Q. What effects would global climate change likely have
on U.S. agriculture?
A. Four recent analyses of projected
increases in global temperature
of 2.8 to 5.2°C (5.0 to 9.4°F) indicate that climate change
would either help or hinder U.S.
agricultural production by the end of the 21st century.
For example, production of wheat and nongrain crops would
likely increase relative to production under current climatic
conditions, while production of other grains, primarily
corn, would likely decrease. The direction of impacts
on aggregate crop production is indeterminate, ranging
from -0.7 to 3.8 percent.
Livestock production would likely decline, however, due to the
decreases in the production of corn, a major source of livestock
feed in the United States. Impacts on total agricultural production,
therefore, are lower than impacts on crops alone, ranging from -0.9
to 1.7 percent. These production changes coincide with changes in
consumer expenditures on goods and services, ranging from -0.08
to 0.03 percent (Darwin, 1999). This correspondence occurs because
agricultural commodities are used as inputs in the production of
many consumer goods and services. Income from U.S. agriculture,
however, increases in all four analyses, ranging from 1.8 to 4.6
percent. This is due to rising agricultural prices, ranging from
0.03 to 3.35 percent.
The shift away from corn and livestock production exemplifies the
adaptive capability of U.S. farmers. U.S. agricultural production
would likely suffer more without such adaptations (Darwin
et al., 1995; Schimmelpfennig
et al., 1996). This implies that, in order to effectively respond
to global climate change, U.S. farmers will require as much flexibility
in choosing their farming practices and crops as possible. U.S.
government activities (e.g., programs for crop insurance, disaster
assistance, and acreage reduction; tariffs and quotas; and agricultural
research) will affect the farm sector's response to climate change
by influencing both the economic incentives for farmers to adapt
and the technological options with which they can adapt (Lewandrowski
and Brazee, 1993). The 1996 Federal Agriculture Improvement and
Reform Act enhanced farmers' adaptive capabilities by removing many
restrictions so that farmers can adjust to changing conditions without
penalty.
These results are subject to a number of limitations.
- First, links in the chain from climate to water resources and
on to agricultural production are inadequately simulated. Water
storage in alpine snowpack, for example, is not taken into account.
Water is also treated as though it could be transported cost-free
anywhere within a given region. And water is implicitly assumed
to always be beneficial.
- Second, potential impacts on weather variability—both year-to-year
and short-term extreme events such as floods, storms, and dry
spells—are overlooked.
- Third, climate changes are applied to 1990 rather than projections
of future economic conditions.
- Fourth, the direct growth-promoting effects of greater atmospheric
concentrations of carbon dioxide on plants are not considered.
Research that overcomes shortcomings with regard to water resources,
weather variability, and future economic conditions is underway.
Research on the direct growth-promoting
effects of greater concentrations of atmospheric carbon
dioxide has recently been completed.
References
- Darwin, R.F. 1999. "A FARMer's View of the Ricardian Approach
to Measuring Effect of Climatic Change on Agriculture." Climatic
Change 41(3/4):371-411.
- Darwin, R.F., M. Tsigas, J. Lewandrowski, and A. Raneses. 1995.
World Agriculture
and Climate Change: Economic Adaptations. AER-703. U.S.
Dept. Agr., Econ. Res. Serv., Washington, DC.
- Lewandrowski, J.K. and R. J. Brazee. 1993. "Farm Programs and
Climate Change." Climatic Change 23(1):1-20.
- Schimmelpfennig, D., J. Lewandrowski, J. Reilly, M. Tsigas,
and I. Parry. 1996. Agricultural
Adaptation to Climate Change: Issues of Longrun Sustainability.
AER-740. U.S. Dept. Agr., Econ. Res. Serv., Washington, DC.
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