Food securityMidwest at risk: Big-picture look at climate change impact on U.S. agriculture

Published 13 December 2018

A new study shows that Midwest agriculture is increasingly vulnerable to climate change because of the region’s reliance on growing rain-fed crops. The researchers set out to assess the impact extreme weather is having on agricultural productivity in the United States. While previous studies have looked at the vulnerability of individual field crops, which make up one-third of the country’s agricultural output, researchers haven’t addressed the whole scope of agricultural production, including livestock, at the national level.

A new Cornell-led study shows that Midwest agriculture is increasingly vulnerable to climate change because of the region’s reliance on growing rain-fed crops.

Ariel Ortiz-Bobea, assistant professor of applied economics and management and CoBank/Farm Credit East Sesquicentennial Faculty Fellow in Production Economics and Sustainability, set out to assess the impact extreme weather is having on agricultural productivity in the United States. While previous studies have looked at the vulnerability of individual field crops, which make up one-third of the country’s agricultural output, researchers haven’t addressed the whole scope of agricultural production, including livestock, at the national level.

“We’re trying to get a big picture idea of what is going on,” said Ortiz-Bobea. “The data captures every state’s agriculture over the past 50 years. If you see in the aggregate data that something big is happening, this really captures massive processes that are affecting many people at the same time.”

The resulting paper, “Growing Climatic Sensitivity of U.S. Agriculture Linked to Technological Change and Regional Specialization,” published in Science Advances, pinpoints the specific regions in the U.S. that are growing more sensitive to extreme climate shocks. The area of greatest concern is the Midwest, where rain-fed field crops like corn and soybeans have become increasingly vulnerable to warmer summers.

Cornell says that to get this panoramic snapshot, Ortiz-Bobea and his team used state-level measures of agricultural productivity that capture how inputs – such as seeds, feed, fertilizer, equipment and herbicides – are converted into economic outputs. The researchers mapped that information against nearly 50 years’ worth of climate data from 1960 through 2004, essentially seeing what would happen if weather was treated as an additional input.

The results show a clear escalation in climate sensitivity in the Midwest between two distinct time periods. In the 1960s and 1970s, a 2 degree Celsius rise in temperature during the summer resulted in an 11 percent drop in productivity. After the 1983, however, the same rise in temperature caused productivity to drop 29 percent.

While these damaging summer conditions usually only occur six percent of the time, the researchers indicate that an additional 1 degree C warming would more than quadruple their frequency to roughly one of every four years.

“Losing almost half your profit every four years? That’s a big loss,” said Ortiz-Bobea, a 2017-18 social sciences, humanities and arts fellow with the Atkinson Center for a Sustainable Future.