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Climate change accelerates

Carol Ryan Dumas
USDA is establishing regional climate hubs to help ag producers with accelerated climate change, which is causing erratic weather patterns and extreme events.The scientific community says warming temperatures are behind the changes that are challenging agriculture.

USDA has established regional climate hubs across the country to help farmers, ranchers and forest landowners adapt to a climate that is changing more quickly than it has in the past.

Coping with weather is nothing new to agriculture, but more severe storms, droughts, floods, and wildfires are occurring more frequently.

There have always been wet and dry periods and warm and cool periods, and agriculture has always been affected by those conditions, said Jerry Hatfield, an agricultural climatologist and director of USDA-ARS National Laboratory for Agriculture and the Environment in Ames, Iowa., one of USDA’s new climate hubs.

But temperatures are warming and becoming more variable from one extreme to the other, and precipitation patterns are becoming more erratic, Hatfield said.

“Temperature and precipitation are becoming pretty strange, and these changes affect agriculture in a big way,” he said.

For example, 2012 brought drought all over the country and all but one of the U.S. 50 states had snow this winter, he said.

A combination of things is causing an accelerated change in climate, with human influence beginning to exaggerate natural weather cycles, he said.

Cities, roads, deforestation all have an impact on the atmosphere. Increased water vapor content in the atmosphere, due to industry and more intensive crop production, and carbon dioxide emissions are also contributing factors, he said.

“Evidence for climate change abounds, from the top of the atmosphere to the depths of the ocean,” the National Climate Assessment and Development Advisory Committee stated in its latest draft climate assessment released last year.

Weather events have become more frequent and more intense, including heat waves, heavy downpours, floods and droughts. Sea level is rising, oceans are becoming more acidic, and glaciers and arctic sea ice are melting, the committee reported.

Observations of climate change in the U.S. include heat waves, river flooding and coastal flooding in the Northeast; decreased water availability and increased extreme events such as hurricanes in the Southeast; a longer growing season, heat waves, droughts and floods in the Midwest; drought and wildfires in the Southwest; and earlier snowmelt and reduced summer water supply in the Northwest.

The U.S. average temperature has increased 1.5 degrees Fahrenheit since 1895, with more than 80 percent of the increase occurring since 1980. And U.S. temperatures will continue to rise, the committee stated.

The next few decades are expected to see another 2 degrees to 4 degrees increase. Another 3 degrees to 10 degrees increase (depending on the level of greenhouse gas emissions) is expected by the end of the century, the committee reported.

Higher temperatures can cause direct and indirect problems, Hatfield said.

They can cause plants to bloom earlier, leaving them vulnerable to frost, and can cause a faster rate of crop development, resulting in lower yields and productivity, he said.

“Climate determines where we grow these plants, and it can get too warm,” he said.

Warmer temperatures can also increase the number and geographic range of insects, weeds and diseases that affect both crops and livestock. They can also contribute to dryness, growth of understory materials and insects that destroy trees, resulting in forest fires, he said.

“We need to be much more aware” of climate change affects to protect ag productivity, he said.

Regional agricultural systems are built on climate and weather patterns, and those are changing. For instance, the Midwest has built its system on summer rainfall, but that rainfall is becoming much more erratic. California built its system on capturing precipitation to supply irrigation water, but the state is in its third year of drought and reservoirs are empty, Hatfield said.

Despite much focus on climate change, producers’ biggest concern is always the weather within the growing season. Longer-term, they say they’ll slowly adapt, and they’ve always done that and increased productivity, he said.

Production will continue to adapt to climate change. The question is how to stabilize production with all the new variations in the growing season, he said.



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