Global methane emissions from agriculture and other sources have increased dramatically in recent years, threatening efforts to combat climate change, new research shows. A team of international scientists warns that atmospheric methane concentrations have jumped rapidly since 2007 after a period of relative stagnation in the early 2000s. “Unlike CO2, atmospheric methane concentrations are rising faster than at any time in the past two decades and, since 2014, are now approaching the most greenhouse-gas-intensive scenarios,” they write in the journal Environmental Research Letters on December 12. This is alarming since methane’s warming potential is about 28 times greater on a 100-year horizon than that of carbon dioxide, the most common greenhouse gas. „Keeping global warming below 2 °C is already a challenging target, with most of the attention placed primarily on CO2 emissions,” the paper reads. “Such a target will become increasingly difficult if reductions in methane emissions are not also addressed strongly and rapidly.“

According to the scientists, around 60% of all methane emissions globally are human-induced, while the rest stems from wetlands and other natural sources. The analysis suggests that agriculture is mainly to blame for the recent rapid rise in global methane concentrations - with smaller contributions from fossil fuel use and possibly wetlands. Livestock production and agriculture account for nearly two-thirds of human-induced methane emissions. Cattle emit methane through bodily functions and manure, while rice fields emit methane when being flooded. “The fossil fuel industry has received most of the attention in recent years. Agricultural emissions need similar scrutiny,” said Rob Jackson, chair of Stanford’s Earth System Science Department and co-author of the paper. Although methane is a more potent greenhouse gas than CO2, it also “presents the best opportunity to slow climate change quickly,” said Jackson because it is much more short-lived in the atmosphere than CO2. This means that actions taken to reduce emissions will show rapid results, the researchers said. One possible solution for agriculture is to change the way rice is cultivated by reducing the flooding of paddy fields. „Modification of rice agriculture practices (e.g., semi-inundated paddies, dry cultivation) is well tested and promising, assuming yield and quality of the staple food for more than 3 billion people can be guaranteed“, the authors write. Other strategies include promoting less meat-intensive diets and modifying ruminants’ diet to limit methane emissions from intestinal processes. Measures in other areas could be covering landfills to capture methane emissions. According to the study, such mitigation policies in the agriculture and waste sectors are key to reducing methane emissions in most of the high emitting regions. “We still need to cut carbon dioxide emissions, but cutting methane provides complementary benefits for climate, economies and human health,” Jackson added. (ab)