Arctic Ocean invaded by hot, salty water

Sea surface temperatures on the Northern Hemisphere have been rising dramatically over the years, as illustrated by above image, indicating that the latent heat tipping point is getting crossed, while the methane hydrates tipping point could get crossed soon, depending on developments.

[ click on images to enlarge ]

The image on the right, from the NSIDC article A step in our Spring, compares sea ice age between March 12 to 18 for the years 1985 (a) and 2021 (b).

The bottom graph (c) shows a time series from 1985 to 2021 of percent ice coverage of the Arctic Ocean domain. The Arctic Ocean domain is depicted in the inset map with purple shading.

At the end of the ice growth season in mid-March, 73.3% of the Arctic Ocean domain was covered by first-year ice, while 3.5% was covered by ice 4+ years old. 

In March 1985, near the beginning of the ice age record, the Arctic Ocean region was comprised of nearly equal amounts of first-year ice (39.3%) and 4+ year-old ice (30.6%).

As the animation underneath on the right shows, freshwater is entering the Arctic Ocean due to runoff from land, i.e. rainwater from rivers, meltwater from glaciers and groundwater runoff from thawing permafrost. 

The image below further illustrate the danger. As the temperature of the water keeps rising, more heat will reach sediments at the seafloor of the Arctic Ocean that contain vast amounts of methane, as discussed at this page and in this post.

Ominously, methane levels reached a peak of 2901 ppb at 469 mb on May 13, 2021. 

Research

In the extract of a 2008 paper, Natalia Shakhova et al. conclude: “. . we consider release of up to 50 Gt of predicted amount of hydrate storage as highly possible for abrupt release at any time.”

Natalia Shakhova: “The total amount of methane in the atmosphere is about 5Gt. The amount of carbon in the form of methane in this Arctic shelf is – approximately – from hundreds to thousands Gt and, of course, only 1% of [such an] amount is required to double the atmospheric burden of methane.”

“But to destabilize 1% of this carbon pool, I think, not much effort is needed, considering the state of the permafrost and the amount of methane involved, because what divides the methane from the atmosphere is a very shallow water column and the weakening permafrost, which is losing its ability to seal, to serve as a seal, and this is, I think, not a matter of thousands of years, it’s a matter of decades, at most hundred years.” 

(Natalia talks with Igor Semiletov)
Natalia Shakhova: “Just because this area is seismically and tectonically active, and there was some investigation that the tectonic activity was increasing, and the seismic activity, the destabiliation of the ground, just mechanical forcing destabiliation [may suffice to act as] additional pathway for this methane to escape. There are many factors that are very convincing for us [to conclude] that it might happen.”

Elaborating on the timeframe.
Natalia Shakhova: “Not any time, any time sounds like it might happen today, it might happen tomorrow, the day after tomorrow . . ” 
Igor Simelitov: “It might!”

The image below was created with content from a 2019 paper by Natalia Shakhova et al. It concludes that methane releases could potentially increase by 3-5 orders of magnitude, considering the sheer amount of methane preserved within the shallow East Siberian Arctic Shelf seabed deposits and the documented thawing rates of subsea permafrost reported recently.

In a 2021 paper by researchers from Europe, Russia and the U.S., results from field research are published showing that methane is getting released from locations deep below the submarine permafrost. Lead author, Julia Steinbach, from Stockholm University, says: “The permafrost is a closed lid over the seafloor that’s keeping everything in place. And now we have holes in this lid.”