PART I Terminology. What is mass balance? Background

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Range 1 2 Claridenfirn, Switzerland, 1916 PART I Terminology Background General reference for mass-balance terminology has been Anonymous,1969, J. Glaciology 8(52).

ng and inconsistent and confusing use of terminology new methods, e.g. remote sensing, require update Working group (2008-2012) by International Association of Cryospheric Sciences (IACS) aims to

1 What is mass balance? Regine Hock Claridenfirn, Switzerland, Terminology, Definitions, Units Conventional and reference surface mass balance Firn line, snow line, ELA Glacier runoff Global mass changes Alaska Range 1 2 Claridenfirn, Switzerland, 1916 PART I Terminology Background General reference for mass-balance terminology has been Anonymous,1969, J. Glaciology 8(52). in practice diverging and inconsistent and confusing use of terminology new methods, e.g. remote sensing, require update Working group ( ) by International Association of Cryospheric Sciences (IACS) aims to update and revise Anonymous (1969) and to provide a consistent terminology for all glaciers (i.e. mountain glaciers, ice caps and ice sheets) GLOSSARY OF GLACIER MASS BALANCE AND RELATED TERMS 1914 Cogley, J.G., R. Hock, L.A. Rasmussen, A.A. Arendt, A. Bauder, R.J. Braithwaite, P. Jansson, G. Kaser, M. Möller, L. Nicholson and M. Zemp, 2011, Glossary of Glacier Mass Balance and Related Terms, IHP-VII Technical Documents in Hydrology No. 86, IACS Contribution No. 2, UNESCO-IHP, Paris. Can be downloaded from: massbalanceglossary 3 4

Glacier mass balance Mass balance is the change in the mass of a glacier, or part of the glacier, over a stated span of time: =mass budget t mass imbalance ΔM = Ṁdt Net gain of mass Accumulation

2 Glacier mass balance Mass balance is the change in the mass of a glacier, or part of the glacier, over a stated span of time: =mass budget t mass imbalance ΔM = Ṁdt Net gain of mass Accumulation area: acc > abl t 1 SPACE: study volume needs to be defined mass balance is often quoted for volumes other than that of the whole glacier, for example a column of unit cross section important to report the domain! TIME: the time period (esp important for comparison with model results) mass change can be studied over any period often done over a year or winter/summer seasons --> Annual mass balance (formerly Net ) Firn line Long-term ELA Net loss of mass Δmb= c+ a = (ċ+ a) dt ACCUMULATION, (c, C) Snow fall Deposition of hoar, freezing rain Windborne blowing snow/ drifting snow Avalanching t t 1. ΔM = ABLATION (a, A) Melting Sublimation Loss of windborne blowing snow/drifting snow Avalanching Calving... t t 1 Ṁdt Ablation area: acc < abl Equilibrium line: acc = abl Mass balance components: It s more than snowfall and melt 5 Mass balance components Precipitation - Surface accumulation precipitation includes rain; rain water is not accumulation; water is not considered to be part of the glacier 6 Accumulation - Net accumulation - Net acc is a balance, acc is not Cogley, J.G., R. Hock, L.A. Rasmussen, A.A. Arendt, A. Bauder, R.J. Braithwaite, P. Jansson, G. Kaser, M. Möller, L. Nicholson and M. Zemp, 2011, Glossary of Glacier Mass Balance and Related Terms, IHP-VII Technical Documents in Hydrology No. 86, IACS Contribution No. 2, UNESCO-IHP, Paris. Cogley, J.G., R. Hock, L.A. Rasmussen, A.A. Arendt, A. Bauder, R.J. Braithwaite, P. Jansson, G. Kaser, M. Möller, L. Nicholson and M. Zemp, 2011, Glossary of Glacier Mass Balance and Related Terms, IHP-VII Technical Documents in Hydrology No. 86, IACS Contribution No. 2, UNESCO-IHP, Paris. 7 8

