsons Lake [4] C N W 50 T/P Reindeer Depot [3] C N W TT 1, Rengleng River [3] C N W TT 3, Mountain River [3] C N W 39 TT Pump Station [4] C N W 61 T/P Norman Wells [3] C N W TT 3, Great Bear River [4] C N W 93 T/P Ochre River [3] C N W 97 TT Willowlake River [3] C N W 103 TT Fort Simpson [3] C N W TT 2, 8 95 > Rocky Mountains Marmot Basin #2 [41] C N W 2195 T/B talik 929 Kluane Lake [24] C N W T/P TBA

70 POLAR GEOGRAPHY 235 Arctic Islands Alexandra Fjord [1] C N W Lake Hazen [4] C N W 190 T g Tanquary Fjord [24] C N W TT 1 n.a. n.a. 144 g Eureka [24] C N W TT Hudson Bay Region Baker Lake [25] C N W 70 T/B g Sheldrake River [23] C N W TBA T g CHINA Northeast Yutulihe [28] CN N E T TBA Qinghai-Tibet Plateau Fenghuo Shan [39] CN N E 4760 T/B TBA Ecology Station [39] CN N E 4691 T 2 n.a. n.a. 622 Wuli [39] CN N E 4541 T 1 n.a. n.a. 697 Lower Two Rivers [39] CN N E 4601 T/B40 1 n.a. n.a. 636 Upper Two Rivers [39] CN N E 4819 T/B18 TBA n.a. n.a. TBA Kunlun Basin [39] CN N E 4754 T TBA n.a. n.a. TBA Tien Shan Glacier Station [39] CN N E 2131 T TBA n.a. n.a. TBA Da Xi Gou (Glacier Station) [39] CN N E 3549 T TBA n.a. n.a. TBA Deep Borehole [39] CN N E 3505 T TBA n.a. n.a. TBA Shallow Borehole [39] CN N E TBA TBA TBA n.a. n.a. TBA (appendix continues)

71 236 BROWN ET AL. APPENDIX 1 (Continued) Site PIs b Site code Location Lat. Location Long. Elevation average (m) Methods grid (m) Methods c other Years d of record Minimum e thaw (cm) Maximum e thaw (cm) Degree days thaw (C) f DENMARK Greenland Zackenberg ZEROCALM 1 [5] G N W T g Zackenberg ZEROCALM 2 [5] G N W T g Disko Island [5] G N W T g KAZAKHSTAN N. Tien Shan; Cosmostation [26] K N E 3337 T/B g N. Tien Shan; Cosmostation [26] K N E 3328 T/B g N. Tien Shan; Cosmostation [26] K N E 3324 T/B14 3 n.a. n.a. 976 g MONGOLIA Baganuur Depression [35] M N E 1342 TT/T/B g Nalaikh Depression [35] M2A N E 1512 TT/T/B g Nalaikh Depression [35] M2B N ' E 1400 T/B g Argalant Valley [35] M N E 1385 T/B TBA Burenkhan Mountain [35] M4A N E 1705 T/B50 1 n.a. n.a. TBA Burenkhan Valley [35] M4B N E 1478 TT/B10 1 n.a. n.a. TBA Ardag Mountain [35] M N E 1845 T/B15 2 n.a. n.a. TBA Terkh Valley [35] M6A N E 2075 T/2.5 2 n.a. n.a. TBA Terkh Valley [35] M6B N E 2120 TT/B3.6 1 n.a. n.a. TBA Chuluut Valley [35] M7A N E 1870 T/1.7 2 n.a. n.a. TBA Chuluut Valley [35] M7B N E 1855 T/B2.8 1 n.a. n.a. TBA

72 POLAR GEOGRAPHY 237 NORWAY Svalbard Janssonhaugen (PACE) [31] N N E 270 T/102/ (2000) UNIS CALM [37] N N E T 1 n.a. n.a. 441 Norway Juvvasshoe (PACE) [31] N N E 1894 T/129/20 2 n.a. n.a. TBA POLAND Svalbard Calypsostranda [6] P N E 25 P RUSSIA European Tundra Ayach-Yakha [8] R N E T Talnik [32] R N E Bolvansky [33] R N E n.a. n.a. TBA West Siberia Nadym [9A] R N E T/B10 4, Marre Sale [9B] R N E T/B10 6, Vaskiny Dachi [10] R N E T/B g Lena River (Japan) Tiksi [13] R N E T Lower Kolyma River Kuropatochya River [14] R12A,B N ' E T/B15 2 n.a. n.a. 492 h Cape Chukochii [14] R13A N E T/B30 1, h Chukochya River [14] R N E TBA 100 T/B h Konkovaya River [14] R15A,B N E TBA 100 T/B50 1, h (appendix continues)

