U.S. Continental Scientific Drilling and Coring Science Plan Paleorecords community - Highlights

Transcription

1 U.S. Continental Scientific Drilling and Coring Science Plan Paleorecords community - Highlights

2 Earth systems across time Sediment records in mud and rock on the Earth s continents offer an unparalleled view of the history of the places we care about: where people live, where plants and animals have evolved, and where we will feel the impacts of future environmental changes. Continental scientific drilling and coring are the best and often the only ways to access these archives. The scientists who use continental core samples to understand the past come from many different disciplines: Earth science, ecology, anthropology, geography, and more. They may collect cores in small teams, using hand-operated equipment or they may work in large, international collaborations with heavy equipment to drill on land or from the surfaces of lakes. All of these researchers have common goals, however: to place our current and future Earth in the context of conditions during the past thousands to millions of years. There are many intersections among the questions that they ask, reflecting the interconnectedness of Earth systems, and the human systems that depend upon them. With contributions from 120 members of the community to date, the U.S. Continental Scientific Drilling and Coring Community Science Plan provides an invitation to answer some of the most exciting and important scientific questions about the Earth s long history of changing climate, water supply, temperatures, life and ecosystems, human-environment interactions, and natural hazards. This summary highlights these questions and their scientific context, as well as the sites and methods proposed by the community to address them. The entire Paleorecords Draft Science Plan can be accessed at CSDCO.org. To provide input, or for questions related to the science planning process, workshops, etc., please contact CSDCO@umn.edu. The central role of geochronology The scientific questions investigated by the continental drilling community rely heavily on robust, highquality chronologies. The science of geochronology investigates the time dimension of Earth s history, and seeks to answer fundamental questions of process rates, periodicity, spatial patterns, and sequence and synchroneity, by advancing the precision, range, and application of existing chronological tools and by developing new tools with the power to transform our understanding of Earth s history and processes. Dates and rates are overarching concerns, and geochronology is arguably essential for every paleorecord study no matter which proxies are chosen to investigate.

3 Water supply and climate change How does the water cycle vary in changing climates? How do surface and subsurface hydrology respond to climate change? How did past tectonics, vegetation, and sea levels influence precipitation patterns and surface hydrology? Surface and groundwater movement and storage govern the availability of water for use by human societies and ecosystems. Existing paleohydrologic records suggest that thresholds may exist not only in climate, but in regional hydrologic systems. For instance, the western US may have oscillated between a system in which freshwater is stored primarily at the surface, in the form of large lakes, to a system in which significant quantities exist only in the subsurface. Such transitions may involve highly heterogeneous changes in precipitation and hydrology within regions, challenging our modeling capabilities. Our current understanding of precipitation changes in the past has advanced tremendously, particularly for changes that have occurred since the last ice age. However, the climate of the last ~20,000 years presents an extremely limited range of climate variation, and does not speak to hydroclimatic changes occurring in response to climates that were warmer than the present. Continental scientific drilling presents the opportunity to ask relevant questions about the water cycle in past warm periods at high resolution, in numerous climatically-sensitive sites. The community must move from relatively simplistic reconstructions of wetter vs. drier to more quantitative reconstructions of key elements of the water cycle. Quantifying hydrologic mechanisms yields ancillary benefits: Basin-specific hydrologic studies are often considered part of site characterization, especially for studies of the recent past (e.g., Holocene), but also have clear practical benefits for local communities and stakeholders in that they improve understanding of societally relevant aspects of local and regional hydrology.

4 Temperatures in the past and future What are the spatial and temporal patterns of temperature change over the Earth s continents in the geologic past? Which key time intervals can better inform climate models of future conditions? How did atmospheric CO2 forcings and feedbacks regulate regional and global temperature prior to the Quaternary? Our world is warming at a rate that is unprecedented in the instrumental record, causing rises in sea level that already impact coastal cities and transportation infrastructure. At the same time, changes in Earth s temperature are altering equator-to-pole gradients that are driving changes in regional to hemispheric weather patterns. The frequency of temperature extremes has risen over the past decade with long lasting heat waves having deadly impacts. High resolution sediment records from continental basins are among the best archives of the history of global climate change at the spatial and temporal scales required to be relevant to current and future societies. The ability to provide reliable and relevant information about past changes in temperature (and associated hydrologic and biologic impacts) requires a strategically distributed network of high resolution sites. Specific types of sites in space and time are critical for understanding regional temperature variability, the mechanisms driving global climate change, and for improving climate models. There is a need for additional temperature reconstructions from Arctic and Antarctic sites as well as for PaleoceneEocene sites with better chronology to examine early Cenozoic greenhouse climates. There is a need for the development of mid-latitude continental records, a current gap in our understanding of climate dynamics.

