A cornfield, silo and barn complex is seen in Richland County, Ohio.

(Jeff Greenberg/UIG via Getty Images)

At a Glance

Summers in the Midwest became cooler and rainfall increased during the second half of the 20th century.With increased crop production, more moisture is pumped into the atmosphere, which helps to cool temperatures and increase rainfall.

Intensive agriculture practices that began in the second half of the 20th century changed summer weather in the Midwest, a study found.

According to the study published in 2017in Geophysical Research Letters, became cooler and rainfall increased in the second half of the 20th century. Researchers with the Massachusetts Instituteof Technology and Dartmouth University attribute the weather changes to a dramatic increasein the yield of crops like soybeansand corn.

The study notes that average summer temperatures dropped as much as0.9 degrees Fahrenheit and rainfall increased 15 percent during the second half of the century.

Elfatih Eltahir, a co-author of the paperand the Breene M. Kerr Professor of Hydrology and Climate at MIT,noted in a February press release that the effects are "."

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According to the study, plants "breathe" in the carbon dioxide needed for photosynthesis by opening tiny poresknown as stomata. Every timethe pores open,moisture is lost to the atmosphere.

Increased crop yields that resulted from denser plants with greater leaf mass added more moisture into the atmosphere, whichcooled temperatures and increased rainfall.

The annual yield of corn quadrupled between 1950 and 2009 and soybeans doubled, thanks to improved seeds, fertilizers and other practices.

Changes in average summertime temperatures are shown on this map, with higher than average temperatures in red, lower than average in blue. The analysis shows a very strong correlation between the areas with increased crop production, higher rainfall and lower temperatures.

(MIT)

"For some time, we’ve been interested in how changes in land use can influence climate," said Eltahir. "It’s an independent problem from carbon dioxide emissions."

The scientists saymodels used in the study showed "a small increase in precipitation, a drop in temperatureand an increase in atmospheric humidity." Climate records corroboratedtheir findings.

The researchers say the research may provide local geoengineering techniques that could helplessen the impacts of global warming on asmall-scale regional basis.

On the negative side, the cooling effect of the intensification during the second half of the 20th century might have "masked" the realeffects of global warming in previous decades.

Eltahir says the team does notexpect any further weather changesin the Midwest, noting thatthe intensification was a "20th-century phenomenon, and we don’t expect anything similar in the 21st century."

Roger Pielke Sr., a senior research scientist at CIRES, at the University of Colorado at Boulder, who was not involved in this work, called the study "excellent" and "really important."

"The leadership of the climate science community has not yet accepted that human land management is at least as important on regional and local climate as the addition of carbon dioxide and other greenhouse gases into the atmosphere by human activities," he said, adding that "Professor Eltahir has been one of the pioneers in the improvement of our knowledge on this scientifically and societally important issue."