Predictions of future climate and atmospheric conditions are reviewed and the implications for agriculture in different areas of the world are identified. The SWOPSIM (static world policy simulation) model used to evaluate the worldwide economic effects of climate change is described. An economic sensitivity analysis of concurrent yield losses in major grain-producing regions considering the possibility of concurrent changes in production potential elsewhere in the world is reported. Agricultural impacts of climate change based on three general circulation models are evaluated.

The federal tax code provides preferential treatment for the production and use of renewable energy. We report estimates of the subsidies' effects on greenhouse gases (GHG) emissions developed in a recent National Research Council (NRC) Report. Due to lack of estimates of the impact of tax provisions on GHG emissions, new modeling studies were commissioned. The studies found, at best, a small impact of subsidies in reducing GHG emissions; in some cases, emissions increased. The NRC report also identified the need to capture the complex interactions among subsidies, pre-existing regulations, and commodity markets.