Simulations of crop response to climate change: effects with present technology and no adjustments (the 'dumb farmer' scenario)

The climate of the 1930s-our analog of climate change-was imposed on farms representative of agriculture in the Missouri-Iowa-Nebraska-Kansas (MINK) region through the erosion productivity impact calculator (EPIC) model. Two levels of atmospheric CO₂ were considered: 350 and 450 ppm. No attempts to adjust or adapt the farms to the climate change were made. Results from simulations under the analog climate (1931-1940) were compared with results from simulations under the control climate (1951-1980). EPIC-simulated yields of warm-season crops were reduced by the analog climate. Yield reductions ranged from 7% for irrigated corn to 25% for dryland and soybeans. Simulated yields of dryland wheat were, on the whole, unchanged by the analog climate. Crops under irrigation fared better than dryland crops, although irrigation demand increased markedly. The simulated loss of crop yields under the analog climate was due to truncated growing seasons accompanied by reduced evapotranspiration. The higher level of atmospheric CO₂ alleviated simulated yield losses for all crops, although for corn and soybeans, particularly, yield losses remained significant.