Using input from the June 1997 Southeast Regional Scoping workshop and follow-on meetings with other regional stakeholders, an interdisciplinary research team was organized to conduct a Regional Assessment of the implications of climate variability and change on agriculture, forests, environmental quality (air and water), and the cross-cutting implications of water resources on these sectors. The assessment team includes researchers from Auburn University, Florida State University, North Carolina State University, Research Triangle Institute, University of Alabama (in Tuscaloosa and Huntsville), University of Florida, US Forest Service, and USDA’s Peanut Research Laboratory. The team also works closely with the Southern Growth Policies Board, Appalachian Regional Commission, state and local government agencies (i.e., Alabama Department of Economic Affairs), utility companies, and with the agricultural extension in several southeastern states. It is anticipated that these stakeholder relationships will be enhanced in the future as assessment results and new analytical methods and data become available. A brief summary of our progress to date is provided below.

Agriculture

Crop yield simulations with the Hadley (HadCM2) climate scenarios for the decades around 2030 and 2090 were performed using current management conditions for six key crops (corn, peanut, rice, soybean, sorghum, and winter wheat). County-level yield results and irrigation demand by crop were estimated for the entire southeastern US. As shown in Figure 1, there is considerable variability among crops with regard to their sensitivity to climate variations. Corn and sorghum, for example are particularly sensitive to higher temperatures. These maps also show the spatial variability in crop response across the Southeast. Preliminary results indicate that most negative effects are found in the Gulf Coast region. These crop responses will also be used in a USDA/ARS regional farm management model (PNTPLAN) to determine how farm managers might respond. Farm management optimization is being run for these crops using the climate-induced yield changes for 2030 and 2090 assuming a representative 200-acre farm with current crop mix and crop yield for each county. A full set of results for all locations and all six crops is expected by the end of 1999.

Forestry

As part of the regional assessment, the Hadley (HadCM2) climate scenarios were also applied to a forest productivity model (PnET-II) across the southeastern states. This forest process model combines climate, soil, and vegetation data to predict productivity, soil water stress, and drainage. Figure 2 shows results for pine and southern hardwoods comparing baseline conditions (2000) to 2090. Under baseline conditions southern pine productivity would be approximately 5% less than hardwood productivity, but by 2090 hardwoods would be about 27% more productive than pine forests across the southeast region. Pines have greater water demands than do hardwoods on an annual basis. Even with the increased water use efficiencies associated with increased atmospheric CO₂, the southern pines are limited by water as evapotranspiration rates increase with air temperatures. These responses, however, could likely be ameliorated since pine plantation managers would be able to adapt silvicultural techniques and species composition in response to climate change. The forest productivity results are being linked to the Sub-Regional Timber Supply model. This economic model uses relationships between prices, harvest, and inventory to suggest the market effects of shifts in supply or demand. We expect these economic results will become available over the next few months.

Water Quality
An assessment of southeastern water quality associated with changes in climate was conducted using EPA's GIS-based BASINS model to evaluate current and future water quality conditions under both mean and extreme hydologic conditions. The Hadley climate scenarios show significantly decreased precipitation during the first six months of the year with rainfall returning to normal, or near normal, for the last six months, particularly by the end of the century. These results are particularly striking for the Gulf Coast region and appear to indicate that this area may be exceptionally vulnerable to degraded conditions during the first half of the next century. Preliminary hydrologic analyses based on the Hadley (HadCM2) model predictions appear to confirm that streamflow in the Southeast (particularly along the Gulf Coast) will decline during the early summer months over the next 30 years. These results suggest that water quality conditions in this region may become critical during the more frequent periods of extreme low flow. Correlation of the hydrologic analyses with the land use in basins where water quality (i.e., dissolved oxygen, nitrates) have already been identified reveals that the problems may be most acute in areas of intensive agricultural activity, or in coastal or near coastal streams.

Integration

The most innovative feature of this assessment is the application of an integrated approach that links climate variability and change with crop yields, regional economics, and forest productivity and timber markets. The results of these linkages will then be used in a land use model to estimate economic incentives for land use conversions between agricultural and forest lands. Over the next few months, the Southeast Regional Assessment team plans to complete these analyses and document the results in a summary regional report. The next step in the overall assessment process will be to transfer this new understanding to relevant stakeholders in the region through education, data interpretation, and introduction of simplified analytical tools and other products that can be incorporated into existing decision-making processes at the local and regional levels. Meetings are already being planned with several state and local government agencies and with representatives from the agricultural sector (i.e. agricultural extension, farm cooperators, agribusiness) to identify specific assessment products that can be applied to local, state, and regional problems.

For more information, contact:

Ronald L Ritschard, Earth System Science Laboratory, Global Hydrology and Climate Center, University of Alabama; 977 Explorer Blvd., Huntsville, AL 35806; phone: (256) 922-5801; email: ron.ritschard@atmos.uah.edu