3 Winter balance <--> accumulation Summer balance <--> ablation What is measured in ice cores? Mass balance components Precipitation - Surface accumulation precipitation includes rain; rain water is not accumulation; water is not considered to be part of the glacier Accumulation - Net accumulation - Net acc is a balance, acc is not Melt - meltwater runoff Melt water may refreeze and does not contribute to meltwater runoff B a = B w +B s = Acc + Abl B w = Accw B s = Ablw Implications for comparison of field measurements with model results? C, A can be modeled, but what is measured often is Bw, Bs 9 Mass balance components Greenland Melt vs. water runoff Gt/yr freezing Meltwater runoff - Runoff Runoff includes rain water Cogley, J.G., R. Hock, L.A. Rasmussen, A.A. Arendt, A. Bauder, R.J. Braithwaite, P. Jansson, G. Kaser, M. Möller, L. Nicholson and M. Zemp, 2011, Glossary of Glacier Mass Balance and Related Terms, IHP-VII Technical Documents in Hydrology No. 86, IACS Contribution No. 2, UNESCO-IHP, Paris. 10 What is mass balance? Mass balance of a column c sfc Precip LAYERS surface a sfc Melt internal ρ snow? compressible? ρ firn? Runoff Tide gauges Surface mass balance h q in a i c i q out basal Ettema et al., 2009, GRL c b a b

What is mass balance? Mass balance of a column c = accumulation a = ablation Δmb= c sfc + a sfc + c i + a i + c b + a b + q in + q out What is mass balance?

Surface internal basal flux divergence Continuity equation Thickness change Mass balance?. ḣ = ḃ Q q in Surface internal basal SMB?

water runoff 100-150 Gt/yr freezing Climatic balance Tide gauges Surface mass balance Ettema et al.

4 What is mass balance? Mass balance of a column c = accumulation a = ablation Δmb= c sfc + a sfc + c i + a i + c b + a b + q in + q out What is mass balance? Mass balance of a column c = accumulation a = ablation Δmb= c sfc + a sfc + c i + a i + c b + a b + q in + q out Surface internal basal flux divergence surface Surface internal basal flux divergence Continuity equation Thickness change Mass balance?. ḣ = ḃ Q q in Surface internal basal SMB? q out q in internal basal q out. ḣ = ḃ Q Climatic balance, bclim Climatic-basal balance, b (Total) mass balance, Δm Surface mass balance Greenland Melt vs. water runoff Gt/yr freezing Climatic balance Tide gauges Surface mass balance Ettema et al., 2009, GRL Precip Melt Runoff GPS What do you measure with GPS vs with a stake? Stake Δmb= c sfc + a sfc + c i + a i + c b + a b + q in + q out Surface internal basal flux divergence Climatic balance Climatic-basal balance (Total) mass balance. ḣ = ḃ Q 15 16

GPS What do you measure with GPS vs with a stake?

b + q in + q out Surface internal basal flux divergence Climatic balance Climatic-basal balance (Total) mass balance Stake.

5 GPS What do you measure with GPS vs with a stake? Δmb= c sfc + a sfc + c i + a i + c b + a b + q in + q out Surface internal basal flux divergence Climatic balance Climatic-basal balance (Total) mass balance GPS What do you measure with GPS vs with a stake? Δmb= c sfc + a sfc + c i + a i + c b + a b + q in + q out Surface internal basal flux divergence Climatic balance Climatic-basal balance (Total) mass balance Stake. ḣ = ḃ Q Stake GPS --> total mass balance (but partitioning in components unknown) Stake --> only surface mass balance, measurement relative to top of the stake What do you measure with GPS vs with a stake? Calving flux only includes mass loss due to calving BUT: >50% of the mass loss at the glacier front can be due to submarine melting (even if grounded) ---> frontal ablation GPS Point/part of glacier Glacier-wide mass loss at the glacier front (includes calving, submarine melting, arial melt/ sublimation...) Interpolating point data over entire glacier Stake GPS --> total mass total mass balance balance --> geodetic balance Stake --> only surface total mass balance mass balance, (for land-terminating noncalving glaciers) measurement relative to top of the stake What is ice discharge? Mass flux or volumetric flux of ice through a glacier crosssection or gate. The gate can be anywhere on the glacier, but is often at the glacier terminus

Mass balance components: It s more than snowfall and melt Email May 2016 But I want to get away from Winter and Summer balance and replace them with Accumulation and Ablation Balance.

