Not all climate-change mitigation involves changing human habits. In a paper in Nature on Wednesday, scientists unveiled a new genetically modified rice plant that reduces emissions of methane, a greenhouse gas 20 times more powerful than carbon dioxide. But the rice is at least 10 or 20 years from being available to farmers.
The new rice differs by only a single gene, borrowed from barley. The gene makes the rice produce less methane and yield 43 percent more grain per plant. “For three years of field trials it worked very well,” says Chuanxin Sun of the Swedish University of Agricultural Sciences, senior author on the paper. It was especially effective during the summer, he says, when it cut methane emissions to 0.3 percent to 10 percent of the control rice plants’ emissions. The new rice reduced emissions less dramatically in autumn, because of lower temperatures, but still cut methane emissions in half.
Sun’s team inserted a gene from barley into the rice to make it store more carbon—that is, starch and sugar—in its stems and grains, and less in its roots. But the scientists have yet to directly observe that changes in carbon storage are the reason for the lower methane. It seems plausible because rice paddies produce the greenhouse gas when their roots leak carbon into the soil, where microbes convert it into methane. With less carbon available to the microbes, they would, in theory, emit less methane. No one knows how else the new genetically modified rice would affect complex soil microbial communities.
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