Study Examines the Effect of Climate Change on U.S. Agriculture

A new research headed by Cornell University has revealed that Midwest agriculture is becoming more and more susceptible to climate change owing to the region’s dependence on the cultivation of 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, began to examine the effect of drastic weather on the U.S. agricultural productivity. Individual field crops in the United States constitute one-third of the country’s agricultural output. Although earlier studies have looked at the susceptibility of these field crops, scientists have not dealt with the entire scope of agricultural production, which also includes livestock, at the national level.

We’re trying to get a big picture idea of what is going on. 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.

Ariel Ortiz-Bobea, Assistant Professor, CoBank/Farm Credit East Sesquicentennial Faculty Fellow in Production Economics and Sustainability, Cornell University

The ensuing paper titled “Growing Climatic Sensitivity of U.S. Agriculture Linked to Technological Change and Regional Specialization” has been published in Science Advances. The study identified particular areas in the United States that are becoming increasingly sensitive to drastic climate shocks. Midwest is the area of greatest concern. Here, soybeans, corn, and other rain-fed field crops have become progressively susceptible to warmer summers.

In order to obtain this panoramic picture, Ortiz-Bobea and his group utilized state-level measures of agricultural productivity that capture the way inputs, like feed, seeds, herbicides, fertilizer, and equipment are changed into economic outputs. The scientists mapped that data against almost 50 years’ worth of climate data between 1960 and 2004, fundamentally observing what exactly would transpire if weather was treated as an extra input.

The outcomes demonstrated an apparent increase in climate sensitivity in the Midwest region between two distinct time periods. In the 1960s and 1970s, there was an 11% reduction in productivity following a 2 °C rise in temperature during the summer months. However, after 1983, the same rise in temperature resulted in a 29% drop in productivity.

Although such damaging summer conditions normally happen 6% of the time, the scientists indicate that an extra 1 °C rise in temperature would increase their frequency by more than four-fold to approximately one of every four years.

Losing almost half your profit every four years? That’s a big loss,” stated Ortiz-Bobea, a 2017–2018 social sciences, humanities, and arts fellow with the Atkinson Center for a Sustainable Future.

The Midwest’s agriculture industry is progressively specialized in crop production, like oilseed and non-irrigated cereal crops, and as a result, the region is becoming increasingly susceptible to extreme climate changes.

Specialization in crop production is a compounding factor,” stated Ortiz-Bobea, who partnered on the study with Robert G. Chambers of the University of Maryland, and Erwin Knippenberg, a Cornell doctoral student in the field of applied economics and management.

Most of the agriculture in the Midwest is corn and soybeans. And that’s even more true today than it was 40 years ago. That has implications for the resilience to climate of that region, because they’re basically putting all their eggs in one basket, and that basket is getting more sensitive.

Ariel Ortiz-Bobea, Assistant Professor, CoBank/Farm Credit East Sesquicentennial Faculty Fellow in Production Economics and Sustainability, Cornell University

In the meantime, growers in the southwest, west, and southern plains are able to handle the extreme climate shocks because of their rigorous use of irrigation. Such regions are also dependent on the production of livestock and have come up with effective techniques like sprinkler systems and fans to help cows to cope with heat stress. In fact, it is easier to care for cows than for crops.

If you’re in the Midwest and it doesn’t rain and you don’t have irrigation, you’re in trouble, right?” Ortiz-Bobea stated. “There’s nothing you can really do about that in the middle of a drought.”

One major limitation noted by Ortiz-Bobea was that his group was unable to capture the impact of extended periods of multiyear droughts, thus potentially understating the exact long-term sensitivity of animal production and irrigated agriculture.

The advantage of having this type of aggregated data is that it summarizes so much information, but obviously we may be losing many nuances,” he stated, adding that such a wider view has correspondingly huge implications for policymakers. “You want regions that are more productive in a particular activity to specialize in those activities, but that could make the overall system more risky. So you have to think about risk-sharing across different regions in the U.S.”

Apart from studying present and past effects of climate variations on agriculture, Ortiz-Bobea is also looking ahead to the future.

Along with Jesse Tack of Kansas State University, Ortiz-Bobea authored a separate paper that was recently published in Environmental Research Letters. The study looks at the increased maize yields in the United States, ensuing from the extensive adoption of genetically engineered seeds starting in the 1990s and queries whether another revolution like this will be required to compensate the estimated yield losses under climate change. The brief answer is yes.

If these things materialize like the climate models are saying, you would need to have a sustained growth in yields that will need to exceed the historical rates we’ve seen over the past several decades. Otherwise you would have to increase more inputs – more fertilizer, more land – in order to have the supply to meet the demand of our rising population. Because the changes are coming – changes in temperature, changes in precipitation, and at a different magnitude than what we’ve seen.

Ariel Ortiz-Bobea, Assistant Professor, CoBank/Farm Credit East Sesquicentennial Faculty Fellow in Production Economics and Sustainability, Cornell University

Both studies were partially supported by the Atkinson Center for a Sustainable Future via its Faculty Fellowship for the Social Sciences, Humanities, and the Arts program.

Ariel Ortiz-Bobea, assistant professor of applied economics and management, discusses the impact of climate change on agricultural productivity in the United States. (Video credit: Cornell University)

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