Rice cultivation and draining peatlands to grow crops are causing significant greenhouse gas emissions, according to a study released this week by University of Minnesota researchers.
The study acknowledged the need to produce food for a growing population but questioned some practices, saying the resulting emissions per calorie of food produced were high.
Peatlands being drained anywhere from Indonesia to the midwestern United States are a good example, said Kimberly Carlson, now an assistant professor at the University of Hawai'i.
"Even though they produced less than one percent of global calories, they contributed about 32 percent of greenhouse gas emissions," Carlson said.
Minnesota is the state with the most peatlands in the contiguous U.S. Besides draining peatlands, the study found crop farming in the Midwest also contributes to greenhouse gas emissions through the application of nitrogen fertilizer.
"Those are quite concentrated, actually, in Minnesota and Iowa, the breadbasket of the United States," Carlson said.
The researchers concluded that peatland drainage and rice paddy cultivation account for about 80 percent of total global cropland greenhouse gas emissions. Rice cultivation emits methane, peatland drainage emits carbon dioxide and nitrogen fertilizer application emits nitrous oxide.
The study is published in the journal Nature Climate Change. The researchers said the study could help world leaders find ways to continue feeding the world while minimizing emissions linked to climate change.