Climate Research and Development

Project Archive

Previous research efforts from the Climate Research and Development Program.

Alaskan Quaternary Climate Change — Tom Ager
   This project involves reconstruction of the late Pleistocene and Holocene history of environmental change in Alaska, focusing upon the past 50,000 years. High latitude ecosystems are highly sensitive to climatic change. Understanding the history of environmental responses to past climate changes provides a basis for forecasting future responses to a variety of possible climatic scenarios. Information derived from this study has applications to ecology, paleoecology, paleoclimatology, archeology, vertebrate paleontology, and other fields. Understanding ecosystem history is also crucial for proper management of national forests, national and state parks, and wildlife refuges.

Assessing Population Projections for Beaufort Sea Polar Bears — Todd Attwood
   The polar bear is recognized worldwide as a vulnerable species due to global warming induced loss of its required sea ice habitats. USGS science played a central role in informing the 2008 decision by the Department of the Interior to list the polar bear as threatened under the Endangered Species Act. This science was founded in understanding gained from long-term studies of the southern Beaufort Sea (SB) population, one of 19 worldwide, and one of only two populations with long-term data. In these studies, USGS documented a negative relationship between length of the open water season over the continental shelf and population growth rate. Applying future sea ice conditions, as projected from climate models developed by the Intergovernmental Panel on Climate Change, to the relationship between sea ice availability and population growth rate allowed us to project a future trajectory of the population. In this current project supported by CLU R&D, we are monitoring the survival and habitat use of the SB population to determine (i) whether available habitat changes as projected and (ii) how observed changes influence population dynamics. Information about how polar bears in this population respond to sea ice loss will inform projections for the worldwide population.

Assessment of Potential Hydrologic Effects of Sea Level Rise — John Masterson
   The purpose of this project is to analyze the shallow, permeable, groundwater flow system beneath Assateague Island National Seashore as part of a larger, multi-disciplinary effort designed to assess the potential impacts of sea-level rise and provide tools for coastal management decision making. The initial phase of this effort was to install wells to record water levels. The wells were also used for geophysical measurements to determine salinity of the groundwater. The next phase focused primarily on developing a calibrated three-dimensional ground-water flow model capable of simulating both the fresh and saltwater flow systems to examine the response of groundwater levels and the position of the freshwater/saltwater interface that occur as the elevation of the sea surface increases.
   Results from this analysis suggest that simulated changes in sea level of less than 60 cm above present levels will result in substantial changes to the groundwater system including an increase in water-table altitude and increased potential for saltwater intrusion. The results from this hydrogeologic analysis will be integrated with related predictions of island erosion, overwash and inundation and marsh resilience developed by other parts of the larger project using a Bayesian decision network. This Bayesian network integrates a wide range of geologic, biologic, and hydrologic information on coastal systems and the related uncertainties in physical and process characterizations. The groundwater assessment and modeling fits into the larger constellation of processes to allow support decision making and evaluate specific management questions about alternatives for adapting to SLR, as well as to identify research needed to improve predictive skill.

Why is this research important?
   Assateague Island, spanning the Maryland-Virginia border has been identified as one of the national seashores facing significant risk from the effects of global climate change. This vulnerability is due to the inherently dynamic and unstable nature of barrier islands, the natural resources present on the island, and to its location in a region experiencing some of the highest rates of relative sea level rise along the east coast of the United States. These changes will impact use of the island by both humans and fauna; specifically, the island serves as an important breeding ground and habitat for endangered species such as the Piping Plover. The impact of climate change and sea-level rise in particular, is expected to include changes in erosion rates, island morphology, marsh health, and groundwater processes.

Atlantic Estuaries: Chesapeake Bay — Deb Willard
   Eastern U.S. estuaries have common environmental problems: degraded water quality, loss of wetlands and riparian zones, sea-level rise, sedimentation, coastal erosion, declining fish and wildlife populations, loss of sub-aquatic vegetation (SAV) and increased algal blooms. Population growth, urban sprawl, intensified agriculture, and climate change exacerbate these. Mitigation of estuarine issues requires understanding of ecological, physical, and chemical changes due to climate variability and anthropogenic factors, the influence of regional geological framework, and impacts of land-use changes in watersheds and coastal zones. This project provides a scientific basis for resource managers and other policy-makers to address these issues. The initial work was in Chesapeake Bay, and eventually it will shift to other mid-Atlantic estuaries (possibly including, but not limited to, Albemarle and Pamlico Sounds, Chicoteague, and Delaware Bay) and apply techniques developed in Chesapeake Bay to issues in those estuaries.