73 238 BROWN ET AL. APPENDIX 1 (Continued) Site PIs b Site code Location Lat. Location Long. Elevation average (m) Methods grid (m) Methods c other Years d of record Minimum e thaw (cm) Maximum e thaw (cm) Degree days thaw (C) f Segodnya Pingo [14] R N E n.a. n.a. 737 h Akhmelo channel [14] R N E TBA 100 T h Mt. Rodinka [15] R N E TBA 100 T g Lake Glukhoe [14] R N E h Malchilovskaya Channel [14] R N E h Lake Akhmelo [14] R N E T/B h Alazeya River [14] R N E B23 2 n.a. n.a. 792 h Jakutskoe Lake [14] R N E n.a. n.a. 482 h Chukotka Cape Rogozhny [16] R N E T g Mt. Dionisiya [17] R N E T g Lavrentia [32] R N W n.a. n.a. 912 g SWEDEN Svalbard Kapp Linne (peat) [18] S N E T/B Kapp Linne (mineral) [18] S N E T/B Sweden Abisko (peat) [18] S N E T/B g Abisko (alpine) [18] S N E T g

74 POLAR GEOGRAPHY 239 SWITZERLAND Murtel-Corvatsch (PACE) [27] CH N 9 50 E 2670 T/B TBA Schilthorn (PACE) [27] CH N 7 50 E 2900 T/B102/14 2 n.a. n.a. TBA UNITED STATES Arctic Alaska Barrow [19] U N W T Barrow [19] U N W 3 10 T Atqasuk [19] U N W T West Dock [20] U N W T/B56 5, g West Dock [19] U ' N ' W 1000 T g Deadhorse [19] U6A N W g Deadhorse [20] U6B N W 100 T/B g Betty Pingo [19] U N W T g Franklin Bluff [20] U N W T/B60 5, g Happy Valley [20] U N W T/B g Happy Valley [19] U ' N ' W T g Imnavait Creek [19] U N W T g Toolik [19] U N W T Toolik LTER [21] U N W , Galbraith Lake [20] U N W T/B g Chandalar Shelf [20] U N W T/B TBA Old Man [20] U N W T/B TBA Drew Point [30] U N W 5 T/B TBA Inigok [30] U N W 53 T/B TBA (appendix continues)

75 240 BROWN ET AL. APPENDIX 1 (Continued) Site PIs b Site code Location Lat. Location Long. Elevation average (m) Methods grid (m) Methods c other Years d of record Minimum e thaw (cm) Maximum e thaw (cm) Degree days thaw (C) f Fish Creek [30] U N W 31 T/B TBA Awuna [30] U N W 110 T/B TBA Umiat [30] U N W 201 T/B TBA Tunalik [30] U N W 26 T/B TBA Koluktak [30] TBA N W 60 T/B227 2 n.a. n.a. TBA Niguanak [30] U N W 84 T/B30 1 n.a. n.a. TBA Ivotuk [20,34] U26a-c N W /1000 T 3 n.a. n.a Seward Peninsula Council [34] U N W T/B8/9 2 n.a. n.a. 914g Kougarok Subarctic Alaska Wickersham [34] U N W T/B4/5 2 n.a. n.a. 914g [22] U N W 335 P g Bonanza Creek [22] U N W T/B g Pearl Creek [22] U N W 213 TT/P ANTARCTIC Scott Base (NZ/US) [38] A S E 38 T 2 n.a. n.a. TBA Bull Pass (NZ/US) [38] A S E 152 T 2 n.a. n.a. TBA Marble Point (NZ/US) [38] A S E 50 T 2 n.a. n.a. TBA

