Airborne methane levels rose markedly last year, according to a preliminary estimate published today by the U.S. National Oceanic and Atmospheric Administration. The results show a dramatic leap in concentration of the second most-powerful greenhouse gas, which is emitted from both industrial and natural sources.

“Last year’s jump in methane is one of the biggest we’ve seen over the past twenty years,” said Rob Jackson, professor of Earth system science at Stanford University and chair of the Global Carbon Project. “It’s too early to say why, but increases from both agriculture and natural gas use are likely. Natural gas consumption surged more than two…