6 Mass balance components: It s more than snowfall and melt May 2016 But I want to get away from Winter and Summer balance and replace them with Accumulation and Ablation Balance. For most Alaskan glaciers snow accumulation at higher altitudes occurs throughout the year and can be especially heavy in August and September. ZBA (zero-balance altitude) Total mass budget: sum of climatic-basal balance and frontal ablation Cogley, J.G., R. Hock, L.A. Rasmussen, A.A. Arendt, A. Bauder, R.J. Braithwaite, P. Jansson, G. Kaser, M. Möller, L. Nicholson and M. Zemp, 2011, Glossary of Glacier Mass Balance and Related Terms, IHP-VII Technical Documents in Hydrology No. 86, IACS Contribution No. 2, UNESCO-IHP, Paris Ablation area Accumulation area Time systems: Annual mass balance, i.e. balance over (roughly) one year stratigraphic system fixed-date system floating-date system combined system fixed-date system Winter Summer fixed-date system Winter stratigraphic system Summer End winter snow probing: What system? Stratigraphic system: dates are unknown fixed-date system

7 Time Systems of Annual Measurements of Mass Balance Reported to World Glacier Monitoring System WGMS (Cumulative to 2008) No information provided 1519 Fixed-date system 917 Stratigraphic system 931 Combined system 265 Other 188 Total of reported annual measurements > comparing observations with model results problematic if time system not known What is specific mass balance? 1. The mass balance at a specific location? 2. The mass balance of the entire glacier? 3. The mass balance expressed in m w.e.? Definition: Mass balance expressed per unit area, that is, with dimension [M L 2 T 1 ] or [M L 2 ] often kg m 2 or m w.e. The prefix specific is not necessary. The units make clear whether or not it is specific. Specific mass balance may be reported for a point on the surface (if it is a surface mass balance), a column of unit cross-section, or a larger volume such as the entire glacier. Balances reported for a point are always specific Mass-balance units Mass balance = Mass change over stated period of time Mass [M] kg, Gt (=10 9 kg, 1 billion tonnes) mass change per unit area [M L -2 ] --> kg m -2 (specific unit) m or mm water equivalent (w.e.): -> 1 kg of water (density 1000 kg m -3 ) has thickness of 1 mm when distributed over 1 m 2 -> kg m -2 and mm are numerically identical -> 1 m w.e. = 1000 kg m -2 / density of water m 3 w.e. or km 3 w.e. (1 km 3 w.e. = 1 Gt) --> important to add w.e. or i.e. (ice equiv.) Sea-level equivalent: kg m -2 x glacier area /-(density of water x area of the ocean) (362x10 6 km 2 ) m w.e. a -1 Black Rapids Glacier Mass balance time series look different in different units Gt a -1 by Christian Kienholz 27 28

8 Mass balance time series look different in different units PART II Concept of conventional and reference surface balance Black Rapids Glacier Claridenfirn, Switzerland, 1916 m w.e. a -1 Gt a -1 by Christian Kienholz Mass balance as climate indicator? 30 Glaciers are indicators of climate change? B=V / A Stable climate B a = 0 Steady-state Step change in climate B a < 0 Glacier retreat Stable climate B a = 0 Steady-state conventional mass balance glacier area/hypsometry is updated annually reference surface balance glacier area/hypsometry is kept constant Harrison, W., Elsberg, Cox and March, Different balances for climatic and hydrological applications. J. Glaciol., page 176. This paper is in your folder! 31 32

Conventional mass balance Time 1 (t1) Time 2 (e.g. 50 yrs later) b=measured point balances Mass balance as climate indicator?

purposes da t1 B = 1 b (h1) da B = 1 b t1 (h1) A A t1 t1 Note also the surface elevation changes 33 Which unit to use?

e Conventional balance: Relevant for hydrological purposes b =measured point balance at t2 on surface at t2 but adjusted to surface at t1 Often expressed in the

