Climate variability has already affected rains, droughts and temperatures in several parts of the United States, said Cynthia Rosenzweig, a senior research scientist with NASA's Goddard Institute for Space Studies. "We are already seeing climate change."
"We are seeing the expansion of drying," said Rosenzweig, as she brought up a slide showing precipitation measurements across the United States. The measurements, comparing values from 1958 through 2008, showed significant reductions in rainfall across large portions of the Northwest and Southeast. Idaho, Washington, Montana, Georgia and Florida had some of the most drastic changes in rainfall on the map.
However, the opposite is not good either, she said, adding that increased soil moisture in some areas could potentially harbor insects and other pests. And, in general, "crops do not like to have their feet wet."
Aside from concerns about rainfall, local temperature is also extremely important for crop performance.
The reproductive development in many important grains is a process sensitive to temperature, said Paul Gepts, a professor of agronomy at the University of California, Davis.
Some plants need cold winters
One of the potential side effects of climate change is a trend toward milder winters in some regions. Vital plants, Gepts said, require a cold winter in order to properly develop their seeds for the next season.
Rosenzweig agreed. Heat waves, at odd times of the year, affect the proper development of proteins within corn kernels, she said. "It is like scrambling eggs."
Gepts also presented a number of well-known strategies for mitigating some of the possible economic effects of climate change on agriculture. Aside from breeding plants to be more drought-, heat- and pest-resistant, he also suggested varying the types of crops maintained on a particular site on the basis of environmental suitability.