Global warming spells trouble for U.S. farms, experts say

By Patricia McBroom, Public Affairs

Campus agricultural experts estimate that a five-degree temperature rise — projected to occur in the next 30-50 years — could result in $15 billion to $30 billion in annual damage to U.S. crops.

22 August 2001 | The impact of global warming on U.S. agriculture appears to be much larger and more negative than has been recognized, according to a new analysis by campus agricultural experts.

And the impact is unambiguously negative. There is little chance that a significant rise in global temperature could benefit U.S. agriculture, reported the Berkeley scientists at the annual meeting in Chicago of the American Agricultural Economic Association.

They estimate that a five-degree temperature rise —projected to occur in the next 30-50 years at current rates of carbon dioxide accumulation in the atmosphere — could result in $15 billion to $30 billion in annual damage to American crops.

“People have postulated a wide range of possible impacts on agriculture from global warming. Some even believe there might be benefits. But our results show we can expect damage, not benefits,” said Anthony Fisher, chair of the Department of Agricultural & Resource Economics.

Fisher said mistakes have been made because people did not factor in the cost of providing a water supply in areas of the country that depend on natural rainfall for growing crops. Some two-thirds of American counties, mainly in the eastern and midwestern parts of the country, do not have irrigation systems for agriculture.

Past projections also have been based on the value of agricultural land that is close to urban areas. That value goes up as people optimize choices during rising temperatures, said Fisher.

By analyzing agricultural values in non-irrigated, rural areas of the country, the Berkeley team reached quite different, more certain conclusions, about the damage from global warming, he said.

“Non-irrigated U.S. agriculture is unambiguously damaged under the CO2 doubling scenario, and the damages are quite large relative to other estimates,” the team concluded in a summary to the paper.

The paper was presented in Chicago by Berkeley doctoral student Wolfram Schlenker. It was co-authored by Michael Hanemann, professor of agricultural and resource economics.

The team is currently analyzing the impact of global warming on California agriculture.