Greenland’s melting ice sheet bed releasing methane into atmosphere: Study

Greenland ice sheet emits tonnes of methane, according to a new study. It showed that the sub-glacial biological activity impacts the atmosphere far more than it was thought previously. The study, led by a team from United Kingdom's University of Bristol, found that ice sheet beds, which hold large reserves of carbon, liquid water, microorganisms and very little oxygen -- the ideal conditions for creating methane gas -- are also atmospheric methane sources. "What is also striking is the fact that we've found unequivocal evidence of a widespread sub-glacial microbial system. Whilst we knew that methane-producing microbes likely were important in sub-glacial environments, how important and widespread they truly were was debatable," explained lead researcher Guillaume Lamarche-Gagnon. 

ALSO READ | Scientists to start hunting for lives beneath Antarctic ice sheet

"Now we clearly see that active micro-organisms, living under kilometres of ice, are not only surviving, but likely impacting other parts of the Earth system. This sub-glacial methane is essentially a biomarker for life in these isolated habitats," Ms Lamarche-Gagnon added in the research paper reported in the journal Nature. 

Earlier, satellite data by the European Space Agency (ESA) showed that the pace at which Greenland is losing ice is getting faster. The research, published in the journal Earth and Planetary Science Letters, used radar altimetry data gathered by the European remote sensing satellite (ERS), Envisat and CryoSat missions between 1992 and 2016.

"A pattern of thinning appears to dominate a large fraction of the ice sheet margins at the beginning of the millennium, with individual outlet glaciers exhibiting large thinning rates," Louise Sandberg Sorensen, the lead author of the research paper had said.

"Over the full 25-year period, the general picture shows much larger volume losses are experienced in west, northwest and southeast basins of Greenland compared to the more steady-state situations in the colder far north," Sorensen had said.

ALSO READ | NASA spacecraft beams back first images of Ultima Thule

Methane gas (CH4) is the third most important greenhouse gas in the atmosphere after water vapour and carbon dioxide (CO2). Although, present in lower concentrations than CO2, methane is approximately 20-28 times more potent. 

The Greenland ice sheet is an important cog in the global climate system with its meltwater, for example, influencing ocean circulation in the North Atlantic, they said.