USGS Contributions to the Climate Change Science Program

Vegetation changes caused by climatic variations and/or land use may have large impacts on forests, agriculture, rangelands, natural ecosystems, and endangered species. Climate modeling studies indicate that vegetation cover, in turn, has a strong influence on regional climates, and this must be better understood before models can estimate future environmental conditions. To address these issues, the USGS is investigating vegetational response to climatic change, and vegetation-land surface impacts on climate change.
The project involves calibration of the modern relations between the range limits of plant species and climatic variables that are then used to

• estimate past climatic fluctuations from paleobotanical data for a number of time periods within the late Quaternary
• 'validate' climate model simulations of past climates
• explore the potential influences of land cover changes on climate change
• estimate the potential future ranges of plant species under a number of future climate scenarios

Shown here is the modern distribution of Douglas fir (Pseudotsuga menziesii) and the potential distribution under a simulated future "greenhouse" climate with carbon dioxide levels twice those of pre-industrial times (a "2xCO2" climate). Green represents sites where the species lives today (left panel) and where it could continue to live under the 2xCO2 simulated climate (right panel). Red indicates where it could not survive under the 2xCO2 simulated climate. Blue represents sites where it cannot live today but potentially could live under the simulated future conditions.

Present Climate Present CO2 Biomes 1951-1980, 340 ppm CO2	Future Climate Future CO2 Biomes 2050-2059, 554 ppm CO2
Model: BIOME4, ver. 2 (Kaplan & Prentice, 1999)