During the Sangamon interglacial, rivers flowed north into the Arctic dumping organic material onto the shelves. At the start of the last glacial, ice dams formed, forcing the rivers to flow south. The sea level in the Arctic dropped exposing the shelves. The shelves remained exposed throughout the last glacial, and as the Holocene began, glacial meltwater turned the shelves first into a wetland, then with the rise of sea level, the shelves were submerged.
The permafrost that formed throughout the last glacial began to degrade even before the shelves were submerged as thermokarst lakes and rivers formed taliks. Much like is happening to terrestrial permafrost today.
Once submerged, the new warmer subsea environment, the salinity (think what happens when you put salt on a frozen doorstep), and geothermal flux from below, worked over the last 8,000 years to degrade the permafrost to the point that it now is pourous, and even totally gone in places, over an area of 2 million sq km.
Much of the methane hydrates that formed over the last 100,000 years since the Sangamon, dissociated, leaving a large reservoir of free methane gas under pressure, prevented from releasing only by the layer of permafrost which until now had acted as a cap.
Since the shelf is on average about 50 meters deep, any methane released does not interact with the water column, but releases directly to the atmosphere.
This is the end result of a geological process that has been going on for thousands of years and is a part of a natural cycle.
Over the last decade, the size of the areas releasing methane has increased and the amount being released has accelerated.
The release of just 1% of the available free methane on the shelf is enough to cause catastrophic warming.
Since there is no way to refreeze the degrading permafrost cap, the methane release is inevitable. There is no way to shut it off. And the methane will continue to release until there is no more left to release.
Whoever is questioning the decades of observations and research conducted by Semiletov and Shakhova haven't got a clue. Semiletov is the head of the far eastern branch of the Russian Academy of Sciences. Dozens of scientists have participated in this research.
If you have research papers providing rebuttal to their work, post it.
Just saying "some people say" doesn't cut it around here.
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