76 POLAR GEOGRAPHY 241 Beacon Valley (US) [40] A S E 1273 T/B20 2 n.a. n.a. TBA Victoria Valley (US) [40] A S E 450 T 2 n.a. n.a. TBA Simpson Crags (Italy) [36] A S E 830 T/B7.8 3 TBA TBA TBA Boulder Clay (Italy) [36] A S E 205 T/B Oasi (Italy) [36] A S E 80 T/B n.a. n.a. TBA aweb sites for additional CALM, borehole information and data, and links: CALM = < GTN-P = < permafrost>; PACE = < bsee Appendix 3 for contributing authors and site responsible investigator(s). ctt = thaw tube; T = interpolated thaw depth based on temperature profile, generally obtained by data logger at ± 10 cm; B = closest borehole, number is depth in meters; TBA = data being processed and to be added; P = probed (all grids are probed). dfirst number represents years for grid measurements; second value represents number of years of records since measurements started. ebased on at least three years of observations; otherwise not available (n.a.). faverage thaw degree days based on available June, July, and August monthly averages for , unless otherwise indicated as (years). gestimated DDT from closest climate station. hestimated DDT based on gridded monthly mean temperatures for June, July, and August obtained from Cort J. Willmott and Kenji Matsuura (2001), Terrestrial Air Temperature and Precipitation: Monthly and Annual Time Series ( ), Version 1.02, Global Climate Resource Pages,

77 242 BROWN ET AL. APPENDIX 2 Metadata Summaries for Active CALM Sites: Landscapes, Vegetation, and Soils Site Landscape description Vegetation classification a Soils b (or material) CANADA Mackenie Valley North Head Thermokarst coastal plain Low shrub tundra Orthic EutricTurbic Cryosol c Taglu Coastal delta plain High shrub, riparian Regsolic Static Cryosol c Lousy Point Glaciofluvial ridge Low shrub tundra Orthic Eutric Turbic Cryosol c Parsons Lake Reindeer Depot Rengleng River Undulating morainal plain Channel-dominated delta bar Alluival plain at delta apex Medium shrub tundra High shrub, riparian Mixed sprucehardwood Orthic EutricTurbic Cryosol c Regsolic Static Cryosol c Regsolic Static Cryosol c Mountain River Low fluvial terrace Birch-alder thicket Orthic Eutric Static Cryosol c Pump Station Lacustrine plain Open black forest Histic Regosolic Turbic Cryosol c Norman Wells Fluvial terrace on till Mixed spruce forestfeathermoss Great Bear River Alluvial terrace Open black spruce forest Ochre River Fluvial terrace in Mixed black spruce glaciolacustrine plain forest Willowlake River Abandoned fluvial bar White sprucefeathermoss Fort Simpson Glaciolacustrine plain Mixed sprucefeathermoss Rocky Mountains Marmot Basin #2 Bench below steep Moist alpine meadow slope Kluane Lake Southwest slope Dwarf shrubherbaceous meadow Arctic Islands Alexandra Fjord Glacial outwash plain Dwarf shrub heath, dominated by Cassiope Histic Eutric Turbic Cryosol Histic Eutric Turbic Cryosol c Histic Eutric Static Cryosol c Histic Regsolic Static Cryosol c Histic Eutric Turbic Cryosol c Orthic Dystric Brunisol c Orthic Eutric Turbic Cryosol c Orthic Eutric Static Cryosol c Lake Hazen Colluvial plain Broken herb tundra Regosolic Turbic Cryosol c (appendix continues)

