The Good and Bad Climate News from Permafrost Melt

Earth’s subterranean carbon blisters are starting to pop.

Carbon inside now-melting permafrost is oozing out, leaving scientists scrambling to figure out just how much of it is ending up in the atmosphere. Whether recent findings from research that attempted to help answer this question are good or bad climate news might depend on whether you see an Arctic river basin as half full of mud — or half empty.

Frozen soils known as permafrosts can be found across the planet, and they’re concentrated heavily in the Arctic, which has been warming since the 1980s at twice the global rate. Taken together, permafrosts contain more carbon than is already in the atmosphere. Their warming-induced breakdown is helping to fill the atmosphere with greenhouse gases. In a self-feeding cycle, that's fueling the very climatic changes that are causing permafrost to waste away.

A team of U.S. scientists led by Cory studied Arctic waterways and found that nearly half of the carbon that’s eroding from melting Arctic permafrost is flowing through rivers and lakes and ending up in the seas. Eventually, that sea-bound carbon is likely to be gobbled into aquatic food chains or to settle on ocean floors. The rest is being oxidized in waterways into carbon dioxide, floating into the skies instead of out to sea.

The good news from their analysis, the results of which were published last month in Science: About 45 percent of the soil carbon that’s eroding from permafrost and muddying Arctic waters was found to be remaining in the waterways.

The bad news? Looked at from another perspective, 55 percent of it is being oxidized into climate-changing carbon dioxide. The vast majority of that is caused by the effects of sunrays, which break apart chemical bonds that hold carbon molecules together, setting in motion reactions that can produce CO2.

The worrying news, no matter how you dice the de-icing permafrost findings? "There's so much carbon stored in northern permafrost soils that even if, say, 10 percent of that carbon is released through the processes we studied, it would still have a big impact," Cory said. She calculated that "conservative" scenario would raise atmospheric carbon dioxide levels by 75 to 80 parts per million — over and above the effects of continued fossil fuel burning and other causes. And that, she said, would lead to "a lot of warming." 

“As the Arctic continues to warm, and the permafrost thaw gets deeper, what happens then is you’re bringing out a different kind of carbon,” she said. “It has a different chemical signature.”