Climate Change, Land Use, and Environmental Sensitivity — Robert S. Thompson
   This project seeks to provide long-term perspectives on natural variability and on environmental impacts of past climatic changes on arid and semiarid Federal lands in the western United States (with a particular emphasis on the Holocene of the Upper Colorado River Basin). Our research addresses the nature, timing, and environmental effects of Late Quaternary climatic changes across this physiologically complex region, which encompasses geographic and elevational gradients in temperature, moisture, and the seasonality of precipitation. Consequently, we aim to reconstruct climatic and environmental variability and change for the past 25,000 years in four dimensions (time, latitude, longitude, and elevation) across a broad spatial coverage that captures the primary climatic gradients of this region.
   The scientific work of the CLUES2 project includes characterizing the modern relations between climatic parameters and plant distributions; studying past changes in plant distributions, lake environments, and other environmental indicators; developing methods to obtain quantitative estimates of past climatic conditions (with associated uncertainty values); and, comparing our reconstructions with numerical model simulations of past climatic and environmental conditions.

Why is this research important?
   Studies of the past reveal how much and how quickly climate can change, even without the potential effects of human actions. In the western United States, past climatic changes were complex, differed in degree across elevation, and included changes in mean conditions, variability, and seasonality. Ecosystem responses were also complex, with different species having different thresholds that caused either die offs in the previously acceptable ranges and/or opportunities for dispersal to new habitats. As a consequence, biotic communities were ephemeral and undergoing constant change. It should be expected that future climatic changes will also be complex, as will the environmental responses to these changes.
   The comparison of paleoclimatic and paleoenvironmental reconstructions with model simulations for key past time periods provides information and insights that may be important in considering potential future changes. This comparison provides a basis for evaluating how well models can simulate conditions different from those of today. In addition, model simulations may indicate the climatic circulation patterns responsible for geographic and elevational patterns observed in the paleo reconstructions.

Climate Impacts on Semi-Arid Land Wetlands and Birds — Susan M. Haig
   We are developing methods to effectively assess landscape-level impacts of climate change on wetlands and wetland-dependent species in semi-arid areas of North America's Great Basin. The terrestrial and aquatic animals that depend on Great Basin wetlands are likely to experience shifts in range, phenology, and population structure, including loss of landscape-level connections among necessary fresh (nesting) and alkali (feeding) water habitats required for different life stages. Using remote sensing and on-the-ground research (weather, water quality, hydrology), we are assessing the relationship between climate, water quality, and water volume. We are also measuring the genetic connectivity of the aquatic invertebrates that serve as key prey species to the millions of migratory waterbirds that depend on these wetlands. Thus, allowing us to understand how different animals are genetically connected across the landscape to predict where these prey items may persist under future climate regimes. The end result is that we will be able to model how wetland habitat quality and species connectivity will change in the coming decades. This approach can be used around the world to help researchers, managers, and policy makers understand population- and community-level climate impacts for timely conservation planning and adaptive management.

Why is this research important?
   Wetlands are inherently vulnerable to shifts in climate, and the species that depend on them are also likely to experience significant shifts. We aim to understand how climate change will alter the inter-related factors of hydrology and species connectivity of wetlands. This project addresses the priority theme Impacts of Climate and Land-Use Change on Terrestrial and Marine Systems.

Documenting Post-Little Ice Age Glacier Behavior and Landscape Evolution in Alaskan National Parks and National Forests — Bruce Molnia
   Glacier's are the largest reservoir of freshwater on Earth and the single most significant source of meltwater entering the global ocean. In the temperate glacier world, the primary source of meltwater entering the global ocean is the glacierized region of Alaska and adjacent Canada. The majority of temperate glaciers that are contributing to rising sea levels are located in Glacier Bay National Park and Preserve, Wrangell-St Elias National Park, Denali National Park, Kenai Fjords National Park, Katmai National Park, Lake Clark National Park & Preserve, Gates Of The Arctic National Park & Preserve, Aniakchak National Monument & Preserve, Katmai National Park & Preserve, Klondike Gold Rush National Historical Park, Tongass National Forest, and Chugach National Forest. A large volume of water remains in Alaskan glaciers. Therefore, the response of existing glaciers to changing climate is a significant factor in future meltwater production. A future sea level rise of even a few centimeters can have a devastating impact on Earth's low elevation coastal areas. Consequently, determining Alaska's potential role in future sea level change is of critical importance.