78 POLAR GEOGRAPHY 243 Appendix 2 (Continued) Site Landscape description Vegetation classification a Soils b (or material) Tanquary Fjord Raised delta Prostrate shrub zone Regosolic Static Cryosol c Eureka Plateau and upper valley slopes Prostrate shrub zone Hudson Bay Region Baker Lake Raised degraded beach Heath lichen, darf ridges over granite shrub bedrock Sheldrake River Palsa over marine silts d ****** Regosolic Turbic Cryosol c Pergelic Cryochrept e Typic Organic Cryosol c CHINA Northeast Yutulihe ******* ******* ******* Qinghai-Tibet Plateau Fenghuo Shan Alpine meadow Kobrecia grass cover Typic Haploturbel e Ecology Station Alpine steppe, sand dune over lake basin Stipa grass cover Typic Cryopsamment e Wuli Alpine steppe Stipa grass cover Ustic Palecryalf e Lower Two Rivers Alpine meadow; frost cracked mounds Kobrecia grass cover Fluventic Sapristel e Upper Two Rivers Alpine steppe Kobrecia grass cover Ustic Haplocryalf e Kunlun Basin ****** ****** Ustic Eutrocryept e Tien Shan Glacier Station Outwash terrace Grass Fluventic Calciudoll e Da Xi Gou (Glacier Sta.) ******* ******* Ruptic-Histic Aquiturbel e Deep Borehole Glaciated valley Kobrecia grass cover Typic Aquiturbel e Shallow Borehole Glaciated valley Kobrecia grass cover Ruptic-Histic Aquiturbel e DENMARK Greenland Zackenberg ZEROCALM 1 Marine abraded ground Cassiope tetragona moraine heath Zackenberg Fluvial terraces on ZEROCALM 2 raised delta Salix arctica snowbed, fen Disko Island Top of moraine ridge Willows, mosses ******* KAZAKHSTAN Tien Shan; Cosmostation Old moraine near mountain pass No vegetation Typic Psammoturbels e Typic Psammoturbels e (Gravelly till with stone fragments) (appendix continues)

79 244 BROWN ET AL. Appendix 2 (Continued) Site Landscape description Vegetation classification a Soils b (or material) Tien Shan; Cosmostation Tien Shan; Cosmostation MONGOLIA Baganuur Depression Nalaikh Depression Nalaikh Depression Upper slopes near mountain pass Upper slopes near mountain pass Areas of Kobrecia grass Kobrecia grass cover (Gravelly till with stone fragments) (Loam over gravelly [10-20 cm] till) Degrading pingo, lake Dry grassland (Loamy sand and clay) shore North-facing slope (6 ) Grassland steppe with (Loam and sand) herds Pingo (4.5 m) in lake Dry grassland (Lacustrine silt and clay) Argalant Valley Dry valley bottom Meadow grassland with herds Burenkhan Mountain North-facing slope (20 ) Burenkhan Valley Valley bottom Ardag Mountain Southeast-facing slope (20 ) Grassland steppe with herds Grassland steppe with herds Coniferous forest (Gravelly loam) (Limestone with 1 m debris) (Loam and sand) (Slate with 1 m debris) Terkh Valley Floodplain Grassland with herds (Sand and loamy sand) Terkh Valley Dry valley botom Grassland (Gravelly sand) Chuluut Valley Pingo top Grassland (Sand and clay) Chuluut Valley Thermokarst lakeshore Grassland with herds (Gravelly sand and loam) NORWAY Svalbard Janssonhaugen (PACE) UNIS CALM Norway Juvvasshoe (PACE) POLAND Svalbard Calypsostranda [6] RUSSIA European Tundra Ayach-Yakha Mountain top Flat terrace-like loess deposit Mountain plateau Sparse vegetation cover Dominant willow Sparse vegetation cover Raised marine terraces Lichen-moss tundra Glacial marine plain Mesic dwarf shrubmoss tundra with dissected by streams frost boils (In situ weathered bedrock/patchy till) (Laminated silty sand) (Block field, in situ weathered bedrock) Gelic Regosol f Turbi-Histic (Gleyic), Gleyi-Turbic Cryosols (loamy) f (appendix continues)

