Over the last decade, scientists have extensively studied the greenhouse effect, which holds that the accumulation of carbon dioxide (C 0 2) and other greenhouse gases (GHG’s) is expected to produce global warming and other significant climatic changes over the next century. Numerous studies indicate major impacts on agriculture, especially if there is significant midcontinental drying and warming in the U.S. heartland.1 Virtually every estimate of economic impacts relies on a technique we denote the production-function approach.