Climate change impact on agriculture may be underestimated

March 11, 2016

Although researchers have previously found that increases in global temperatures would have harmful effects on global crop yields, this research has not taken into account how farmers may react to climate change, according to a study by researchers from Brown and Tufts Universities published in Nature Climate Change.

This study, which focused on an area in Brazil called Mato Grosso, found that if the patterns from 2002 to 2008 hold in the future, an increase in average temperature of just 1 degree Celsius will lead to a 9%–13% reduction in overall production of soy and corn. In addition, though, how farmers react to these changes will also impact production. For example, farmers might choose to put less land area into production because it is not profitable, or they might choose not to plant a second crop in a growing season—a common practice in Mato Grosso known as double cropping.

“Had we looked at yield alone, as most studies do, we would have missed the production losses associated with these other variables,” says Leah VanWey, professor of sociology at Brown and senior deputy director of the Institute at Brown for the Study of Environment and Society (IBES).

According to the results, temperature increases of 1 degree Celsius were associated with substantial decreases in both total crop area and double cropping, which accounted for 70% of the overall loss in production; only 30% was attributable to crop yield.

Taken together, the results suggest that traditional studies “may be underestimating the magnitude of the link between climate and agricultural production,” says Avery Cohn, assistant professor of environment and resource policy at Tufts, who led the work while he was a visiting researcher at Brown.

News release