80 POLAR GEOGRAPHY 245 Appendix 2 (Continued) Site Landscape description Vegetation classification a Soils b (or material) Talnik Bolvansky West Siberia Nadym Marre Sale Vaskiny Dachi Lena River Tiksi Lower Kolyma River Kuropatochya River Cape Chukochii Glacial marine plain Mesic shrub-dwarf dissected by streams shrub-moss-lichen tundra Marine plain dissected Mesic dwarf shrublichen-moss tundra by lakes and streams with frost boils Lacustrine-alluvial plain dissected by lakes and ravines Marine plain dissected by lakes and ravines Fluvial-marine plain dissected by lakes and ravines Floodplain and first terrace Edoma with alas depressions Edoma with alas depressions Chukochya River Edoma with alas depressions Konkovaya River Edoma with alas depressions Wet dwarf shrubmoss-lichen peatland Dry and mesic prostrate dwarf Mesic prostrate dwarf shrub-lichen-shrub moss; shrub-grass tundra Lichen-moss-sedge tundra Mesic sedgecottongrass tundra Mesic sedgecottongrass tundra Mesic dwarf shrubmoss hummocky tundra Mesic sedgecottongrass tundra Segodnya Pingo Sandy plain, lakes Mesic low shrubmoss-lichen polygon tundra Stagnic Cryosol, Stagni-Gelic Cambisol (loamy) f Turbi-Histic (Gleyic) and Gleyi-Turbic Cryosols (stony loam) f Dystri-Cryic and Dystri-Gelic Histosols (sandy) f Dystri-Gelic Gleysols (sandy) and Fibri- Cryic Histosols (clayey) f Gleyic Cryosols (sandy and clayey) f (Gravels) Gleyic Cryosols (loamy) f Oxyaqic Cryosols, (loamy) on Edoma; Gleyic Cryosols (loamy) in the alas f Gleyic Cryosols (loamy) f Gleyic Cryosols (loamy) on Edoma; Gleyi-Histic Cryosols (loamy) and Cryic Histosols in the alas f Haplic and Gleyi-Histic Cryosols (sandy); Cryic Histosols f (appendix continues)

81 246 BROWN ET AL. Appendix 2 (Continued) Site Landscape description Vegetation classification a Soils b (or material) Akhmelo ChannelFloodplain Mesic low shrub Gleyic and Gleyi-Histic Cryosols (loamy); Cryic Histosols f Mt. Rodinka Gentle west-southwest slope Shrub-moss-lichengrass tundra with sparse larch Gleyi-Histic Cryosols (loamy) f Lake Glukhoe Sandy plain with lakes Thin larch forest Turbic Cryosols (sandy) f Malchilovskaya Channel Floodplain Wet low shrubs and forbs Gleyic and Gleyi-Histic Cryosols (loamy); Cryic Histosols f Lake Akhmelo Sandy plain with lakes Mesic low shrub Turbic Cryosols (sandy) f Alazeya River Edoma with alas depressions Low shrub tundra Jakutskoe Lake Edoma with alas Hummocky tundra depressions Chukotka Cape Rogozhny Hilly plain Mesic dwarf shrubcottongrass-moss tussock tundra Mt. Dionisiya Lavrentia SWEDEN Svalbard Kapp Linne (peat) Kapp Linne (mineral) Proluvial-deluvial mountain slope Mesic sedge-dwarf shrub-moss hummocky tundra with cotton-grass tussocks Gentle mountain slope Wet dwarf shrubsedge-moss hummocky tundra Bog between uplifted marine terraces Uplifted marine terrace Moss tundra, hummocks and polygons Lichen-moss tundra Sweden Abisko (peat) Peat plateau Dwarf shrub, lichen, moss tundra Oxiaquic Cryosols (loamy) f Gleyic Cryosols f Gleyi-Histic Cryosols (loamy) f Gleyi-Histic Cryosols (loamy) f Gleyi-Histic Cryosols (loamy) f (Peat over glaciomarine silt and clay) Gelic Regosol, above glaciomarine silt and clay f (Peat, covering glaciolacustrine sand and clay) (appendix continues)

82 POLAR GEOGRAPHY 247 Appendix (Continued) Site Landscape description Vegetation classification a Soils b (or material) Abisko (alpine) Alluival terrace, floodplain, with pingo-like mounds Mosit alpine sedgecottongrass tundra (Thin peat, over alluvial/colluvial sand and gravel) SWITZERLAND Murtel-Corvatsch Rock glacier ******* ******* (PACE) Schilthorn (PACE) Mountain slope ******* ******* UNITED STATES Arctic Alaska Barrow Atqasuk West Dock Deadhorse Betty Pingo Franklin Bluff Outer coastal plain, drained lake basins Inner coastal plain, drained lake basins Outer coastal plain, drained lake basins Outer coastal plain, drained lake basins Outer coastal plain, drained lake basins Inner coastal plain, river terraces Graminoid-moss tundra (wet and moist acidic) Graminoid, moss tundra and tundra and tussock graminoid, erectdwarf-shrub Graminoid-moss tundra (wet nonacidic) Graminoid-moss tundra and graminoid, prostratedwarf-shrub, moss tundra (wet and moist nonacidic) Graminoid-moss tundra and graminoid prostratedwarf-shrub, moss tundra (wet and moist nonacidic) Graminoid-moss tundra and graminoid, prostratedwarf-shrub, moss tundra (wet and moist nonacidic) Typic Histoturbel, Typic Aquiturbel e Typic Psammoturbel, Typic Aquiturbel, Typic Histoturbel e Typic Hemistel e Typic Aquiturbel e Typic Molliorthel, Typic Historthel, Typic Aquorthel e Ruptic-Histic Aquorthel e Happy Valley Unglaciated foothills Tussock-graminoid, dwarf-shrub tundra and low-shrub tundra (moist acidic) Ruptic-Histic Aquiturbel e (appendix continues)

