Greg Pederson, Ph.D.
Biography
Education
Ph.D. Watershed Management & Ecohydrology. 2010. University of Arizona, School of Natural Resources.
M.S. Environmental Science. 2004. Montana State University
B.S. Ecology and Evolution in Botany & Zoology. 2000. Michigan State University
Research Interests
Greg Pederson is a research scientist working primarily on the role of climate variability in driving changes in water resources, and other biological and physical components of mountainous ecosystems in western North America. Of particular interest is the magnitude of low-frequency hydroclimatic variability and its implications for drought risk, as well as the climatic drivers associated with observed changes in mountain snowpack, streamflow, glaciers, and forest disturbance events. Understanding the time intervals and spatial scales over which these processes operate requires a long-term perspective, and for that I rely on proxy records primarily from tree-ring and lake sediments along with instrumental and modeled climate records. Recent and ongoing studies have addressed the susceptibility of natural resources to climate variability and change, and sought to apply both the modern and paleoclimatic records to present day resource management problems. Greg is affiliate faculty with the Earth Sciences department and the Institute on Ecosystems (IoE) at Montana State University. He grew up in Michigan and earned his B.S. in Ecology and Botany from Michigan State University, before moving to Montana to earn a M.S. from Montana State University. In 2010 he completed his Ph.D in watershed management and ecohydrology at the University of Arizona then returned to Bozeman Montana.
Current Research Projects Include:
- Drivers of Drought in the Upper Colorado River Basin [DOI Southwestern CSC]
- Multi-century perspectives on current and future streamflow in the Missouri River Basin [NSF P2C2]
- Reconstructions of Columbia River flow from winter and summer precipitation sensitive proxies in the Northwestern U.S. with implications for 21st century flow [CSC and CLU]
- A Broader view of North American climate over the past two millennia: Synthesizing paleoclimate records from diverse archives [USGS Powell Center]
- Holocene climate variability in Alaska from relict wood [DOI Alaska CSC]
- Holocene climates of the Northern Rockies from relict wood emerging from ice patches [CLU]
- Megadroughts and uncertainty in Upper Colorado River flow low-frequency variability [CLU]
Science and Products
Reconstructing Ancient Human and Ecosystem Responses to Holocene Climate Conditions
This research project will reconstruct Holocene climatic conditions to better understand human adaptation and response to past environmental variability.
Multi-century perspectives on current and future streamflow in the Missouri River Basin
The Missouri River system is the life-blood of the American Midwest providing water resources that drive agriculture, industry, hydroelectric power generation, and ecosystems. However, the Missouri River Basin (MRB) (Figure 1) is the only major river in the western U.S. for which hydrologic reconstructions from tree rings have not been generated in any systematic way. This knowledge gap is...
Drivers of Drought in the Upper Colorado River Basin
The purpose of this project is to investigate Colorado River basin droughts, and the role of temperature in influencing runoff efficiency. The project uses paleoclimatic data to extend instrumental climate and flow records, along with projected warming to assess the range of possible conditions that may be expected to occur and to determine how warming temperatures may influence river flow and...
Greg Pederson's Past Projects
This work is interdisciplinary and would not be possible without the collaboration of colleagues and their respective institutions. Research funding over the years has been provided by 1) the U.S. Geological Survey's National Research Program (NRP), the Climate and Land Use Program (CLU), the Southwestern and Alaska Climate Science Center, the Western Mountain Initiative (WMI), and the...
Broader view of North American climate over the past two millennia: Synthesizing paleoclimate records from diverse archives
Regional- to continental-scale paleoclimate syntheses of temperature and hydroclimate in North America are essential for understanding long-term spatiotemporal variability in climate, and for properly assessing risk on decadal and longer timescales. However, existing syntheses rely almost exclusively on tree-ring records, which are known to underestimate low-frequency variability and rarely...
Science and Forecasting to Inform Implementation of the Greater Yellowstone Coordinating Committee’s Whitebark Pine Management Strategy
The goal of this project was to inform implementation of the Greater Yellowstone Coordinating Committee (GYCC) Whitebark Pine (WBP) subcommittee’s “WBP Strategy” based on climate science and ecological forecasting. Project objectives were to: 1. Forecast ecosystem processes and WBP habitat suitability across the Greater Yellowstone Area (GYA) under alternative IPCC future scenarios; 2. Improve...