Effects of Climate Change on Montane Riparian Ecosystems — Thomas E. Martin
   This research continues and extends long-term (25 years) study of climate effects on an ecosystem classified as high priority and vulnerable: a montane riparian system in the arid southwest. We are examining the causal mechanisms (both physiological and ecological) underlying demographic sensitivities to climate variation that result in changes in ecosystem structure (species composition) and function (trophic interactions). The research includes estimation of long-term population trajectories and demographic sensitivity of a full array of vegetation, bird, and mammal species and their trophic interactions to climate variation in order to project future responses and possible management alternatives. We are testing the trickle-down effects of long-term changes in snow levels on elk herbivory and consequences for plant densities and the resulting myriad effects on the animals that depend on these plants. We also are examining how changes in plants and summer temperatures affect avian embryo physiology and predation and thereby influence demography, parental behavior, and offspring quality.

Why is this research important?
   Study of multiple trophic groups and their interactions are rare, but urgently needed to understand causal mechanisms of ecosystem change in response to climate. We are examining climate effects on trophic interactions (herbivory, predation) between large herbivores, plants, small mammals and birds - the only such study in the world examining this range of trophic interactions and over a long enough time-frame to see climate influences. In addition, we are examining the causal mechanisms and hierarchical scaling underlying change in ecosystem structure (species composition) and function (trophic interactions) in response to climate variation. Finally, we are examining physiological sensitivities of birds and their offspring to climate and the resulting potential consequences from warming.

FISCHS — Catherine A. Langtimm
   The objective of this project is to integrate biological and hydrological models to develop management tools to deal with the projected ecological consequences of rising sea level in coastal south Florida. To develop a realistic suite of predictive tools, we are (1) Mapping the position of the mangrove-marsh ecotone at selected locations for six time periods, determining rates of change and relating those rates to rates of sea-level rise; (2) Developing new mechanistic models of coastal vegetation change and determine thresholds and tipping points for change; (3) Incorporating episodic disturbance from hurricanes to identify its impact on hydrology and vegetation; (4) Enhancing a coupled surface-water/ground-water hydrologic model to reliably hind-cast multi-decadal observed sea level rise, hurricane effects, and vegetation change; (5) Developing future-casting capability under projected climate change, SLR, and restoration scenarios. The insight on hydrologic, ecological, and topographic changes obtained from the Hindcast experimentation is used to extrapolate changes in the future-cast simulations; and (6) Using the hydrologic models to simulate variables for spatially-explicit population and habitat suitability index models for application to management problems.

Lake/Catchment Systems (LACS) — Joe Rosenbaum
   The USGS Bear Lake Project started in 1998 with the goal of creating records of past climate change for the Bear Lake region, including changes in precipitation (rain and snow) patterns during the last 10,000 years. As part of the project, we're determining how the size of Bear Lake has varied in the past, to assess the possibility of future flooding and drought. Our study includes the upper Bear River watershed. The Bear River is the largest river in the Great Basin and the source of the majority of water flowing into the Great Salt Lake. In this region, wet periods may produce flooding along the course of the Bear River and around Great Salt Lake, while dry periods, or droughts, may affect water availability for agricultural, industrial and residential use.

Last Interglacial Timing & Environment (LITE) — Dan Muhs
   The last interglacial period has been cited as a possible analog for a future climate under an increased-CO2 greenhouse warming. Previous studies have shown that during the last interglacial CO2 concentrations in the atmosphere were relatively high temperatures may have been higher than the present, and sea level may have been ~6 m higher. The ultimate goals of the LITE project are to (1) develop an accurate estimate of the duration of the last interglacial period, with improved understanding of its primary cause or causes, and (2) using the geologic record, reconstruct the climate of the last interglacial period in the U.S. Both of these goals are intended to provide a basis for improvement of atmospheric general circulation models (AGCMs) that are critical for modeling of future climate.

