Any change in climate will have implications for climate-sensitive systems such as agriculture, forestry, and some other natural resources. With respect to agriculture, changes in solar radiation, temperature, and precipitation will produce changes in crop yields, crop mix, cropping systems, scheduling of field operations, grain moisture content at harvest, and hence, on the economics of agriculture including changes in farm profitability. Such issues are addressed for 10 representative agricultural areas across the midwestern Great Lakes region, a five-state area including Indiana, Illinois, Ohio, Michigan, and Wisconsin. This region is one of the most productive and important agricultural regions in the world, with over 61% of the land use devoted to agriculture. Individual crop growth processes are affected differently by climate change. A seasonal rise in temperature will increase the developmental rate of the crop, resulting in an earlier harvest. Heat stress may result in negative effects on crop production. Conversely, increased rainfall in drier areas may allow the photosynthetic rate of the crop to increase, resulting in higher yields. Properly validated crop simulation models can be used to combine the environmental effects on crop physiological processes and to evaluate the consequences of such influences. With existing hybrids, an overall pattern of decreasing crop production under scenarios of climate change was found, due primarily to intense heat during the main growth period. However, the results changed with the hybrid of maize (Zen Inngs L.) being grown and the specific location in the study region. In general, crops grown in sites in northern states had increased yields under climate change, with those grown in sites in the southern states of the region having decreased yields under climate change. Yields from long-season maize increased significantly in the northern part of the study region under future climate change. Across the study region, long-season maize performed most successfully under future climate scenarios compared to current yields, followed by medium-season and then short-season varieties. This analysis highlights the spatial variability of crop responses to changed environmental conditions. In addition, scenarios of increased climate variability produced diverse yields on a year-to-year basis and had increased risk of a low yield. Results indicate that potential future adaptations to climate change for maize yields would require either increased tolerance of maximum summer temperatures in existing maize varieties or a change in the maize varieties grown. (C) 2000 Elsevier Science B.V. All rights reserved.
Southworth, J; Randolph, JC; Habeck, M; Doering, OC; Pfeifer, RA; Rao, DG; Johnston, JJ
Consequences of future climate change and changing climate variability on maize yields in the midwestern United States
Agriculture Ecosystems & Environment