Increased methane hinders fight against global warming

Methane emissions shot up in the previous decade, according to a new international study, which will hurt the fight against global warming.

According to the study released by the Global Carbon Project, methane levels rose slowly from 2000 to 2006, then jumped ten times as fast in the following decade. There was an especially high jump in methane levels in 2014 and 2015. In that two-year period methane concentrations jumped by 10 or more parts per billion (ppb) annually, versus an average increase of 0.5ppb during the early 2000's.

"We should do more about methane emissions. If we want to stay below a 2 degrees Celsius temperature increase, we should not follow this track and need to make a rapid turnaround," said Marielle Saunois, lead author of the study and assistant professor at the Université de Versailles Saint-Quentin.

Methane is less prevalent in the atmosphere than carbon dioxide, the main greenhouse gas, but it captures 28 times more heat than carbon dioxide. Saunois said the reason why there has been a surge in methane was not known, but most likely sources are cattle ranching and rice farming. Cows expel methane and flooded soils of rice paddies create microbes that produce methane. Saunois said data from the United Nations' Food and Agriculture Organization showed livestock production expanded from roughly 1.3 billion cattle in 1994 to nearly 1.5 billion 20 years later, and there was a similar increase in rice production.

Robert Jackson, a co-author of the paper and professor in the Earth System Science at Stanford University said methane can come from many sources, including natural sources. Roughly 60 percent is thought to be rooted in human activities such as farming.

"When it comes to methane, there has been a lot of focus on the fossil fuel industry, but we need to look just as hard, if not harder, at agriculture," said Jackson.

kbd/msh (AFP, Reuters)