Climate in the United States is expected to change during the 21st century, and soil erosion rates may be expected to change in response to changes in climate for a variety of reasons. This study was undertaken to investigate potential impacts of climate change on soil erosion by water. Erosion at eight locations in the United States was modeled using the Water Erosion Prediction Project model modified to account for the effects of atmospheric CO2 concentrations on plant growth. Simulated climate data from the U.K. Meteorological Office's Hadley Centre HadCM3 Global Circulation Model were used. The results indicated a complex set of interactions between the several factors that affect the erosion process. Direct effects of rainfall increases and decreases to runoff and erosion increases and decreases were observed but were often not dominant. One of the key factors of change in the system was the biomass production. Changes in soil moisture, atmospheric CO2 concentration, temperature, and solar radiation each impacted the biomass production at differing levels at the eight different sites. Different types of changes occurring at different periods of the year also complicated the response of the system. Overall, these results suggest that where precipitation increases are significant, erosion can be expected to increase. Where precipitation decreases occur, the results may be more complex due largely to interactions of plant biomass, runoff, and erosion, and either increases or decreases in overall erosion may be expected.