“The East Siberian Arctic Shelf, a methane-rich area that encompasses more than 2 million square kilometers of seafloor…”

I guess my two cents may not be worth much, but methane is “frozen” in ocean floor sediments in a form that is known as a clathrate compound or clathrate hydrate. These compounds have been known for a long time, are very common, and exist in the shallow ocean sediments off the east coast of the United States, among many other places.

I suspect that the shallow ocean floor below the Atlantic ocean off of the east coast of the United States is much warmer than the East Siberian Arctic Shelf, and I would like to see how long they have been monitoring for methane. It’s possible that the methane has been “bubbling up” naturally for a long time (just like oil naturally seeps into the Gulf of Mexico), and they only found it when they when they went looking for it.