83 248 BROWN ET AL. Appendix 2 (Continued) Site Landscape description Vegetation classification a Soils b (or material) Imnavait Creek Glaciated foothills Tussock-graminoid, dwarf-shrub tundra and low-shrub tundra (moist acidic) Toolik Glaciated foothills Tussock-graminoid, dwarf-shrub tundra and prostrate-dwarfshrub, moss tundra (moist acidic and nonacidic) Galbraith Lake Chandalar Shelf Old Man Broad glaciated mountain valley Glaciated mountain terrace Wide subarctic valley floor Graminoid-moss tundra and graminoid, prostratedwarf-shrub, moss tundra (wet and moist nonacidic) Alpine meadow Wet tussock tundra Drew Point Outer coastal plain Moist-meadow, tussock-tundra complex Inigok Coastal plain Moist-meadow/ tussock-tundra complex Fish Creek Inner coastal plain Moist-meadow, tussock-tundra complex Awuna Umiat Foothill saddle above Awuna R. L. bench above Colville R. Moist-tussock tundra Moist- tussock tundra Tunalik Inner coastal plain Moist-meadow, tussock-tundra complex Koluktak Outer foothills Moist- meadow, tussock-tundra complex Niguanak Coastal plain Moist-sedge, prostrate shrub tundra Typic Histoturbel, Typic Aquorthel e Ruptic-Histic Aquiturbel e Ruptic-Histic Aquiturbel e Ruptic-Histic Aquiturbel e Ruptic Histoturbel e (Silt) (Silt) (Silt) (Silt) (Silt) (Silty sand) (Silty sand) (Sandy clay) (appendix continues)

84 Site Landscape description POLAR GEOGRAPHY 249 Appendix 2 (Continued) Vegetation classification a Soils b (or material) Ivotuk Glaciated foothills Tussock-graminoid, dwarf-shrub tundra Ruptic-Histic Aquiturbel e and low-shrub tundra (moist acidic) Seward Peninsula Council Kougarok Subarctic Alaska Wickersham Bonanza Creek Pearl Creek ANTARCTICA Scott Base (NZ/US) Bull Pass (NZ/US) Marble Point (NZ/US) Beacon Valley (US) Victoria Valley (US) Simpson Crags (Italy) Boulder Clay (Italy) Outwash plain with thermokast Small headwater drainage Foot of long westfacing slope Old terrace, south side Tanana River Flat west-facing valley floor Glaciated lower side slope of a volcanic center Glaciofluvial outwash terrace Glaciofluvial surface, narrow coastal plain Tussock tundra with alder and spruce Tussock shrub tundra Open black spruce forest Open black spruce forest Open black sprucewhite spruce forest Antarctic cold desert Antarctic cold desert Antarctic cold desert Terric Hemistel e Typic Cryaquept, Ruptic-Histic Aquiturbel e Typic Historthel e Typic Historthel e Typic Historthel e ******* Bare ground ******* ******* Bare ground ******* Flat ice-free area Bare ground ******* Flat ice-free area Bare ground ******* (Gravelly sandy loam) (Gravelly loam over silt loam) (Gravelly sand) Oasi (Italy) ******* Bare granite ******* avegetation classification is incomplete and will be refined for a future report. bpredominant soil(s) based on the following soil classifications (materials in absence of soil classification). ccanadian System of Soil Classification (Soil Classification Working Group, 1998). d****** To be added. e U.S. Soil Taxonomy (Soil Survey Staff, 1999). fworld Reference Base for Soil Resources (ISSS Working Group RB, 1998).

