Maybe, like me, you’ve been aware that this layer of frozen soil is thawing, that it’s important in the global puzzle of climate change … and that’s about the extent of it.  

The great news for both of us is that my colleague James Temple just published two in-depth stories about permafrost. His reporting took him to the boreal forests of Alaska, where he helicoptered into the wilderness to learn more about how this material could affect our climate both now and in the future.

I’d recommend you give both of James’s stories a read. There’s this feature about efforts to tackle the intensifying fires that are threatening permafrost, as well as this look at how researchers are trying to understand the complicated tangle of potential climate effects. Here are three things I took away.

Permafrost is the frozen layer of soil that’s under about 15% of land around the Northern Hemisphere. While technically material needs to be frozen for only two consecutive years to count as permafrost, most of our current permafrost formed during the last ice age.

That means there’s organic material that’s been frozen, and essentially locked away, for thousands of years. But as global temperatures tick up and this layer thaws, microbes are able to break down that organic matter, releasing carbon dioxide and methane—powerful greenhouse gases that drive climate change. Those emissions form a feedback loop, accelerating warming further.

The steady rise in global temperatures has already shrunk the footprint of the Arctic permafrost by about 12% since 1850, and the pace has been picking up in the last 50 years.

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