9 Conventional mass balance Time 1 (t1) Time 2 (e.g. 50 yrs later) b=measured point balances Mass balance as climate indicator? Measurement sites Relevant for hydrological purposes B = 1 A t1 b (h1) da t1 B = 1 A t2 b (h2) da t2 Reference surface mass balance Relevant for climatological purposes da t1 B = 1 b (h1) da B = 1 b t1 (h1) A A t1 t1 Note also the surface elevation changes 33 Which unit to use? kilogramme (kg), or gigatonne (Gt; 1 Gt = 1012 kg). m 3 w.e. or km 3 w.e Conventional balance: Relevant for hydrological purposes b =measured point balance at t2 on surface at t2 but adjusted to surface at t1 Often expressed in the units kg m -2 = specific mass balance 1 kg m -2 = 1 mm of water equivalent, mm w.e. (because 1 kg of liquid water, of density 1000 kg m -3, has a thickness of exactly 1 mm when distributed uniformly over 1 m 2 ) Reference surface balance: Relevant for climatological purposes 35 Stable climate B n = 0 Steady-state Climate change B n < 0 Glacier retreat Stable climate B n = 0 Steady-state Reference surface mass balance does not go to 0 34 Mass-balance feedback: Two opposing Radic Retreat effect Glacier stabilizing glacier retreat increased thinning 36 glacier retreat Thinning effect (Bodvardsson, 1955) destabilizing increased thinning

PART III Firn line, equilibrium line, snow line.

2009, Ann. Glaciol. 37 Truessel et al. 2015, Ann.

1914 37 Snow line Boundary separating snow from

Equilibrium line altitude (ELA) Equilibrium line

where the climatic mass balance is zero at a

10 Conventional vs. reference surface mass balance Yakutat Icefield PART III Firn line, equilibrium line, snow line... Claridenfirn, Switzerland, 1916 Harrison et al. 2009, Ann. Glaciol. 37 Truessel et al. 2015, Ann. Glaciol Snow line Boundary separating snow from ice or firn at any time t Transient - Annual 38 Equilibrium line altitude (ELA) Equilibrium line The set of points on the surface of the glacier where the climatic mass balance is zero at a given moment. The equilibrium line separates the accumulation zone from the ablation zone. Transient - Annual 39 Approximate ELA 40

FIRN Wetted snow that has survived one summer without being transformed to ice FIRN LINE FIRN LINE can be seen on radar profiles Snow surface Mass

above) from glacier ice (usually below). FIRN ICE 41 42 Where are the firn line, equilibrium line, snow line relative to each other?

Sensitivities Claridenfirn, Switzerland, 1916 negative mass balance firn line retreats slower balanced year: Lines are the same only when glacier

11 FIRN Wetted snow that has survived one summer without being transformed to ice FIRN LINE FIRN LINE can be seen on radar profiles Snow surface Mass balance The set of points on the surface of a glacier delineating the firn area and, at the end of the mass-balance year, separating firn (usually above) from glacier ice (usually below). FIRN ICE Where are the firn line, equilibrium line, snow line relative to each other? firn<snow=el if no superimposed ice firn=snow=el if no superimposed ice Vatnajoekull (Iceland) firn=snow=el if no superimposed ice PART IV Sensitivities Claridenfirn, Switzerland, 1916 negative mass balance firn line retreats slower balanced year: Lines are the same only when glacier is in equilibrium (i.e. balance=0 over many years and firn line = long-term EL) positive massbalance, remaining snow becomes firn --> all lines are the same