Quantitative Models and Carbon Dynamics — Bruce Wylie
   Climate change has strong influences on high-latitude ecosystems. These habitats contain significant carbon stocks that may become sources for greenhouse gases to the atmosphere in a warming climate. Long-term ecosystem changes are expected with warming, changes in precipitation, and disturbances such as wildfires. We seek to understand and quantify disturbances and other changes in boreal forests by mapping differences between observed and weather-based predictions of boreal forest productivity (performance anomalies). Areas of changing ecosystems and disturbances are identified using time series maps. Histories of lake surface areas give clues to changing hydrology, connectivity to ground water, climate, water chemistry, important wildlife habitat, and sources of carbon efflux. Above-ground biomass quantification and mapping provide detailed information about carbon stocks and ecosystem productivity for biogeochemical modeling and prediction of future ecosystem responses. Below-ground soil organic layer and fall active layer depth are important ecological drivers and indicators. Below-ground remote sensing of near-surface electromagnetic resistivity gives important clues into the spatial distributions of important ecological drivers such as soil organic layers and active layers above permafrost.

Why is this research important?
   Boreal forest disturbances and ecological changes give indications of stress and potential vulnerability to long-term ecosystem shifts. Post-fire vegetation recovery can be tracked to highlight significant and unexpected deviations. Models for predicting undisturbed boreal forest productivity using weather and site conditions can also provide estimates of future boreal forest response to scenarios of future climate. Observations of surface water dynamics can be combined with measurement of deeper electromagnetic resistivity to quantify ground water connectivity to lakes and to improve regional ground water modeling and projections. Mapping of exposed lake shore sediments can be used in regional estimates of carbon dioxide and methane efflux. Predictions of waterfowl habitat and water chemistry can be based on observed relationships to surface water histories. Aboveground biomass maps provide an important input for carbon flux models, vegetation models, carbon stock quantification, and ecosystem mapping. Surface electromagnetic surveys provide the ability to map soil organic and active layer thicknesses, which are very important to post-fire succession trends, vegetation changes, and hydrologic changes. This research provides fundamental information needed to understand and predict boreal forest response to climate change and disturbances such as fires and insect invasions.

Rio Puerco Basin Studies — Milan Pavich
   The arroyo cycle and climate change are of scientific and practical interest. The Rio Puerco Basin, New Mexico, is an area of historic arroyo incision, long-term geomorphic investigation, and ongoing land management issues. This website comprises earth science and historical perspectives of the Rio Puerco Basin, and data and models that can be used to help predict responses to future changes of climate and landuse.

Snowmastodon Project — Jeff Pigati
   Complete ancient, high-elevation ecosystems are rarely preserved across glaciations. In fact, prior to discover of the Snowmastodon site in the Rocky Mountains of Colorado, no multi-proxy biotic records from the Sangamon Interglacial (125,000-75,000 years before present [yrBP]) were known from elevations greater than 1,000 m in North America. In 2010, construction to enlarge a reservoir at 2,720 m in the Colorado Rockies revealed a series of stacked Sangamonian ecosystems with abundant and exceptionally well-preserved plant, invertebrate, and vertebrate remains. Scientists and volunteers from the Denver Museum of Nature & Science recovered more than 5000 bones in two short field seasons ending in July 2011. The fossils included at least seven large mammals: American mastodon, the giant Bison latifrons, Jefferson's ground sloth, Columbian mammoth, ice-age deer, horse, and camel, as well as a number of smaller animals—rodents, salamanders, reptiles, snakes, fish, and birds. In addition to the vertebrate fossils, the site is host to exceptionally well-preserved plant, insect and aquatic invertebrate fossils — beetle parts are iridescent, plants are still green, and conifer cones are intact. The Snowmastodon site provides an unparalleled long-term record of biodiversity and climate change in the high-elevation Rocky Mountains.

Why is this research important?
   Analysis of pollen and plant macrofossils show major vegetation changes occurred here several times between ~130,000 and 50,000 yrBP, a period that includes the Sangamon Interglacial period. Climate conditions during Sangamonian times are closely analogous to projected future conditions for the region. Understanding how these fragile, high-elevation ecosystems responded to climate change in the past allows us to better prepare for the future.