85 250 BROWN ET AL. APPENDIX 3 Contributing Authors and Collaborators, Affiliations, and Addresses a Alaska (Table 2) Jerry Brown [U2], International Permafrost Association [jerrybrown@igc.org] Gary Clow [U20-25/29] (30), U.S. Geological Survey, United States [clow@astmnl.wr.usgs. gov] Kenneth Hinkel [U1-3/5/7/10-12] (19), Univ. of Cincinnati, United States [Kenneth.Hinkel@ uc.edu] Larry Hinzman [U26-28] (34), University of Alaska, United States [ffldh@uaf.edu] George Kling [U13] (21), University of Michigan, United States [gwk@umich.edu] James Laundre [U13] (21), Marine Biology Laboratory, United States [jiml@mbl.edu] Ivan Maximov, University of Cincinnati, United States [maximoi@mail.uc.edu] Frederick Nelson [U1-3/5/7/10-12] (19), University of Delaware, United States [fnelson@udel. edu] Vladimir Romanovsky, [U4/6/8-9/14-16/26] (20), University of Alaska, United States [ffver@uaf.edu] Nikolay Shiklomanov, University of Delaware, United States [shiklom@udel.edu] Les Viereck [U17-19] (22), Institute of Northern Forestry, United States [fnlav@uaf.edu] Canada (Table 3) Michel Allard [C17] (23), Laval University, Canada [m.allard@cen.ulaval.ca] Larry Bliss [C2], University of Washington, United States Margo Burgess [C20], Geological Survey of Canada, Canada [burgess@gsc.nrcan.gc.ca] Stuart Harris [C21] (41), University of Calgary, Canada [harriss@acs.ucalgary.ca] Greg Henry [C1] (1), University of British Columbia, Canada [ghenry@unixg.ubc.ca] Lee Kutny [C3-5,7-9,11,13-15], Aurora Research Institute, Canada [lkutny@inuvik.net] Antoni Lewkowicz [C18-19, 22] (24), University of Ottawa, Canada [alewkowi@uottawa.ca] Mark Nixon [C3-5,7-9,11,13-15] (3), Geological Survey of Canada, Canada [mnixon@nrcan. gc.ca] Sharon Smith, Geological Survey of Canada, Canada [SSmith@NRCan.gc.ca] Josef Svoboda [C20] (25), University of Toronto, Canada [jsvoboda@credit.erin.utoronto.ca] Charles Tarnocai [C6/10/12/16] (4), Agric. and Agri-Food Canada, Canada [tarnocaict@em. agr.ca] Nordic and European Countries (Tables 4, 6) Jonas Åkerman [S1-2 ] (18), Lund University, Sweden [Jonas.Akerman@natgeo.lu.se] Hanne H. Christiansen [G1-3] (5), University of Copenhagen, Denmark [hhc@geogr.ku.dk] Charles Harris [PACE], Cardiff University, United Kingdom [harrisc@cardiff.ac.uk] Ole Humlum [N3] (37), The University Courses on Svalbard, Norway [oleh@unis.no] Ketil Isaksen [N1-2], Norwegian Meteorological Institute, Norway [ketil.isaksen@dnmi.no] Janina Repelewska-Pekalowa [P1] (6), Maria Curie-Sklodowska University, Poland [geomorf@biotop.umcs.lublin.pl] Johan Ludvig Sollid [N1-2] (31), Oslo University, Norway [j.l.sollid@ geografi.uio.no]