5 Life and ecosystems over time What are the patterns, rates, and drivers of speciation and extinction through time? How have disturbances driven ecosystems, and what are the implications for future ecosystem stability? How have feedbacks such as in carbon and nutrient cycles, weathering and transport affected ecosystems in the past? What ancient environments offer the best analogs for past life on Mars? Continental drilling and coring enable the study of life during conditions that do not presently exist on Earth. The continuous and long-term records from drill cores capture feedbacks among drivers and responses in biotic systems. In turn, lessons from the past inform our understanding of environmental conditions that we may encounter in the future. A diverse range of environments, ecosystems, and organisms can be assessed: potentially all taxonomic groups in both terrestrial and aquatic systems. Questions addressed by modern studies of ecosystem processes, evolution, and biodiversity can be complemented by the longer timescales of paleobiology. Because of this biological climate sensitivity, paleobiological research does more than benefit from associated studies of hydroclimate and temperature: it can also contribute to those studies. Similarly, analysis of events billions of years in the past, such as global oxidation events and colonization of the continents by organisms, provide insight into early life-earth dynamics. Since the emergence of life on Earth approximately 3.6 billion years ago, the biosphere and geosphere have been tightly linked by microbes. Having developed a wide variety of metabolic strategies, they contribute critically to the flux of elements into and out of biomass. As life has proliferated on Earth it has diverted a number of bio-necessary elements particularly carbon, but also N, O, P and a number of metals from the inorganic geosphere to the biosphere. Over geologic time this has affected the evolution of the atmosphere, as well as the proliferation and distribution of minerals.

6 The human dimension When in Earth s history do the first human impacts appear? Did climate change drive human evolution? How did prehstoric human societies shape ecosystems that we often view as pristine in North America and elsewhere? What do paleorecords tell us about periodicity, clustering, and randomness of natural hazards? Humans are unquestionably playing a major role in shaping modern ecosystems and environments, but deep time perspectives are essential to contextualize the extent of human impacts, and somewhat paradoxically, to understand the role that environmental change has played in shaping contemporary human societies. Human societies are inherently susceptible to changes in climate. While technology can mitigate many of these risks, it also has the potential to make societies even more vulnerable to large and/or rapid changes in climate. Future research should pair high-quality, highresolution, multi-proxy paleo-records with detailed archaeological histories to assess the ability of societies to respond to climate change through time and through different stages of technological development. While many studies have focused on responses of prehistoric societies to climatic change, it remains unclear if these past events can serve as true analogues for modern or future societal responses to climate change. Historic records and the human timescale of observation are short relative to the recurrence intervals of natural hazards. Lakes record in their sediment stratigraphy the histories of earthquakes, volcanic eruptions, tsunamis, droughts, and storm events, and potentially their environmental impacts as well, over periods of hundreds to millions of years. Therefore, analysis of long-term paleo-archives is a uniquely important element in assessing future hazards, evaluating the risk to nearby populations, and to prepare for and mitigate the next event. More fundamentally, stratigraphic records provide data necessary for understanding the underlying processes that control the recurrence and severity of natural hazards.

7 Implementation Improved support for project development A dynamic 21st century tool kit for drilling/ coring and analysis Optimized workflows and integrated facilities and data management operations. to establish local contacts and logistical requirements represents critical groundwork for any core-based science, but viable mechanisms are needed to fund these essential surveys and activities. Centralized funding, contracting, and management for drilling operations would yield major benefits to projects at all levels. Changes to funding mechanisms for drilling projects represents a major community goal. The cost of drilling relative to the annual budgets of disciplinary programs within funding agencies currently limits projects of certain scientific focus or size. Many projects currently in the development seek to recover drill cores substantially longer than those from past projects, to address the societally critical goal of understanding warm climates of the past. It is imperative that the community can access the financial resources required to utilize and develop drilling technologies that improve depth capacity. In addition, site characterization, to understand process controls on sediment deposition, establish drilling locations for optimal record quality, to evaluate drilling risk and safety considerations, and Expansion of the availability of new types of nondestructive core analysis tools is actively sought by researchers. CSDCO should further develop its role in development of these cutting-edge technologies, and in the standardization of data outputs. Techniques promoting core and subsample integrity must be developed in support of new advances in analytical techniques and core science priorities. Data quality assurance, methodological transparency and reporting consistency are particular challenges to the paleorecords community, within which practitioners employ many different analytical techniques, some emerging and others more mature, directed toward shared interpretations. Greater integration of visualization and core description tools, and data flows to community data resources, are highly prioritized by the community. Databases and related tools are important to the community as archives, and to enable research on largescale patterns and relationships and model testing.

8 , , , Ho Neogene Pleistocene 104 Age (yr) , 21, , 4, 32 5, 20 6, 24, 25, , 15, 19, 31, 39 Projects with unspecified locations: 44, , 18 22, , 33, Paleogene Mesozoic Proterozoic Paleozoic Age (yr) Sites proposed by members of the continental scientific drilling (CSD) community by location (above) and geologic time interval (left). Numbers refer to abstracts in Appendix 1 of the full Science Plan. During workshops in the CSD community will work to prioritize among these sites using criteria developed in earlier workshops. 1, CSDCO/LacCore acknowledges the hard work and contributions of over 120 members of the continental scientific drilling and coring community to the Paleorecords Draft Science Plan. The entire document is available for download at CSDCO.org. We urge other community members to provide input by contacting CSDCO@umn.edu Graphic by Sarah Horns CSDCO L A C C O R E LacCore.org CSDCO and LacCore are supported by NSF awards and , respectively. 109 National Lacustrine Core Facility v