Environment & Energy

nitpicker

(7,153 posts) Tue Oct 27, 2020, 03:38 PM Oct 2020

'Sleeping giant' Arctic methane deposits starting to release, scientists find

https://www.theguardian.com/science/2020/oct/27/sleeping-giant-arctic-methane-deposits-starting-to-release-scientists-find

'Sleeping giant' Arctic methane deposits starting to release, scientists find

Jonathan Watts Global environment editor

Tue 27 Oct 2020 15.40 GMTLast modified on Tue 27 Oct 2020 16.11 GMT

Scientists have found evidence that frozen methane deposits in the Arctic Ocean – known as the “sleeping giants of the carbon cycle” – have started to be released over a large area of the continental slope off the East Siberian coast, the Guardian can reveal.

High levels of the potent greenhouse gas have been detected down to a depth of 350 metres in the Laptev Sea near Russia, prompting concern among researchers that a new climate feedback loop may have been triggered that could accelerate the pace of global heating.
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The international team onboard the Russian research ship R/V Akademik Keldysh said most of the bubbles were currently dissolving in the water but methane levels at the surface were four to eight times what would normally be expected and this was venting into the atmosphere.
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The scientists – who are part of a multi-year International Shelf Study Expedition – stressed their findings were preliminary. The scale of methane releases will not be confirmed until they return, analyse the data and have their studies published in a peer-reviewed journal.

But the discovery of potentially destabilised slope frozen methane raises concerns that a new tipping point has been reached that could increase the speed of global heating.
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The 60-member team on the Akademik Keldysh believe they are the first to observationally confirm the methane release is already under way across a wide area of the slope about 600km offshore. At six monitoring points over a slope area 150km in length and 10km wide, they saw clouds of bubbles released from sediment.

At one location on the Laptev Sea slope at a depth of about 300 metres they found methane concentrations of up to 1,600 nanomoles per litre, which is 400 times higher than would be expected if the sea and the atmosphere were in equilibrium.
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The most likely cause of the instability is an intrusion of warm Atlantic currents into the east Arctic. This “Atlantification” is driven by human-induced climate disruption.
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