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.
Research Interests
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.
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]
Education and Certifications
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
Affiliations and Memberships*
Greg is affiliate faculty with the Earth Sciences department and the Institute on Ecosystems (IoE) at Montana State University.
Science and Products
Reconstructing Ancient Human and Ecosystem Responses to Holocene Climate Conditions
Multi-century perspectives on current and future streamflow in the Missouri River Basin
Characterizing Historic Streamflow to Support Drought Planning in the Upper Missouri River Basin
Anticipating Future Impacts of Temperature on Streamflow in the Colorado River Basin
Drivers of Drought in the Upper Colorado River Basin
Greg Pederson's Past Projects
Examining the Influence of Temperature and Precipitation on Colorado River Water Resources: Reconstructing the Past to Understand the Future
Broader view of North American climate over the past two millennia: Synthesizing paleoclimate records from diverse archives
Science and Forecasting to Inform Implementation of the Greater Yellowstone Coordinating Committee’s Whitebark Pine Management Strategy
Integrating Climate and Biological Data into Management Decisions for the Greater Sage-Grouse and their Habitats
Radiocarbon dating of silicified wood from around Steamboat Geyser in Norris Geyser Basin, Yellowstone National Park, 2021-2022
Cool Season (September-June) Total Precipitation Reconstruction for Deschutes County, Oregon, 1000-1991 CE
A network of eight naturalized streamflow reconstructions for the Milk and St Mary Rivers spanning years 1017 - 1998 CE
Tree ring dataset for a regional avalanche chronology in northwest Montana, 1636-2017
A network of 31 Upper Missouri River Basin naturalized water-year (Oct-Sep) streamflow reconstructions spanning years 800 - 1998 CE
Paleohydrologic reconstructions of water-year streamflow for 31 stream gaging sites in the Missouri River Basin with complete data for 1685 through 1977
Multi-century reconstructions of temperature, precipitation, and runoff efficiency for the Upper Colorado River Basin
Big avalanches in a changing climate: Using tree-ring derived avalanche chronologies to examine avalanche frequency across multiple climate types
Using tree rings to compare Colorado’s 2019 avalanche cycle to previous large avalanche cycles
The relation between decadal droughts and eruptions of Steamboat Geyser in Yellowstone National Park, USA
Increased whitebark pine (Pinus albicaulis) growth and defense under a warmer and regionally drier climate
Streamflow reconstructions from tree rings and variability in drought and surface water supply for the Milk and St. Mary River basins
Climate and landscape controls on old-growth western juniper demography in the northern Great Basin, USA
Greater Yellowstone climate assessment: Past, present, and future climate change in the greater Yellowstone watersheds
Broad-scale surface and atmospheric conditions during large fires in south-central Chile
Climate drivers of large magnitude snow avalanche years in the U.S. northern Rocky Mountains
Growth and defense characteristics of whitebark pine (Pinus albicaulis) and lodgepole pine (Pinus contorta var latifolia) in a high-elevation, disturbance-prone mixed-conifer forest in northwestern Montana, USA
Water reliability in the west -- SECURE Water Act Section 9503(C)
A regional spatio-temporal analysis of large magnitude snow avalanches using tree rings
Science and Products
- Science
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...Characterizing Historic Streamflow to Support Drought Planning in the Upper Missouri River Basin
The Missouri River system is the life-blood of the American Midwest, providing critical water resources that drive the region’s agriculture, industry, hydroelectric power generation, and ecosystems. The basin has a long history of development and diversion of water resources, meaning that streamflow records that reflect natural, unmanaged flows over the past century have been rare. As a result, re...Anticipating Future Impacts of Temperature on Streamflow in the Colorado River Basin
The Colorado River is a crucial water source for millions of people in the Southwest. Warming temperatures, clearly documented in climate records for the Colorado River basin, are having an impact on the amount of annual streamflow yielded from rain and snow. Recent work has revealed that warming temperatures have played an increasingly important role over the past decades, both exacerbating drougDrivers 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 Northern...Examining the Influence of Temperature and Precipitation on Colorado River Water Resources: Reconstructing the Past to Understand the Future
Streamflow in the Colorado River is heavily influenced by high-elevation snowpack. Warming temperatures in spring can reduce snow-fed flows, with serious implications for the water supplies that support communities and wildlife. While it is already well-known that precipitation has a significant influence on river flow, recent observations suggest that temperature and the amount of water in soil mBroader 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 extendScience 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 und...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 exami - Data
