May, 2016:

“We see an alarming development,” says senior researcher Cathrine Lund Myhre at the Norwegian Institute for Air Research (NILU).

Levels of methane increased sharply from 2013 to 2015 and are the highest ever measured.

Director of the Norwegian Environment Directorate, Ellen Hambro, said that the development gives reason for concern. “If the reason is release of methane from thawing permafrost and from the Arctic Ocean, then it is alarming. It will give climate change a self-reinforcing effect,” Hambro said.

The main sources of methane include boreal and tropical wetlands, rice paddies, emission from ruminant animals, biomass burning, and extraction and combustion of fossil fuels. Further, methane is the principal component of natural gas, and leaks from sources such as pipelines and offshore and onshore installations are a known source of atmospheric methane. The distribution between natural and anthropogenic sources is approximately 40/60 respectively. Of natural sources there is a large unknown potential methane source under the ocean floor, known as methane hydrates and seeps. Further, a large unknown amount of carbon is bound up in the permafrost layer in Siberia and North America, and this could be released as methane if the permafrost layer melts in response to climate change.

Reference: compiled from press release
http://www.thebarentsobserver.com/ecology/2016/03/scientists-beat-alarm-levels-methane-increasing-rapidly-arctic