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Scientists have found evidence that frozen methane deposits in the Arctic Ocean – known as the “sleeping giants of the carbon cycle” – have begun to be released over a large area of the continental slope off the coast of eastern Siberia, may reveal the Guardian.
High levels of the potent greenhouse gas have been detected down to a depth of 350 meters in the Laptev Sea near Russia, sparking concern among researchers that a new climate feedback loop may have been triggered that could accelerate the pace of global warming.
The sediments of the slopes in the Arctic contain a huge amount of frozen methane and other gases, known as hydrates. Methane has a heating effect 80 times stronger than carbon dioxide in 20 years. The United States Geological Survey previously listed the destabilization of Arctic hydrates as one of the four most severe scenarios for sudden climate change.
The international team aboard the Russian research vessel R / V Akademik Keldysh said most of the bubbles were currently dissolving in the water, but the methane levels on the surface were four to eight times what would normally be expected. and this was taking place in the atmosphere.
“Right now, there is unlikely to be a major impact on global warming, but the point is that this process has been activated. This methane hydrate system on the slopes of Eastern Siberia has been disrupted and the process will be underway, ”Swedish scientist Örjan Gustafsson of Stockholm University said in a satellite call from the ship.
Why are methane hydrates considered “sleeping giants” for the climate?
Scientists estimate 1,400 gigatonnes of carbon are locked up in underwater hydrates (frozen methane and other gases) beneath the Arctic underwater permafrost, some of which may be vulnerable to global warming. If large volumes were released, this could quickly destabilize the climate because methane is a powerful greenhouse gas with a warming effect 80 times stronger than carbon dioxide over a period of 20 years.
Such concerns led the United States Geological Service to list the destabilization of Arctic hydrates as one of the four most serious scenarios for sudden climate change. This possibility – sometimes referred to as the “clathrate gun hypothesis” – has been the basis for apocalyptic scenarios of uncontrolled warming tilting the Earth towards a greenhouse state. However, several studies suggest such fears are exaggerated.
It looks scary. When could this happen?
There are many uncertainties: at what temperature the hydrates destabilize and, if they do, how quickly it will happen; and will the gas bubbles reach the surface and be released into the atmosphere or will they simply dissolve in the oceans? These and other questions are now the subject of intense research on the platform and slopes of the Laptev Sea and other areas of the Arctic.
The scientists, who are part of a multi-year expedition of international studies on the shelf, stressed that their results are preliminary. The extent of methane emissions will not be confirmed until their return, data analysis and publication of their studies in a peer-reviewed journal.
But the discovery of frozen methane on potentially destabilized slopes raises concerns that a new tipping point has been reached that could increase the rate of global warming.
The Arctic is considered ground zero in the debate on the vulnerability of frozen methane deposits in the ocean.
With the Arctic temperature now rising more than double the global average, the question of when – or even if – they will be released into the atmosphere has been a matter of considerable uncertainty in computer models of the climate.
The 60 members of the Akademik Keldysh team believe they are the first to confirm observationally that the release of methane is already underway over a large area of the slope about 600 km offshore.
At six monitoring points on a sloping area 150 km long and 10 km wide, they saw clouds of bubbles released from the sediments.
At a location on the side of the Laptev Sea at a depth of about 300 meters they found methane concentrations of up to 1,600 nanomoles per liter, which is 400 times higher than would be expected if the sea and the atmosphere were in equilibrium.
Igor Semiletov, of the Russian Academy of Sciences, who is the chief scientist on board, said the drains were “significantly larger” than anything found before. “The discovery of actively releasing platform slope hydrates is very important and unknown until now,” he said. “This is a new page. They can potentially have serious consequences on the climate, but we need more studies before we can confirm this. “
The most likely cause of the instability is an intrusion of warm Atlantic currents into the eastern Arctic. This “atlantification” is driven by human induced climate disruption.
The latest discovery potentially marks the third largest source of methane emissions from the region. Semiletov, who has studied this area for two decades, previously reported that gas is released from the Arctic shelf, the largest of any sea.
For the second consecutive year, his team has found crater-like pockmarks in the lower parts of the Laptev Sea and the East Siberian Sea that are discharging bubble jets of methane, which is reaching the sea surface at levels of tens to hundreds of times higher than normal. This is similar to the craters and sinkholes reported by the inland Siberian tundra earlier this fall.
Temperatures in Siberia were 5 ° C above average from January to June this year, an anomaly that was made at least 600 times more likely by man-made emissions of carbon dioxide and methane. Last winter’s sea ice melted unusually early. The frost of this winter has yet to begin, already a later start than any other recorded time.
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