According to an article by Bob Berwyn published in Inside Climate News, "the slowdown of a key ocean current could release methane that is frozen in layers of organic seabed sediments along some of the world’s coastlines, a new study shows." This could lead to "a spike in seabed methane emissions" which could accelerate climate change.
University of California, Santa Barbara climate scientist Syee Weldeab says, "It has happened before" during a prehistoric climate change cycle. "The global average temperature was about 1 to 2 degrees Celsius warmer than now, due to changes in the amount of sunlight reaching Earth. The new study’s analysis of trace elements in the shells of ancient ocean microorganisms shows that was enough to free some methane from its icy state, he said."