12 Sensitivities to climate change The change in mass balance due to a change in a climatic variable such as air temperature or precipitation. Sensitivities to temperature and precipitation are often expressed as changes in response to a 1 K warming or a 10% precipitation increase, Static sensitivities assume constant glacier size and geometry and refer only to the change in mean specific mass balance dynamic sensitivities consider the volume and geometry changes following climate change and are thus more realistic Sensitivities vary among regions (e.g. maritime climates more sensitive) Bn = mean specific annual mass balance x = perturbation of the climate, i.e. temperature or precipitation A = glacier area, V=glacier volume, T= temperature change during period t-t0 45 Static mass balance sensitivities using energy balance (EB) or temperature-index (TI) melt models Glaciers Method Static mass balance sensitivity T +1 K (m a -1 ) Static mass balance sensitivity P +10 % (m a -1 ) Reference 3 Norwegian glaciers EB to Oerlemans (1992) 12 glaciers EB to Oerlemans and Fortuin (1992) 12 glaciers EB (average) Oerlemans (1993) 3 Norwegian glaciers TI to to Laumann and Reeh (1993) 2 Svalbard glaciers EB (average) Fleming et al. (1997) 2 Icelandic glaciers TI -0.6 to -0.9 Jóhannesson (1997) 12 glaciers TI, EB -0.4 to Oerlemans et al. (1998) 37 glaciers TI -0.1 to -1.3 Braithwaite and Zhang (1999) 5 Swiss glaciers TI to Braithwaite and Zhang (2000) 6 Scandinavian glaciers TI to to Nesje et al. (2000) 61 glaciers TI to to Braithwaite et al. (2002) 9 Icelandic glaciers EB to to de Ruyter de Wildt et al. (2003) 17 glaciers TI -0.2 to -1.5 Schneeberger et al. (2003) 42 Arctic glaciers TI to to de Woul and Hock (2005) 12 Scandinavian glaciers TI to to Rasmussen and Conway (in press) 46 What do mass balance sensitivities depend on? Affected by Glacier geometry Climate Annual mass balance sensitivity [m a -1 ] to a +1 K warming Regions with high sensitivities due to change in rain/snow fraction has a larger effect where precip is higher longer ablation season has larger effect on glaciers that extend down to low-lying warmer areas greater reduction in precip in maritime regions for a given percentage change in precip Hock et al., 2009, GRL 47 48

Mass balance sensitivities Global mean static mass balance -0.39 m a -1 K -1 (Oerlemans, 1993) -0.37 m a -1 K -1 (Dyurgerov and Meier, 2000) -0.

, 2009) Future volume changes using mass balance sensitivities S T = Mass balance sensitivity to +1 K warming S P = Mass balance sensitivity to 1% precipitation

with time 49 50 Seasonal sensitivity characteristic Seasonal mass balance sensitivities applies temperature and precipitation perturbations employed individually for

13 Mass balance sensitivities Global mean static mass balance m a -1 K -1 (Oerlemans, 1993) m a -1 K -1 (Dyurgerov and Meier, 2000) m a -1 K -1 (Hock et al., 2009) Future volume changes using mass balance sensitivities S T = Mass balance sensitivity to +1 K warming S P = Mass balance sensitivity to 1% precipitation increase ΔT = predicted temperature increase ΔP = precipitation increase (%) Assumptions: Assumption that glacier initially are in steady-state Constant sensitivities with time Seasonal sensitivity characteristic Seasonal mass balance sensitivities applies temperature and precipitation perturbations employed individually for each month while leaving the data for the remaining months unchanged. Sensitivity varies with season applies temperature and precipitation perturbations employed individually for each month while leaving the data for the remaining months unchanged. SSC (Oerlemans & Reichert, 2000): Monthly perturbations in precipitation or temperature 51 52

Claridenfirn, Switzerland, 1916 PART IV What is Glacier runoff?

Short-term time scale Response to warming Period of negative mass

runoff projections 2006-2100 53 54 What is glacier runoff? 1.

zero glacier in balance has no effect on annual runoff (but

) Runoff from glacier net mass loss Q = M - R + P relevant for

) Runoff only from bare ice area Q = Mice Bliss et al.

14 Claridenfirn, Switzerland, 1916 PART IV What is Glacier runoff? How does runoff change modify runoff as it becomes warmer? Short-term time scale Response to warming Period of negative mass balances Balanced mass budget Long-term time scale 1914 Glacier runoff projections What is glacier runoff? 1.) All runoff from glacierized area Q = M - R - discharge a gauging station would measure happens always, i.e. also in year where annual net balance is zero glacier in balance has no effect on annual runoff (but seasonal effects) relevant for hydrologists 2.) Runoff from glacier net mass loss Q = M - R + P relevant for sea-level extra water from long-term glacier storage 3.) Runoff only from bare ice area Q = Mice Bliss et al., JGR, 2014 Radic V. and R.Hock, Glaciers in the Earth s hydrological cycle. Assessments of glacier mass and runoff changes on global and regional scales. Survey of Geophysics 35,

Sea-level equivalent (mm yr- 1 ) Claridenfirn, Switzerland,

Sea-Level Equivalent (SLE) ~66 m 58.3 m Antarctica 7.

