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
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
The Missouri River Basin (MRB) is the only major river headwaters in the western U.S. for which hydrologic reconstructions from tree rings have not been generated in any systematic way. This knowledge gap is critical given that the region is facing an array of water resource issues that are challenged by hydrologic variability – experiencing both severe floods and droughts in the recent past. Providing a longer context for understanding past variability of flow and the climatic controls on it, particularly at decadal and longer time scales, is critical for anticipating and managing future water supplies. Historical discharge records are too short for such assessments; hence, the value of tree-ring based hydrologic reconstructions that span the past several centuries to millennium.
The purpose of this project is to investigate Colorado River basin droughts, and the climatic factors that influence those droughts. The project uses paleoclimatic data to extend instrumental climate and flow records, along with climate change projections to assess the range of possible conditions that may be expected to occur and to determine how warming temperatures may influence river flow and water supply in the future.
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 Rocky Mountain Science Center (NOROCK), 2) the National Science Foundation (NSF) Paleo Perspectives on Climate Change (P2C2), Geography and Spatial Sciences (GSS), and Division of Environmental Biology Programs (DEB), and 3) The National Oceanic and Atmospheric Administration (NOAA).
A global multiproxy database for temperature reconstructions of the Common Era
Reproducible climate reconstructions of the Common Era (1 CE to present) are key to placing industrial-era warming into the context of natural climatic variability. Here we present a community-sourced database of temperature-sensitive proxy records from the PAGES2k initiative. The database gathers 692 records from 648 locations, including all...Emile-Geay, Julian; McKay, Nicholas P.; Kaufman, Darrell S.; von Gunten, Lucien; Wang, Jianghao; Anchukaitis, Kevin J.; Abram, Nerilie J.; Addison, Jason A.; Curran, Mark A.J.; Evans, Michael N.; Henley, Benjamin J.; Hao, Zhixin; Martrat, Belen; McGregor, Helen V.; Neukom, Raphael; Pederson, Gregory T.; Stenni, Barbara; Thirumalai, Kaustubh; Werner, Johannes P.; Xu, Chenxi; Divine, Dmitry V.; Dixon, Bronwyn C.; Gergis, Joelle; Mundo, Ignacio A.; Nakatsuka, T.; Phipps, Steven J.; Routson, Cody C.; Steig, Eric J.; Tierney, Jessica E.; Tyler, Jonathan J.; Allen, Kathryn J.; Bertler, Nancy A. N.; Bjorklund, Jesper; Chase, Brian M.; Chen, Min-Te; Cook, Ed; de Jong, Rixt; DeLong, Kristine L.; Dixon, Daniel A.; Ekaykin, Alexey A.; Ersek, Vasile; Filipsson, Helena L.; Francus, Pierre; Freund, Mandy B.; Frezzotti, M.; Gaire, Narayan P.; Gajewski, Konrad; Ge, Quansheng; Goosse, Hugues; Gornostaeva, Anastasia; Grosjean, Martin; Horiuchi, Kazuho; Hormes, Anne; Husum, Katrine; Isaksson, Elisabeth; Kandasamy, Selvaraj; Kawamura, Kenji; Koc, Nalan; Leduc, Guillaume; Linderholm, Hans W.; Lorrey, Andrew M.; Mikhalenko, Vladimir; Mortyn, P. Graham; Motoyama, Hideaki; Moy, Andrew D.; Mulvaney, Robert; Munz, Philipp M.; Nash, David J.; Oerter, Hans; Opel, Thomas; Orsi, Anais J.; Ovchinnikov, Dmitriy V.; Porter, Trevor J.; Roop, Heidi; Saenger, Casey; Sano, Masaki; Sauchyn, David; Saunders, K.M.; Seidenkrantz, Marit-Solveig; Severi, Mirko; Shao, X.; Sicre, Marie-Alexandrine; Sigl, Michael; Sinclair, Kate; St. George, Scott; St. Jacques, Jeannine-Marie; Thamban, Meloth; Thapa, Udya Kuwar; Thomas, E.; Turney, Chris; Uemura, Ryu; Viau, A.E.; Vladimirova, Diana O.; Wahl, Eugene; White, James W. C.; Yu, Z.; Zinke, Jens
Reassessment of the Upper Fremont Glacier ice-core chronologies by synchronizing of ice-core-water isotopes to a nearby tree-ring chronology
The Upper Fremont Glacier (UFG), Wyoming, is one of the few continental glaciers in the contiguous United States known to preserve environmental and climate records spanning recent centuries. A pair of ice cores taken from UFG have been studied extensively to document changes in climate and industrial pollution (most notably, mid-19th century...Chellman, Nathan J.; McConnell, Joseph R.; Arienzo, Monica; Pederson, Gregory T.; Aarons, Sarah; Csank, Adam
Reconstructions of Columbia River streamflow from tree-ring chronologies in the Pacific Northwest, USA
We developed Columbia River streamflow reconstructions using a network of existing, new, and updated tree-ring records sensitive to the main climatic factors governing discharge. Reconstruction quality is enhanced by incorporating tree-ring chronologies where high snowpack limits growth, which better represent the contribution of cool-season...Littell, Jeremy; Pederson, Gregory T.; Gray, Stephen T.; Tjoelker, Michael; Hamlet, Alan F.; Woodhouse, Connie A.
