An international scientific team led by the University of Bristol had camped for three months near the Greenland Ice Layer, collecting samples from the meltwater flowing from a large (> 600 km2) basin of the Ice Layer during the summer of 2015. Publishing the study report in the journal Nature, the scientists state that they are using new sensors to measure methane (CH4) in the flow of molten water instantaneously, and observe that methane is continuously emerging from under the ice. The team calculates that at least 6 tons of methane is transported from this piece of Ice Layer to the measuring areas alone, adding that this is about the amount of methane released by 100 cows.
Leading the review, Prof. Jemma Wadham points out that one of their key findings is that most of the methane produced beneath the ice escaped from the Greenland Ice Layer in large, fast-flowing rivers, probably before they had time to oxidize to carbon dioxide. Methane is a greenhouse gas that is many times more effective than carbon dioxide, but normally it oxidizes until it reaches the atmosphere and turns into carbon dioxide (CO2). While carbon dioxide itself is enough to accelerate global warming, direct methane entering the atmosphere can have serious consequences.
Methane is now seen as the third most important greenhouse gas in the atmosphere, after water vapor and carbon dioxide; because its ratio in the atmosphere is not much. Most of the world’s methane is produced by microorganisms that convert organic matter to methane in the absence of oxygen. For example, plenty of methane is produced in the stomachs of cows and in the rice fields. The rest comes from fossil fuels such as natural gas.
While some methane was previously found in Greenland ice cores and an Antarctic Subglacial Lake, it was the first study to report that melted water formed in large ice sheet basins in spring and summer continuously releases methane from the ice sheet bed into the atmosphere. Lead author Guillaume Lamarche-Gagnon stresses that one of the striking results is that they have found clear evidence of a vast subglacial microbial system. Although methane-producing microbes are known to be important in subglacial environments, how important and widespread they actually are was debatable. We now know clearly that active microorganisms that live miles below the ice not only survive, but also affect other parts of the planet. It can be said that this subglacial methane is actually a biomarker of life in these isolated habitats.
Most of the research so far on arctic methane özgü focused on insoluble soils; because permafrost tended to hold large organic carbon stores and due to global warming they could be converted to methane when dissolved. The new study, on the other hand, revealed that ice layer deposits containing lots of carbon, liquid water, microorganisms and very little oxygen are also atmospheric sources of methane.
Source: https://bilimfili.com/atmosfere-ulasan-buz-katmani-metani-iklimi-etklemekbilir/