Integrating Climate and Biological Data into Management Decisions for the Greater Sage-Grouse and their Habitats
Climate affects both the demographics of the Greater sage-grouse bird and the condition and long-term viability of their habitats, including sage-steppe communities. This project builds on collaboration among federal land managers, state wildlife biologists, scientists, and other organizations to create a long-term framework for implementing adaptive management for the sage-grouse. The study...
Yellowstone's Old Faithful Geyser shut down by a severe 13th century drought
To characterize eruption activity of the iconic Old Faithful Geyser in Yellowstone National Park over past centuries, we obtained 41 new radiocarbon dates of mineralized wood preserved in the mound of silica that precipitated from erupted waters. Trees do not grow on active geyser mounds, implying that trees grew on the Old Faithful Geyser mound...
Hurwitz, Shaul; King, John; Pederson, Gregory T.; Martin, Justin; Damby, David; Manga, Michael; Hungerford, Jefferson; Peek, Sara Does signal-free detrending increase chronology coherence in large tree-ring networks?
Over the past decade, dendrochronologists have increasingly adopted the signal-free detrending (SFD) method to remove age-size trends in tree-ring measurement series, amplify the common stand-wide signal in composite chronologies, and recover medium- to low-frequency patterns that may be inadvertently removed by other detrending approaches....
McPartland, M.Y.; St. George, Scott; Pederson, Gregory T.; Anchukaitis, K.J. 2,200-Year tree-ring and lake-sediment based snowpack reconstruction for the northern Rocky Mountains highlights the historic magnitude of recent snow drought
In recent decades, Rocky Mountain accumulated snowpack levels have experienced rapid declines, yet long-term records of snowpack prior to the installation of snowpack observation stations in the early and mid 20th century are limited. To date, a small number of tree-ring based reconstructions of April 1 Snow Water Equivalent (SWE) in the northern...
Schoenemann, Spruce W.; Martin, Justin; Pederson, Gregory T.; McWethy, David B. Increased drought severity tracks warming in the United States’ largest river basin
Across the Upper Missouri River Basin, the recent drought of 2000 to 2010, known as the “turn-of-the-century drought,” was likely more severe than any in the instrumental record including the Dust Bowl drought. However, until now, adequate proxy records needed to better understand this event with regard to long-term variability have been lacking....
Martin, Justin; Pederson, Gregory T.; Woodhouse, Connie A.; Cook, Edward R.; McCabe, Gregory J.; Anchukaitis, Kevin J.; Wise, Erika K.; Erger, Patrick; Dolan, Larry S.; McGuire, Marketa; Gangopadhyay, Subhrendu; Chase, Katherine J.; Littell, Jeremy S.; Gray, Stephen; St. George, Scott; Friedman, Jonathan M.; Sauchyn, David J.; St. Jacques, Jeannine-Marie; King, John C. Millennial-scale climate and human drivers of environmental change and fire activity in a dry, mixed-conifer forest of northwestern Montana
Warm summer temperatures and longer fire seasons are promoting larger, and in some cases, more fires that are severe in low- and mid-elevation, dry mixed-conifer forests of the Northern Rocky Mountains (NRM). Long-term historical fire conditions and human influence on past fire activity are not well understood for these topographically and...
McWethy, David B.; Alt, Mio; Argiriadis, Elana; Battistel, Dario; Everett, Richard G.; Pederson, Gregory T. Dynamics, variability, and change in seasonal precipitation reconstructions for North America
Cool and warm season precipitation totals have been reconstructed on a gridded basis for North America using 439 tree-ring chronologies correlated with December-April totals and 547 different chronologies correlated with May-July totals. These discrete seasonal predictor chronologies are not significantly correlated with the alternate season and...
