Research Links Rice Agriculture to Global Warming

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NAU Professor Bruce Hungate is among a team of researchers who studied methane emissions from rice agriculture. Photo credit: International Rice Research Institute.

More carbon dioxide in the atmosphere and rising temperatures are causing rice agriculture to become a larger source of the potent greenhouse gas methane, new research published in Nature Climate Change reveals. This is important because rice is one of the world’s top three staple crops.

The researchers—Kees Jan van Groenigen, Research Fellow, School of Natural Sciences, Botany Department, Trinity College, Dublin, Ireland; Bruce Hungate, Professor of Biology, Northern Arizona University, and Chris van Kessel, Professor and Chair, Department of Plant Sciences, University of California-Davis—gathered published research from 63 different experiments on rice paddies, mostly from Asia and North America. They then used a statistical technique called meta-analysis to look for general patterns. “Two strong patterns emerged,” Hungate said. “First, more CO2 boosted emissions of methane from rice paddies; and second, higher temperatures caused a decline in rice yields.”

According to the study,  in the future the amount of methane emitted from rice paddies is likely to increase. “Together, higher CO2 concentrations and warmer temperatures predicted for the end of this century will about double the amount of methane emitted per kilogram of rice produced,“ said van Kessel. “Because global demand for rice will increase further with a growing world population, our results suggest that without additional measures, the total methane emissions from rice agriculture will strongly increase.”

The authors point out that there are options available to reduce methane emissions from rice agriculture—management practices such as mid-season drainage and using alternative fertilizers as well as switching to more heat-tolerant rice varieties and adjusting sowing dates. The study caught the attention of The New York Times, where it was featured in the paper’s green blog post.

--Adapted from "NAU News."