Washington, DC, USA
February 21, 2013
Source: USDA/ERS Amber Waves
by Scott Malcolm, Elizabeth Marshall, Paul Heisey, and Michael Livingston
Agricultural production has always been affected by variability in weather, and U.S. farmers have adopted production practices and strategies appropriate to their local climates. The weather that shapes the current structure of U.S. agricultural production, however, is changing as global climatic conditions change. Climate models predict worldwide increases in average temperatures, with wide-ranging effects on local temperature and rainfall. Whether such changes present a risk to food supplies and farmer livelihoods depends partly on the direction, magnitude, and rate of change but also on the responsiveness of farmers and ranchers to shifting conditions. Adaptive behaviors such as adjusting crop choices and production practices may help mitigate the negative effects of climate change and enable some producers to capitalize on new opportunities. Future developments in technology and policy are also likely to contribute to adaptive capacity.
The impacts of climate change on crop growth are both complex and uncertain. Although temperature increases associated with climate change are widely expected to lower yields for crops such as corn and soybeans, shifting regional precipitation patterns can either exacerbate or offset such yield impacts. Model results suggest that the negative effects of climate-induced yield changes on crop prices, farm revenue, and the food supply can be mitigated by the ability of farmers to adapt through their crop production decisions and use of technologies. Such changes, however, may be associated with increased environmental impacts. Changes in the distribution of pests will further magnify production and revenue losses, although innovations to improve the tolerance and suitability of crops under adverse climatic conditions may help to alleviate negative outcomes.
A recent ERS study analyzes the ability of U.S. crop producers to adapt to shifting yield and productivity patterns associated with future changes in temperature and precipitation, and the consequences of their adaptive responses for crop production and land use, crop markets, returns to producers, and water quality measures. The study employs four climate change scenarios for the year 2030, encompassing a range of projected regional changes in temperature and rainfall. The climate change scenarios are named for the climate models that produced them--ECH, CSIRO, CNR, and MIROC--with ECH projecting a future that is relatively cooler and wetter and MIROC projecting one that is relatively warmer and drier (see box, “Climate Scenarios”). The remaining two scenarios fall between these two extremes, with CSIRO generally being cooler and wetter than CNR. The analysis adjusted regional crop yields to reflect changes in monthly average temperature and precipitation under each scenario, as well as increased carbon dioxide concentration in the atmosphere. The cost per acre of producing crops for a given rotation in a specific region was held constant across climate scenarios. However, the model allows for market-mediated price changes that arise from regional shifts in crops and practices and the aggregate use of inputs change as a consequence of changes in acreage. While interactions between the crop and livestock sectors are included in the analysis, the reported results are confined to crop production. The limitations of the model and climate data precluded analysis of yield impacts from the potential changes due to extreme weather events.
These climate scenarios were used with a crop-growth model to estimate the effect of changing weather patterns on crop yields and on a suite of environmental indicators associated with regional production methods. A regional agricultural sector model uses the simulated crop yields under each climate scenario to estimate how production, market, and environmental outcomes differ from a baseline that assumes no climate change. The study examines both the impacts that adapting to climate change could have on agricultural returns and the possible further impacts of temperature-induced shifts in crop pest pressure. The study simulates adaptation by allowing farmers to shift crop acreage, crop rotations, and tillage practices in response to changing yield and market patterns. It also includes an analysis of the potential benefits from introducing drought-tolerant crops in water-stressed regions.
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