Stahle, David W.; Cook, Edward R; Burnette, Dorian J; Torbenson, Max C.A.; Howard, Ian M; Griffin, Daniel; Villanueva Diaz, Jose; Cook, Benjamin I.; Williams, Park A.; Watson, Emma; Sauchyn, David J.; Pederson, Neil; Woodhouse, Connie A.; Pederson, Gregory T.; Meko, David M.; Coulthard, Bethany; Crawford, Christopher J. Whitebark pine (Pinus albicaulis) growth and defense in response to mountain pine beetle outbreaks
Whitebark pine (Pinus albicaulis) is a critical forest species of Northern Rocky Mountain upper subalpine ecosystems, yet little is known about the physiological response of whitebark pine to disturbance (e.g. fire, bark beetles, and pathogens) across a range of diverse environmental gradients. Resin–based defenses have long been recognized as the...
Kichas, Nickolas E.; Hood, Sharon M.; Pederson, Gregory T.; Everett, Richard G.; McWethy, David B. 1200 years of Upper Missouri River streamflow reconstructed from tree rings
Paleohydrologic records can provide unique, long-term perspectives on streamflow variability and hydroclimate for use in water resource planning. Such long-term records can also play a key role in placing both present day events and projected future conditions into a broader context than that offered by instrumental observations. However,...
Martin, Justin; Pederson, Gregory T.; Woodhouse, Connie A.; Cook, Edward R; McCabe, Gregory J.; Wise, Erika K.; Erger, Patrick; Dolan, Larry; McGuire, Marketa; Gangopadhyay, Subhrendu; Chase, Katherine J.; Littell, Jeremy S.; Gray, Stephen; St. George, Scott; Friedman, Jonathan M.; Sauchyn, David J.; St. Jacques, Jannine; King, John W. Streamflow reconstruction in the Upper Missouri River Basin using a novel Bayesian network model
A Bayesian model that uses the spatial dependence induced by the river network topology, and the leading principal components of regional tree-ring chronologies for paleo-streamflow reconstruction is presented. In any river basin, a convergent, dendritic network of tributaries comes together to form the main stem of a river. Consequently, it is...
Ravindranath, Arun; Devineni, Naresh; Lall, Upmanu; Cook, Edward; Pederson, Gregory T.; Martin, Justin; Woodhouse, Connie A. An integrated framework for ecological drought across riverscapes of North America
Climate change is increasing the severity and extent of extreme droughts events, posing a critical threat to freshwater ecosystems, particularly with increasing human demands for diminishing water supplies. Despite the importance of drought as a significant driver of ecological and evolutionary dynamics, current understanding of drought...
Kovach, Ryan; Dunham, Jason B.; Al-Chokhachy, Robert; Snyder, Craig; Beever, Erik A.; Pederson, Gregory T.; Lynch, Abigail; Hitt, Nathaniel P.; Konrad, Christopher P.; Jaeger, Kristin; Rea, Alan H.; Sepulveda, Adam J.; Lambert, Patrick M.; Stoker, Jason M.; Giersch, J. Joseph; Muhlfeld, Clint C. Risks of hydroclimatic regime shifts across the western United States
Paleohydrologic reconstructions of water-year streamflow for 105 sites across the western United States (West) were used to compute the likelihood (risk) of regime (wet/dry state) shifts given the length of time in a specific regime and for a specified time in the future. The spatial variability of risks was examined and indicates that regime...
Gangopadhyay, Subhrendu; McCabe, Gregory J.; Pederson, Gregory T.; Martin, Justin; Littell, Jeremy S. Changing station coverage impacts temperature trends in the Upper Colorado River Basin
Over the Upper Colorado River Basin (UCRB), temperatures in widely used gridded data products do not warm as much as mean temperatures from a stable set of U.S. Historical Climatology Network (USHCN) stations, located at generally lower elevations, in most months of the year. This is contrary to expectations of elevation-dependent warming, which...
McAfee, Stephanie A.; McCabe, Gregory J.; Gray, Stephen; Pederson, Gregory T.
A time when Old Faithful wasn’t so faithful
Old Faithful Geyser got its unique name in the 19th century because its eruptions were so regular and predictable. But during parts of the 13th and 14th centuries, the geyser did not erupt at all.