5 m mountain glaciers Mountain glaciers and ice caps ~195,000

Greenland (89,700 km 2 ) and Antarctica (133,200 km 2 ) 1914

Truessel 57 58 Ice volume Mountain glaciers (1%) Sea-level

(IPCC, 2007) Greenland 11% Antarctica 88% Thermal expansion

glacier contribution roughly equivalent to ice sheet mass loss

2006, GRL; IPCC 2007 2010 1960 2000 based on 3 global

15 Sea-level equivalent (mm yr- 1 ) Claridenfirn, Switzerland, 1916 PART IV Global mass balances Global glacier volume Sea-Level Equivalent (SLE) ~66 m 58.3 m Antarctica 7.4 m Greenland 0.5 m mountain glaciers Mountain glaciers and ice caps ~195,000 glaciers 705 km 2 including glaciers in the periphery of Greenland (89,700 km 2 ) and Antarctica (133,200 km 2 ) 1914 Yakutat Glacier, Alaska 2011; photo: B. Truessel Ice volume Mountain glaciers (1%) Sea-level contribution , IPCC 2013 Global glacier mass loss (IPCC, 2007) Greenland 11% Antarctica 88% Thermal expansion Glaciers Greenland Antarctica Land water storage : glacier contribution roughly equivalent to ice sheet mass loss : SLE= 0.77±0.22 mm/yr 2006 Kaser et al. 2006, GRL; IPCC based on 3 global estimates (Cogley, 2005; Dyurgerov & Meier, 2005; Ohmura, 2004) based on spatial extrapolation of measured mass balances incomplete glacier inventory : mm yr -1 (Cogley 2009) 59 60

Journal of Glaciology, Vol. 60, No. 221, 2014 doi: 10.

Tad PFEFFER, 1 Anthony A. ARENDT, 2 Andrew BLISS, 2 Tobias BOLCH, 3,4 J. Graham COGLEY, 5 Alex S. GARDNER, 6 Jon-Ove HAGEN, 7 Regine HOCK, 2,8 Georg KASER, 9 Christian KIENHOLZ, 2 Evan S.

SHARP, 14 THE RANDOLPH CONSORTIUM 15 1 Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO, USA 2 Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK, USA 3

Peterborough, Ontario, Canada E-mail: gcogley@trentu.

Sweden 9 Institute of Meteorology and Geophysics, University of Innsbruck, Innsbruck, Austria 10 Scott Polar Research Institute, University of Cambridge, Cambridge, UK 11 Institute of Geophysics and

Vancouver, British Columbia, Canada 13 National Snow and Ice Data Center, University of Colorado, Boulder, CO, USA 14 Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton,

The Randolph Glacier Inventory (RGI) is a globally complete collection of digital outlines of glaciers, excluding the ice sheets, developed to meet the needs of the Fifth Assessment of the

