Feeling the heat -- from corn to cabernet

U.S. agriculture could begin feeling the heat of climate change during the next few decades.  Growing seasons in major wine regions could become too hot, new research suggests, and winter seasons in cornfields could become too warm to curb the spread of pests.

The warnings come from innovative modeling research led by climate scientist Noah Diffenbaugh at Stanford University presented at the annual meeting of the American Geophysical Union in San Francisco.

According to a 2006 study by Diffenbaugh and colleagues, projected sharp increases in the frequency of extremely hot days -- 95 degrees Fahrenheit or higher -- during the grape growing season could reduce the U.S. wine grape region by 81 percent by the end of the century.

"A key question now is how soon will that severe heat emerge," Diffenbaugh said.  "In our new near-term climate projections, we're finding that the hottest temperatures on record will become commonplace within the next 30 years."

In the case of U.S. corn production, the spread of common pests such as the corn earworm is effectively controlled by severe cold temperatures of winter.

"In our new simulations, we find that those temperatures could disappear over the next few decades, potentially leading to an expansion of pest pressure," he said.

The researchers developed new high-resolution regional climate impacts by introducing data on recent changes in a "suite of climate variables" critical to life cycle processes effecting crops and pests into the physics of large global climate models.

"It's the first time that a climate model has been applied at such spatial and temporal detail over such a long period of time," he said.  Diffenbaugh said these impacts will be felt in the next 30 years even if national governments succeed in their goal of holding global warming below 2 degrees Celsius -- 3.6 degrees Fahrenheit.