Surprise! Thawing permafrost will make the oceans acidic faster. And Subsea Siberian Shelf permafrost is already warmed up.
The researchers have been comparing the temperatures of permafrost on land and underwater. About 10,000 years ago, the temperature of both permafrost types was about -18˚C. They found that permafrost on the ground has now warmed up to about -10˚C but under the sea it has reached 0˚C. "That was surprising," Prof. Gustafsson said. "I had no idea that subsea permafrost was thawing so quickly."
They've also examined what happens when thawed permafrost from land reaches the sea. Some of the released carbon reacts with water to form carbonic acid ...The team's findings point to much higher levels of ocean acidification than that predicted by the Intergovernmental Panel on Climate Change (IPCC) in their report published in 2014, which largely considered the effect of anthropogenic carbon emissions.
"Acidification could be 100 times more severe," Prof. [Örjan] Gustafsson said. "Ocean acidification by permafrost carbon from land is a new mechanism we hadn't thought about much, and we didn't think it was so strong." [emphasis mine]