Arctic melt `bubbling out` ancient methane

London -  Scientists have uncovered thousands of sites in the Arctic where methane that has been trapped for many millennia is seeping out into the atmosphere, which may adversely  impact climate change, according to a new study.

Methane is the second most important greenhouse gas after CO2 and ss one of the reasons behind global warming across the world.

There are several sources of the gas around the world, some natural and some man-made, like landfill waste disposal sites and farm animals.

Tracking methane to these various sources is not an easy task.

But the researchers on the new Arctic project, led by Katey Walter Anthony from the University of Alaska at Fairbanks (UAF), were able to identify long-stored gas by the ratio of different

isotopes of carbon in the methane molecules, the BBC reported.

The team used aerial and ground-based surveys and identified about 150,000 methane seeps in Alaska and Greenland in lakes along the margins of ice cover.

Local sampling divulged that some of these are releasing the ancient methane, perhaps from natural gas or coal deposits underneath the lakes.

On the other hand, others releases are much younger gas, most probably formed because of the decaying plant material in the lakes.

“We observed most of these cryosphere-cap seeps in lakes along the boundaries of permafrost thaw and in moraines and fjords of retreating glaciers,” the team wrote, emphasising the

point that warming in the Arctic is releasing this long-stored carbon.

"If this relationship holds true for other regions where sedimentary basins are at present capped by permafrost, glaciers and ice sheets, such as northern West Siberia, rich in natural gas

and partially underlain by thin permafrost predicted to degrade substantially by 2100, a very strong increase in methane carbon cycling will result, with potential implications for climate

warming feedbacks.”

The research revealed that the region stores vast quantities of the gas in different places.

These places include in and under permafrost on land, on and under the sea bed, and as showed by the latest research, in geological reservoirs as well.

"The Arctic is the fastest warming region on the planet, and has many methane sources that will increase as the temperature rises," said Euan Nisbet from Royal Holloway, University of

London, who is also involved in Arctic methane research.

"This is yet another serious concern: the warming will feed the warming," added Nisbet.

However the extent of seriousness and urgency that this feedback mechanism presents is a debatable topic.

Where, some scientists believe that the impacts will not be seen for many decades, others are pointing out the possibility of a rapid release that could swiftly speed up global warming.

The study has been published in the journal Nature Geoscience.