Radiocarbon dating of silicified wood from around Steamboat Geyser in Norris Geyser Basin, Yellowstone National Park, 2021-2022
In the past century, eruptions of Steamboat Geyser in Yellowstone’s Norris Geyser Basin were mainly clustered in three episodes: between 1961 and 1969, between 1982 and 1984, and in a sequence of eruptions that began in 2018 (Reed et al., 2021) and resulted in extensive damage to, and mortality of the surrounding trees. To characterize tree response to geyser activity over time, and the response oCool Season (September-June) Total Precipitation Reconstruction for Deschutes County, Oregon, 1000-1991 CE
A tree-ring based cool season (September-June) total precipitation reconstruction for Deschutes County, Oregon, spanning years 1000-1991 CEA network of eight naturalized streamflow reconstructions for the Milk and St Mary Rivers spanning years 1017 - 1998 CE
Paleohydrologic records provide a valuable perspective on the variability of streamflow and hydroclimate that is critical for water resource planning and placing present day and future conditions into a long-term context. Until now, key insights gained from streamflow reconstructions in the other river basins across the Western U.S. have been lacking in the Milk and St. Mary River Basin. Here we uTree ring dataset for a regional avalanche chronology in northwest Montana, 1636-2017
This dataset includes processed tree ring data from avalanche paths in Glacier National Park and the Flathead National Forest in northwest Montana. The data were processed in three distinct phases that resulted in this dataset: collection, processing, and avalanche signal analysis. This dataset consists of samples from 647 trees with 2304 growth disturbances identified from 12 avalanche paths.A network of 31 Upper Missouri River Basin naturalized water-year (Oct-Sep) streamflow reconstructions spanning years 800 - 1998 CE
Paleohydrologic records provide a valuable perspective on the variability of streamflow and hydroclimate that is critical for water resource planning and placing present day and future conditions into a long-term context. Until now, key insights gained from streamflow reconstructions in the other river basins across the Western U.S. been lacking in the Upper Missouri River Basin due to a lack of ePaleohydrologic reconstructions of water-year streamflow for 31 stream gaging sites in the Missouri River Basin with complete data for 1685 through 1977
Tree-ring reconstructions of water-year (Oct 1 through Sep 30th) flow for 31 gaging sites in Missouri River basin, with complete data for 1685 through 1977 (n = 293 water years). The complete 105 tree-ring reconstructions of streamflow used in the Nature Scientific Reports paper were obtained from various sources; 74 flow reconstructions were obtained from the web resource, TreeFlow (http://www.trMulti-century reconstructions of temperature, precipitation, and runoff efficiency for the Upper Colorado River Basin
With increasing concerns about the impact of warming temperatures on water resources, more attention is being paid the relationship between runoff and precipitation, or runoff efficiency. Temperature is a key influence on Colorado River runoff efficiency, and warming temperatures are projected to reduce runoff efficiency. Here, we investigate the nature of runoff efficiency in the upper Colorado R - Multimedia
- Publications
Filter Total Items: 57
Big avalanches in a changing climate: Using tree-ring derived avalanche chronologies to examine avalanche frequency across multiple climate types
Large-magnitude snow avalanches pose a hazard to humans and infrastructure worldwide. Analyzing the spatiotemporal behavior of avalanches and the contributory climate factors is important for understanding historical variability in climate-avalanche relationships as well as improving avalanche forecasting. This study uses established dendrochronological methods to develop long-term regional avalanAuthorsErich Peitzsch, Gregory T. Pederson, Justin Martin, Eran Hood, Ethan Greene, Karl Birkeland, Kelly Elder, Gabriel Wolken, Nickolas E. Kichas, Daniel Kent Stahle, John HarleyUsing tree rings to compare Colorado’s 2019 avalanche cycle to previous large avalanche cycles
Large magnitude avalanches (size ≥D3) impact settlements, transportation corridors, and public safety worldwide. In Colorado, United States, avalanches have killed more people than any other natural hazard since 1950. In March 2019, a historically large magnitude avalanche cycle occurred throughout the entire mountainous portion of Colorado resulting in more than 1000 reported avalanches during aAuthorsErich Peitzsch, Ethan Greene, Jason Konigsberg, Gregory T. Pederson, Justin Martin, Nickolas Kichas, Daniel Kent Stahle, Adrien Favillier, Nicolas Eckert, Karl Birkeland, Kelly ElderThe relation between decadal droughts and eruptions of Steamboat Geyser in Yellowstone National Park, USA
In the past century, most eruptions of Steamboat Geyser in Yellowstone National Park's Norris Geyser Basin were mainly clustered in three episodes: 1961–1969, 1982–1984, and ongoing since 2018. These eruptive episodes resulted in extensive disturbance to surrounding trees. To characterize tree response over time as an indicator of geyser activity adjustments to climate variability, aerial and grouAuthorsShaul Hurwitz, John C. King, Gregory T. Pederson, Mara H. Reed, Lauren N Harrison, Jefferson Hungerford, R. Greg Vaughan, Michael MangaIncreased whitebark pine (Pinus albicaulis) growth and defense under a warmer and regionally drier climate
