Climate Research and Development ProgramClimate R&D Program

Terrestrial Rates and Amplitudes of Changes in Ecoclimate Systems (TRACES)

Picture of a boat on a mountain lake.

The TRACES project reconstructs changes in the distributions of plant species and ecosystems in the western United States for the past 25,000 years, based on fossil pollen and plant macrofossils. These data are combined with information on the present-day relations between climatic parameters and plant distributions to produce estimates of the nature, amplitude, and timing of paleoclimatic changes in this physiologically and climatically complex region. This work reveals past geographic patterns in temperature and moisture parameters that can then be related to likely changes in atmospheric circulation, and that provide ground truth for numerical model simulations of climatic conditions different from those of today. This research also provides the basis for assessing the sensitivity of individual plant species and ecosystems to a range of different changes in climatic conditions. Current efforts include completion of an atlas on the modern relations between climate and plant distributions across North America, quantitative reconstructions of climatic changes in arid and semiarid lands from the last ice age to the present, and changes in upper and lower treelines in the mountains of Colorado over the past 10,000 years.

Why is this research important?

The western United States has a rapidly growing human population, limited water resources, and a large percentage of public lands. Understanding the sensitivity of plant species and ecosystems to specific kinds of climatic changes provides a basis for evaluating the potential effects of ongoing and future climatic changes on plant communities and other resources in this region.

Project Lead: Bob Thompson
Project Team: Kathy Anderson, Paul Carrara, Richard Pelltier, Laura Strickland

7 publications matching the specified parameters were found.

Strickland, L.E., Baker, R.G., Thompson, R.S., and Miller, D.M., 2014, Last interglacial plant macrofossils and climates from Ziegler Reservoir, Snowmass Village, Colorado, USA: Quaternary Research, v. 82, no. 3, p. 553-566.

Arthur, M.A. and Dean, W.E., 2013, Oceanographic controls on sedimentary and geochemical facies on the Peru outer shelf and upper slope: Geological Survey, Open-File Report 2013-1105, 38 p.
Available at:

Burkett, V.R., Kirtland, D.A., Taylor, I.L., Belnap, Jayne, Cronin, T.M., Dettinger, M.D., Frazier, E.L., Haines, J.W., Loveland, T.R., Milly, P.C.D., O'Malley, Robin, Thompson, R.S., Maule, A.G., McMahon, Gerard, and Striegl, R.G., 2013, U.S. Geological Survey climate and land use change science strategy - A framework for understanding and responding to global change: U.S. Geological Survey Circular 1383-A, 43 p.
Available at:

Wang, C., Scott, R.W., Wan, X., Graham, S.A., Yongjian, H., Wang, P., Wu, H., Dean, W.E., and Zhang, L., 2013, Late Cretaceous climate changes recorded in Eastern Asian lacustrine deposits and North American epieric sea changes: Earth-Science Reviews, v. 126, p. 275-299.

Thompson, R.S., Anderson, K.H., Pelltier, R.T., Strickland, L.E., Bartlein, P.J., and Shafer, S.L., 2012, Quantitative estimation of climatic parameters from vegetation data in North America by the Mutual Climatic Range technique: Quaternary Science Reviews, v. 51, p. 18-39.

Thompson, R.S., Anderson, K.H., Pelltier, R.T., Strickland, L.E., Shafer, S.L., and Bartlein, P.J., 2012, Atlas of relations between climatic parameters and distributions of important trees and shrubs in North America - Modern data for climatic estimation from vegetation inventories, U.S. Geological Survey Professional Paper 1650-F, CD-ROM.
Available at:

Burkett, V., Taylor, I.L., Belnap, J., Cronin, T.M., Dettinger, M.D., Frazier, E.L., Haines, J.W., Kirtland, D.A., Loveland, T.R., Milly, P.C.D., O'Malley, R., and Thompson, R. S., 2011, USGS Global Change Science Strategy: A Framework for Understanding and Responding to Climate and Land-Use Change: USGS Open-File Report 2011-1033.

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