Coherent late-Holocene climate-driven shifts in the structure of three Rocky Mountain lakes
Large-scale atmospheric pressure centers, such as the Aleutian and Icelandic Low, have a demonstrated relationship with physical lake characteristics in contemporary monitoring studies, but the responses to these phenomena are rarely observed in lake records. We observe coherent changes in the stratification patterns of three deep (>30 m...Stone, Jeffery R.; Saros, Jasmine E.; Pederson, Gregory T.
The shifting climate portfolio of the Greater Yellowstone Area
Knowledge of climatic variability at small spatial extents (< 50 km) is needed to assess vulnerabilities of biological reserves to climate change. We used empirical and modeled weather station data to test if climate change has increased the synchrony of surface air temperatures among 50 sites within the Greater Yellowstone Area (GYA) of the...Sepulveda, Adam; Tercek, Mike T; Al-Chokhachy, Robert K.; Ray, Andrew; Thoma, David P.; Hossack, Blake R.; Pederson, Gregory T.; Rodman, Ann; Olliff, Tom
Climate-induced changes in lake ecosystem structure inferred from coupled neo- and paleoecological approaches
Over the 20th century, surface water temperatures have increased in many lake ecosystems around the world, but long-term trends in the vertical thermal structure of lakes remain unclear, despite the strong control that thermal stratification exerts on the biological response of lakes to climate change. Here we used both neo- and paleoecological...Saros, Jasmine E.; Stone, Jeffery R.; Pederson, Gregory T.; Slemmons, Krista; Spanbauer, Trisha; Schliep, Anna; Cahl, Douglas; Williamson, Craig E.; Engstrom, Daniel R.
The unusual nature of recent snowpack declines in the North American cordillera
In western North America, snowpack has declined in recent decades, and further losses are projected through the 21st century. Here, we evaluate the uniqueness of recent declines using snowpackreconstructions from 66 tree-ring chronologies in key runoff-...Pederson, Gregory T.; Gray, Stephen T.; Woodhouse, C.A.; Betancourt, Julio L.; Fagre, Daniel B.; Littell, Jeremy S.; Watson, Emma; Luckman, B.H.; Graumlich, Lisa J.
The continuum of hydroclimate variability in western North America during the last millennium
The distribution of climatic variance across the frequency spectrum has substantial importance for anticipating how climate will evolve in the future. Here we estimate power spectra and power laws (ß) from instrumental, proxy, and climate model data to characterize the hydroclimate continuum in western North America (WNA). We test the significance...Ault, Toby R.; Cole, Julia E.; Overpeck, Jonathan T.; Pederson, Gregory T.; St. George, Scott; Otto-Bliesner, Bette; Woodhouse, Connie A.; Deser, Clara
Regional patterns and proximal causes of the recent snowpack decline in the Rocky Mountains, U.S.
We used a first-order, monthly snow model and observations to disentangle seasonal influences on 20th century,regional snowpack anomalies in the Rocky Mountains of western North America, where interannual variations in cool-season (November–March) temperatures are broadly synchronous, but precipitation is typically antiphased north to south and...Pederson, Gregory T.; Betancourt, Julio L.; McCabe, Gregory J.
Leveraging modern climatology to increase adaptive capacity across protected area networks
Human-driven changes in the global environment pose an increasingly urgent challenge for the management of ecosystems that is made all the more difficult by the uncertain future of both environmental conditions and ecological responses. Land managers need strategies to increase regional adaptive capacity, but relevant and rapid assessment...Davison, J.E.; Graumlich, L.J.; Rowland, E.L.; Pederson, G.T.; Breshears, D.D.
Climate change links fate of glaciers and an endemic alpine invertebrate
Climate warming in the mid- to high-latitudes and high-elevation mountainous regions is occurring more rapidly than anywhere else on Earth, causing extensive loss of glaciers and snowpack. However, little is known about the effects of climate change on alpine stream biota, especially invertebrates. Here, we show a strong linkage between regional...Muhlfeld, Clint C.; Giersch, J. Joseph; Hauer, F. Richard; Pederson, Gregory T.; Luikart, Gordon; Peterson, Douglas P.; Downs, Christopher C.; Fagre, Daniel B.
An 1800-yr record of decadal-scale hydroclimatic variability in the upper Arkansas River basin from bristlecone pine
Bristlecone pine trees are exceptionally long-lived, and with the incorporation of remnant material have been used to construct multi-millennial length ring-width chronologies. These chronologies can provide valuable information about past temperature and moisture variability. In this study, we outline a method to build a moisture-sensitive...Woodhouse, C.A.; Pederson, G.T.; Gray, S.T.