A previously unknown source of greenhouse gas has been found in Russia's Lena River and Kolyma River Deltas. Nitrous Oxide is the third most potent greenhouse gas behind carbon dioxide and methane. N2O was found to be seeping from eroding riverbanks in the Yedoma permafrost of eastern Siberia by Finnish researchers. Yedoma permafrost formed during the Pleistocene era, and it is up to 90% ice by volume. The carbon in the ice is organically rich. The Yedoma can be found in vast swaths of Alaska, the Yukon, and Siberia.
Nitrous oxide (N2O) is the third-most important greenhouse gas after carbon dioxide and methane and per unit mass an almost 300 times more potent warming agent than carbon dioxide. It is produced in soils due to microbial activity, per a presser from the University of Eastern Finland.
Nitrous oxide (N2O) is the third-most important greenhouse gas after carbon dioxide and methane, and per unit mass an almost 300 times stronger warming agent than carbon dioxide. It is produced in soils as a result of microbial activity. The discovery of nitrous oxide release from the late-Pleistocene-aged Yedoma permafrost is important due to the large area of the Yedoma region, and its large carbon and nitrogen stocks and high ice content, which makes it vulnerable for abrupt thaw. The nitrous oxide emissions from thawing permafrost represent a poorly known, but potentially globally significant positive feedback to climate change. Overall, the consequences of nitrogen release from permafrost for Arctic ecosystems have been insufficiently studied and remain poorly understood.
In the study published today, the researchers measured nitrous oxide emissions from the riverbanks of the East Siberian rivers Lena and Kolyma, where rapid permafrost thaw exposes Yedoma permafrost to the surface, releasing large amounts of carbon and nitrogen for microbial activity. The researchers found that nitrous oxide emissions from recently thawed Yedoma were initially very low but increased within less than a decade to high rates, exceeding typical emissions from permafrost-affected soils by one to two orders of magnitude (10–100 times). The increase in nitrous oxide emissions was related to drying and stabilization of the Yedoma sediments after thaw, and to associated changes in the microbial community participating in soil nitrogen cycle: the relative proportion of microbes producing nitrous oxide precursors (nitrate, nitric oxide) increased and the relative proportion of microbes consuming nitrous oxide decreased.
Usually, high nitrous oxide emissions occur from agricultural soils, where the availability of mineral nitrogen is high because of nitrogen fertilization and other management practices. Since the nitrogen cycling in cold Arctic soils is slow, they have previously been regarded as unimportant nitrous oxide sources. Based on accumulating evidence during the past years, however, this is not always true: nitrous oxide release has been found to be a common phenomenon in permafrost-affected soils, and the emissions increase with warming, disturbed vegetation cover and permafrost thaw.
The study abstract emphasized this point.
While freshly thawed, unvegetated Yedoma in disturbed areas emit little N2O, emissions increase within few years after stabilization, drying and revegetation with grasses to high rates (548 (133–6286) μg N m−2 day−1; median with (range)), exceeding by 1–2 orders of magnitude the typical rates from permafrost-affected soils.
It wasn't long ago that consensus on how quickly the Arctic is warming compared to the rest of earth was two times the planet's rate. Shortly after that, the agreement has been that warming is three times faster, but now that has increased to four times the global rate in some areas of the Arctic. The reason for these drastic rises in temperature is artic amplification, where the loss of sea ice has increased due to warming in the Arctic ocean from solar heat absorption. That loss of reflectivity increases dark surfaces of open water while causing the loss of snow and ice on land, darkening and heating permafrost instead of reflecting solar energy to space.
That frozen land is permafrost, and it has begun to thaw quickly, much faster than predicted. It has, along with many other feedbacks, ushered in the Arctic death spiral that scientists have warned about for decades that would happen without drastic efforts to discontinue our use of fossil fuels in favor of cleaner alternatives. This new finding on the Yedoma permafrost is worrying as the thawing process is much higher than the permafrost soils in other areas of the Arctic.
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