16 Journal of Glaciology, Vol. 60, No. 221, 2014 doi: /2014JoG13J inventoried glacierized area (WGI) - NOT inventoried glacierized area before 2012 The Randolph Glacier Inventory: a globally complete inventory of glaciers W. Tad PFEFFER, 1 Anthony A. ARENDT, 2 Andrew BLISS, 2 Tobias BOLCH, 3,4 J. Graham COGLEY, 5 Alex S. GARDNER, 6 Jon-Ove HAGEN, 7 Regine HOCK, 2,8 Georg KASER, 9 Christian KIENHOLZ, 2 Evan S. MILES, 10 Geir MOHOLDT, 11 Nico MÖLG, 3 Frank PAUL, 3 Valentina RADIĆ, 12 Philipp RASTNER, 3 Bruce H. RAUP, 13 Justin RICH, 2 Martin J. SHARP, 14 THE RANDOLPH CONSORTIUM 15 1 Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO, USA 2 Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK, USA 3 Department of Geography, University of Zürich, Zürich, Switzerland 4 Institute for Cartography, Technische Universität Dresden, Dresden, Germany 5 Department of Geography, Trent University, Peterborough, Ontario, Canada gcogley@trentu.ca 6 Graduate School of Geography, Clark University, Worcester, MA, USA 7 Department of Geosciences, University of Oslo, Oslo, Norway 8 Department of Earth Sciences, Uppsala University, Uppsala, Sweden 9 Institute of Meteorology and Geophysics, University of Innsbruck, Innsbruck, Austria 10 Scott Polar Research Institute, University of Cambridge, Cambridge, UK 11 Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA, USA 12 Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, British Columbia, Canada 13 National Snow and Ice Data Center, University of Colorado, Boulder, CO, USA 14 Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta, Canada 15 A complete list of Consortium authors is in the Appendix ABSTRACT. The Randolph Glacier Inventory (RGI) is a globally complete collection of digital outlines of glaciers, excluding the ice sheets, developed to meet the needs of the Fifth Assessment of the Intergovernmental Panel on Climate Change for estimates of past and future mass balance. The RGI was created with limited resources in a short period. Priority was given to completeness of coverage, but a limited, uniform set of attributes is attached to each of the glaciers in its latest version, 3.2. Satellite imagery from provided most of the outlines. Their total extent is estimated as km 2. The uncertainty, about 5%, is derived from careful single-glacier and basin-scale uncertainty estimates and comparisons with inventories that were not sources for the RGI. The main contributors to uncertainty are probably misinterpretation of seasonal snow cover and debris cover. These errors appear not to be normally distributed, and quantifying them reliably is an unsolved problem. Combined with digital elevation models, the RGI glacier outlines yield hypsometries that can be combined with atmospheric data or model outputs for analysis of the impacts of climatic change on glaciers. The RGI has already proved its value in the generation of significantly improved aggregate estimates of glacier mass changes and total volume, and thus actual and potential contributions to sea-level rise. KEYWORDS: Antarctic glaciology, Arctic glaciology, glacier delineation, glacier mapping, remote sensing, tropical glaciology Yakutat Glacier 61 IACS Activities Resources About IUGG WG co-chairs : Graham Cogley, Trent University, Peterborough, Canada Regine Hock, University of Alaska Fairbanks, USA WG members : IACS Working group Division on Glaciers and Ice Sheets Randolph Glacier Inventory and infrastructure for glacier monitoring ( ) Etienne Berthier, CNRS-OMP-LEGOS, Toulouse, France Andrew Bliss, University of Alaska Fairbanks, USA Tobias Bolch, University of Zürich, Switzerland and Technische Universität Dresden, Germany Koji Fujita, University of Nagoya, Japan Alex Gardner, Clark University, USA Matthias Huss, University of Fribourg and ETH Zürich, Switzerland Georg Kaser, University of Innsbruck, Austria Christian Kienholz, University of Alaska Fairbanks, USA Anil Kulkarni, Indian Institute of Science, Bangalore, India Shiyin Liu, Cold and Arid Regions Environmental & Engineering Research Institute, Lanzhou, China Christopher Nuth, University of Oslo, Norway 62 Goal of the Working Group The Randolph Glacier Inventory (RGI) is a recentlypublished, globally complete collection of digital outlines of glaciers, excluding the ice sheets. The Working Group aims to maintain and develop the RGI as a resource for global/regional-scale mass-balance assessments and projections and work towards merging the RGI into the Global Land Ice Measure-ments from Space (GLIMS) database. Scope: Background Objectives Research Institute, Lanzhou, China Deliverables and milestones Christopher Nuth, University of Oslo, Norway Ben Marzeion, University of Innsbruck, Austria Takayuki Nuimura, University of Nagoya, Japan Frank Paul, University of Zürich, Switzerland Valentina Radić, University of British Columbia, Canada Bruce Raup, National Snow and Ice Data Center, Boulder, USA Akiko Sakai, University of Nagoya, Japan Donghui Shangguan, Cold and Arid Regions Environmental & Engineering Research Institute, Lanzhou, China Arun Shrestha, International Yakutat Centre Glacier, for Integratred Alaska 2011; Mountain photo: B. Truessel Development, Kathmandu, Nepal Mass changes (IPCC 2013) Approach: combine best available estimates for each region with new analyses based on ICESat GRACE (Gravity Recovery and Climate Experiment)! Glaciological W US/Canada, Scandinavia, North Asia, central Europe, Caucasus, low latitudes, New Zealand GRACE Alaska ICESat Greenland, Antarctica GRACE+ICESat Arctic Canada, Svalbard, Russian Arctic, High Mountain Asia Launched in March of 2002, GRACE consists of twin satellites in the same orbit 220 km apart with the purpose to measure Earth s gravity variations Use microwave ranging system to measure change in distance between each other If leading satellite approaches a mass anomaly it will pull away from the other Measures directly change in mass Gardner, A. S., Moholdt, G., Cogley, J. G., Wouters, B., Arendt, A. A., Wahr, J., Berthier, E., Hock, R., Pfeffer, W. T., Kaser, G., Ligtenberg, S. R. M., Bolch, T., Sharp, M. J., Hagen, J. O., van den Broeke, M. R., and Paul, F. 2013: A Reconciled Estimate of Glacier Contributions to Sea Level Rise: 2003 to 2009, Science See summer school lecture 2014 on GRACE by Tyler Sutterley 64 Source:

