Exceeding 2 degrees Celsius

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President & Executive Director Philip B. Duffy

Permafrost is sometimes described as “permanently frozen soil.” If only it were! Unfortunately, climate change is causing arctic permafrost to thaw; you may have seen pictures of slumping buildings and trees where this has happened.  But the biggest danger from thawing permafrost is the release of greenhouse gases to the atmosphere.

Arctic permafrost, which covers 24% of northern hemisphere land area, is believed to contain much more carbon than the atmosphere, and more than tropical forests.  For this reason, release of carbon from thawing permafrost constitutes a major climate threat.

If thawing permafrost adds large amounts of carbon dioxide or methane to the atmosphere, it would greatly accelerate warming, which would lead to more thawing, etc.  This sort of thing has happened before. Fifty-six million years ago, a massive release of greenhouse gases raised the global temperature by at least 9°F in a warming episode that lasted 200,000 years.

We don’t want that to happen again, so understanding under what conditions it would happen is a critically important policy question.

A new paper co-authored by WHRC Assistant Scientist Susan Natali summarizes what is known about the fate of carbon stored in arctic permafrost.  Strangely, the findings in this paper have been described in relatively reassuring terms:

“Current evidence suggests a gradual and prolonged release of greenhouse gas emissions.”

“The permafrost carbon is not going to explode into the atmosphere catastrophically within just a few years.”

My reading of the paper is much less optimistic.  In order to keep global warming to less than 2°C (a widely cited goal), the Intergovernmental Panel on Climate Change says that we mustn’t emit more than an additional 300 or so billion tonnes of carbon.  That means 300 billion tonnes from all sources, all nations, and over all time between now and the end of the universe.  That sounds like a lot, but we’ve already emitted over 500 billion tonnes.

The new permafrost paper estimates that between now and 2100 nearly half of humanity’s 300+ billion tonne “allowance” will be emitted by thawing permafrost alone.  That means that the amount we can emit from fossil fuel use and land use change is only about half of what it otherwise would be, making it much more difficult to keep climate change under control.  And that assumes that all of the carbon released from permafrost will be in the form of carbon dioxide; if a significant amount comes out as methane, which we’re pretty sure it will, the situation is even worse.

The Center is at the heart of addressing this high-stakes challenge, both through the science we’re doing and through our engagement in arctic-related policy processes. We appreciate your interest and support of this critically important work.