Researchers call for reducing methane from food production

An international group of researchers has suggested breeding rice to require less flooding, altering feed for livestock to lessen intestinal processes that create methane, promoting less meat-intensive diets and deploying more farm bio-digesters as possible solutions for reducing methane from food production.

In parallel papers, published Monday in the journals Earth System Science Data and Environmental Research Letters, the researchers report that emissions of methane have jumped dramatically in recent years and are approaching an internationally recognized worst-case scenario for greenhouse gas emissions, namely temperatures rise as much as six degrees Fahrenheit, or four degrees Celsius, thus speeding sea level rise and more extreme weather.

While most climate change mitigation efforts have focused on carbon dioxide, methane's warming potential is about 28 times greater on a 100-year horizon, and its lifespan in the atmosphere is much shorter. In other words, it can do major damage, but getting it under control could tip the climate change equation relatively rapidly.

"Methane presents the best opportunity to slow climate change quickly," said Rob Jackson, the papers' co-author and chair of Stanford University's Earth System Science Department. "Carbon dioxide has a longer reach, but methane strikes faster."

Unlike carbon dioxide, the bulk of methane emissions are human-driven. Chief among those, according to the analysis, are agricultural sources such as livestock, which emit methane through bodily functions and manure, and rice fields, which emit methane when flooded.

Natural sources of methane, which account for 40 percent of all methane emissions, are more uncertain than human-driven ones, which are responsible for 60 percent of all methane emissions globally. Examples include methane leaking out of natural faults and seeping on the ocean floor, and the potential for increased emissions as permafrost warms.

Despite an oil and gas production boom in the United States, the study's authors see rising fossil fuel emissions playing a secondary role compared to agriculture for the global methane increase. There is a lesson to learn, Jackson was quoted as saying by a news release from Stanford. "The fossil fuel industry has received most of the attention in recent years. Agricultural emissions need similar scrutiny."

Besides efforts proposed to curb emissions from agriculture, the researchers said opportunities in other areas include venting and flaring of methane in coal mines, detecting and removing natural gas leaks from oil and gas drilling operations and covering landfills to capture methane emissions.

"We still need to cut carbon dioxide emissions," Jackson said, "but cutting methane provides complementary benefits for climate, economies and human health." Endit