86 POLAR GEOGRAPHY 251 Daniel Vonder Muehll [CH1-2] (27), Basel Univ., Switzerland unibas.ch] Russia (Table 5) Julia Boike [R7], formerly Alfred Wegener Institute, Germany Dimo Fedorov-Davydov [R13-17/19-22/25], Institute of Photosynthesis and Soils, Russia David Gilichinsky [R13-17/19-22/25] (14), Institute of Photosynthesis and Soils, Russia Stan Gubin [R13-17/19-22/25], Institute of Photosynthesis and Soils, Russia serpukhov.su] Dmitri Karelin [R23/27], Biology Department, Moscow State University, Russia Yuji Kodoma [R8] (13), Hokkaido University, Japan Anatoly Kotov [R9] (16), Permafrost Institute, Russia Marina Leibman [R5] (10), Earth Cryosphere Institute, Russia G.V. Malkova [R24] (33), Earth Cryosphere Institute, Russia Galina Mazhitova [R2] (8), Institute of Biology, Komi Science Center, Russia ib.komisc.ru] Evgeny Melnikov [R1,3-4, 24], Earth Cryosphere Institute, Russia Nataly Moskalenko [R1] (9A), Earth Cryosphere Institute, Russia Vladimir Ostroumov [R13-17/19-22/25], Institute of Photosynthesis and Soils, Russia Alexander Pavlov [R3,4], Earth Cryosphere Institute, Russia Volodya Razzhivin [R11] (17), Komorov Botanical Institute, Russia spb.edu] Martin Sommerkorn [R6], formerly Kiel University, Germany Victor Sorokovikov [R13-17/19-22/25], Institute of Photosynthesis and Soils, Russia issp.serpukhov.su] Alexander Vasiliev [R3] (9B), Earth Cryosphere Institute, Russia Dmitri Zamolodchikov [R23/27] (32), Center for Ecology and Productivity of Forests, Russia Vadim Zlobin [R8], Polar Geocosmophsics Observatory, Russia Sergei Zimov [R18] (15), North-East Science Station, Russia Central Asia (Table 7) Liu Futao [CN1] (28), Changchun Institute of Geography, CAS, China ac.cn ] Sergei Marchenko [K0-2] (26), Institute of Geography, Kazakhstan [permafrost@astel.kz] Ron Paetzold [CN2-10] (39), Department of Agriculture, United States [Ron.Paetzold@ nsscnt.nssc.nrcs.usda.gov] Chien Lu Ping [CN2-10], University of Alaska, United Staes [pfclp@uaa.alaska.edu] N. Sharkhuu [M1-M7] (35), Institute of Geography, Mongolia [Geo-dgv@magicnet.mn] Zhao Lin [CN2-10] (39), Cold and Arid Environmental and Engineering Research Institute, China [linzhao@ns.lzb.ac.cn] Antarctic (Table 8) Jackie Aislabie [A1-3], Landcare Research, New Zealand [AislabieJ@landcare.cri.nz] Megan Balks [A1-3], University of Waikato, New Zealand [m.balks@waikato.ac.nz]

87 252 BROWN ET AL. Iain Campbell [A1-3] (38), Land and Soil Consultancy Services, N.Z. nz] Mauro Guglielmin [A6-8] (36), Italian Antarctic Program, Italy it] Ron Paetzold and John Kimble [CN2-10, A1-3] (38), Department of Agriculture, U.S. [john. Ron Sletten [A4-5] (40), University of Washington a Entry in brackets [ ] indicates site(s) for which person is responsible; number in parentheses following brackets indicates person(s) or PI(s) responsible for data collection and the site(s). See Tables 2 8, and Appendix 1 for site names and PI numbers.

88 POLAR GEOGRAPHY 253 APPENDIX 4 Photographs of Selected Active CALM Sites Plate 1. Alaska Barrow, Alaska (U1) Council, Seward Peninsula (U27) Toolik Lake LTRER, Alaska (U12)

89 254 BROWN ET AL. Plate 2. Interior Alaska and Canada Pearl Creek, Fairbanks, Alaska (U19) Lousy Point, Mackenzie Delta, Canada (C5) Pump Station, Mackenzie Valley, Canada (C10)

90 POLAR GEOGRAPHY 255 Plate 3. Nordic Region Zackenberg, Greenland (G2) Kapp Linne, Svalbard (S1) Abisko, Sweden (S2)

91 256 BROWN ET AL. Plate 4. Russia Ayach-Yakha, European tundra, Russia (R2) Maare Sale, West Siberia, Russia (R3) Vaskiny Dachi, West Siberia, Russia (R5)

92 POLAR GEOGRAPHY 257 Plate 5. Russia Tiksi, Lena River, Russia (R8) Mt. Dionisiya, Chukotka, Russia (R11) Cape Chukochii, Kolyma River coast, Russia (R13A)

93 258 BROWN ET AL. Plate 6. Mountains Cosmostation, Kazakhstan (K0-2) Chuluut Valley thermokarst, Mongolia (M7) Juvvasshoe borehole, Norway (N2)