Introduction: Tree defense characteristics play a crucial role in modulating conifer bark beetle interactions, and there is a growing body of literature investigating factors mediating tree growth and resin-based defenses in conifers. A subset of studies have looked at relationships between tree growth, resin duct morphology and climate; however, these studies are almost exclusively from lower-eleAuthorsNicholas E. Kichas, Gregory T. Pederson, Sharon M. Hood, Richard G. Everett, David B. McWethyStreamflow reconstructions from tree rings and variability in drought and surface water supply for the Milk and St. Mary River basins
The Milk and St. Mary Rivers are international waterways straddling the United States and Canada and traversing four Tribal Nations before draining into the Missouri and South Saskatchewan Rivers respectively. Management of water resources in the region is challenged by the complexity of stakeholder interests, the limitations of existing management infrastructure, and by a limited characterizationAuthorsJustin Martin, Gregory T. PedersonClimate and landscape controls on old-growth western juniper demography in the northern Great Basin, USA
Western juniper (Juniperus occidentalis Hook.) woodlands have persisted for millennia in semiarid parts of the northern Great Basin, USA, providing critical habitat for plant and animal species. Historical records suggest that the establishment of western juniper is strongly associated with regional climatic variability. For example, the abundance of western juniper pollen and macrofossils measureAuthorsRachel A. Loehman, Emily K. Heyerdahl, Gregory T. Pederson, David B. McWethyGreater Yellowstone climate assessment: Past, present, and future climate change in the greater Yellowstone watersheds
The Greater Yellowstone Area (GYA) is one of the last remaining large and nearly intact temperate ecosystems on Earth. GYA was originally defined in the 1970s as the Greater Yellowstone Ecosystem, which encompassed the minimum range of the grizzly bear. The boundary now includes about 22 million acres (8.9 million ha) in northwestern Wyoming, south central Montana, and eastern Idaho (Figure ES-1).AuthorsSteven W. Hostetler, Cathy Whitlock, Bryan Shuman, David Liefert, Charles Wolf Drimal, Scott BischkeBroad-scale surface and atmospheric conditions during large fires in south-central Chile
The unprecedented size of the 2017 wildfires that burned nearly 600,000 hectares of central Chile highlight a need to better understand the climatic conditions under which large fires develop. Here we evaluate synoptic atmospheric conditions at the surface and free troposphere associated with anomalously high (active) versus low (inactive) months of area burned in south-central Chile (ca. 32–41° SAuthorsDavid B. McWethy, René Garreaud, Andrés Holz, Gregory T. PedersonClimate drivers of large magnitude snow avalanche years in the U.S. northern Rocky Mountains
Large magnitude snow avalanches pose a hazard to humans and infrastructure worldwide. Analyzing the spatiotemporal behavior of avalanches and the contributory climate factors is important for understanding historical variability in climate-avalanche relationships as well as improving avalanche forecasting. We used established dendrochronological methods to develop a long-term (1867–2019) regionalAuthorsErich Peitzsch, Gregory T. Pederson, Karl W. Birkeland, Jordy Hendrikx, Daniel B. FagreGrowth and defense characteristics of whitebark pine (Pinus albicaulis) and lodgepole pine (Pinus contorta var latifolia) in a high-elevation, disturbance-prone mixed-conifer forest in northwestern Montana, USA
Recent, widespread tree mortality in the western U.S. resulting from changes in climate, pathogens, insect activity, and forest management practices has led to concerns for many ecologically and culturally important species. Within conifers, resin-based defenses have long been recognized as a primary defense mechanism against a variety of insects and pathogens. Oleoresin produced by trees containAuthorsNicholas E. Kichas, Amy M. Trowbridge, Kenneth F. Raffa, Shealyn C. Malone, Sharon M. Hood, Richard G. Everett, David B. McWethy, Gregory T. PedersonWater reliability in the west -- SECURE Water Act Section 9503(C)
No abstract available.AuthorsMarketa McGuire, Subhrendu Gangopadhyay, Justin Martin, Gregory T. Pederson, Connie A. Woodhouse, Jeremy S. LittellA regional spatio-temporal analysis of large magnitude snow avalanches using tree rings
Snow avalanches affect transportation corridors and settlements worldwide. In many mountainous regions, robust records of avalanche frequency and magnitude are sparse or non-existent. However, dendrochronological methods can be used to fill this gap and infer historical avalanche patterns. In this study, we developed a tree-ring-based avalanche chronology for large magnitude avalanche events (sizeAuthorsErich Peitzsch, Jordy Hendrikx, Daniel Kent Stahle, Gregory T. Pederson, Karl W. Birkeland, Daniel B. Fagre - News
*Disclaimer: Listing outside positions with professional scientific organizations on this Staff Profile are for informational purposes only and do not constitute an endorsement of those professional scientific organizations or their activities by the USGS, Department of the Interior, or U.S. Government