Gassman, Philip (Iowa State University, 560E Heady Hall, Center for Agric, Ames, IA, 50011-1070; Phone: 515-294-6313; Fax: 515-294-6336; Email: pwgassma@iastate.edu)

Climate Change Projection Impact on Soil Carbon and Other Environmental Indicators for the Upper Mississippi River Basin

P.W. Gassman *, C.J. Anderson, G.S. Takle, M.K. Jha, R.M. Cruse

Coupled atmosphere-ocean models project future climate changes in response to changes in forcing due to greenhouse gas increases, changes in atmospheric aerosol concentrations, and land-use changes. Results of these models are used either directly or indirectly (by driving regional climate models) to project changes in hydrologic responses of watershed systems and crop growth. However, comparatively few studies have assesses impacts of climate change on soil organic carbon (SOC) sequestration and related environmental indicators. Our goal is to provide an initial assessment of a new climate change projection on SOC sequestration and other environmental impacts such as soil erosion losses for the Upper Mississippi River Basin. We use climate change projections generated by the Goddard Institute for Space Studies (GISS) 4ox3o Atmospheric-Ocean Model (AOM), which will be used as part of the 2007 IPCC climate change analysis. SRES scenarios “A1B” and “B1”, corresponding to atmospheric CO2 concentration levels 2.0 and 1.5 times as much of the 2000 level, respectively, are used for our analysis. We compare conditions for a future climate period of 2081-2100 with those of a 20th century “contemporary climate” baseline represented by the period 1961-2000. SOC sequestration, soil erosion rates, and other environmental indicators will be estimated with an enhanced version of the Environmental Policy Impact Climate (EPIC) model, which includes a carbon cycling routine based on the approach used in the Century model. The EPIC simulations will be performed within an existing modeling framework developed at the Center for Agricultural and Rural Development for over 40,000 agriculturally related points, as identified in the 1997 National Resource Inventory (NRI). Changes in SOC and other environmental indicators will be aggregated to the USGS 8-digit watershed level and will be reported as relative changes between the two future climate scenarios and the 20th century baseline.