Mass changes 2003-2009 Potential sea-level rise: Main regions Mass change Area blue = tidewater glaciers Gardner et al. 2013, Science Mass loss = 259 ± 28 Gt yr -1, 0.71 ± 0.08 mm SLE yr -1, -0.

17 Mass changes Potential sea-level rise: Main regions Mass change Area blue = tidewater glaciers Gardner et al. 2013, Science Mass loss = 259 ± 28 Gt yr -1, 0.71 ± 0.08 mm SLE yr -1, m yr -1 --> 29% of observed global sea-level rise (2.5 mm yr -1 ) Roughly equivalent to ice sheet mass loss (289 ± 49 Gt yr -1 ) Mass Largest contributors: Arctic Canada, Alaska, Greenland periphery, Southern Andes Potential sea-level rise: Main regions 1 ice sheet 4 5 Relevant for water resources: Main regions ice sheet 3 2 Potential of mountain glaciers 2 Potential of mountain glaciers ice sheet ice sheet ice sheet mountain glaciers Radic et al., ~66 m SLE 58.3 m Antarctica 7.4 m Greenland 0.5 m mountain glaciers ice sheet mountain glaciers Radic et al.,

Volume projections 2015-2100: Global (excluding Antarctic periphery) Emission scenario: RCP2.6 RCP4.5 RCP8.

Huss&Hock Bliss/Radic et al. Slangen et al.

18 Volume projections : Global (excluding Antarctic periphery) Emission scenario: RCP2.6 RCP4.5 RCP runs 64 runs 80 runs -15% -18% thick lines= multi-model means -29% -38% Roughly 8-22 cm of sea-level rise by 2100 from glaciers outside the ice sheets -26% -55% Marzeion et al Giesen&Oerlemans Huss&Hock Bliss/Radic et al. Slangen et al. Summary Specific mass balance: mass per area surface mass balance: strictly speaking only balance at the surface -> climatic balance if internal accumulation included annual balance instead of previous term net balance Accumulation is not identical to net accumulation Runoff is not identical to melt or meltwater runoff Frontal ablation includes calving flux and submarine melting Reporting of time systems and glacier area (areaelevation distribution) is crucial Conventional balance (area, elevation updated) reference surface mass balance (kept constant) Take-home message Reporting mass balance: always report domain to which balance refers (and area) time period a balance refers to if annual balance is reported report the dates and/or the time system (--> essential to compare to model results) report which mass balance component is measured/ modeled; use proper terminology 71

Regional and global projections of twenty-first century glacier mass changes in response to climate scenarios from global climate models

Clim Dyn DOI 10.1007/s00382-013-1719-7 Regional and global projections of twenty-first century glacier mass changes in response to climate scenarios from global climate models Valentina Radić Andrew Bliss