Surge in methane emissions threatens efforts to curb global warming
Global concentrations of methane, a powerful greenhouse gas and cause of climate change, are now growing faster in the atmosphere than at any other time in the past two decades.
That is the message of a team of international scientists in an editorial to be published today in the journal Environmental Research Letters. The group reports that methane concentrations in the air began to surge around 2007 and grew precipitously in 2014 and 2015.
In that two-year period, concentrations shot up by 10 or more parts per billion annually. It’s a stark contrast from the early 2000s when methane concentrations crept up by just 0.5 parts per billion on average each year. The reason for the spike is unclear but may come from emissions from agricultural sources and mainly around the tropics – potentially from farm sites like rice paddies and cattle pastures.
Scientists involved in the editorial will discuss these trends at a session during the fall meeting of the American Geophysical Union (AGU) in San Francisco on Tuesday, December 13.
The findings could give new global attention to methane – which is much less prevalent in the atmosphere than carbon dioxide but is a more potent greenhouse gas, trapping 28 times more heat. And while research shows that the growth of carbon dioxide emissions has flattened out in recent years, methane emissions seem to be soaring.
“The leveling off we’ve seen in the last three years for carbon dioxide emissions is strikingly different from the recent rapid increase in methane,” says Robert Jackson, a co-author of the paper and a Professor in Earth System Science at Stanford University. The results for methane “are worrisome but provide an immediate opportunity for mitigation that complements efforts for carbon dioxide.” The authors of the new editorial previously helped to produce the 2016 Global Methane Budget. This report provided a comprehensive look at how methane flowed in and out of the atmosphere from 2000 to 2012 because of human activities and other sources.
Methane, Jackson says, is a difficult gas to track. In part, that’s because it can come from many different sources. Those include natural sources like marshes and other wetlands. But the bulk, or about 60 percent, of methane added to the atmosphere every year comes from human activities.