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Is methane release from the Arctic unstoppable?

Global warming has already caused the Arctic to release more climate-warming methane—but exactly how much will depend closely on the actions we take to halt climate change.

 

September 25, 2024

Under the Arctic ice lies an extremely carbon-rich environment. Over thousands of years, plants in the Arctic have absorbed carbon dioxide (CO2) from the air to grow, before being buried under snow and ice during the winter, becoming part of the soil. If this perennially frozen ground thaws—as it is now, as a result of climate change—ancient plants are uncovered, alongside plant-eating microbes that break them down.

This releases two main climate-warming greenhouse gases: CO2, and even more potent methane. 

Seasonal thawing in the Arctic is normal. The region has very cold winters and warmer summers. Every year, the top, “active layer” of soil thaws and refreezes, exchanging methane and CO2 with the atmosphere. But today, those methane and CO2 emissions have greatly increased, as human-caused climate warming causes the active layer to grow deeper and deeper, digging into the “permafrost” below. The Arctic is warming four times faster than the world average,1 and as a direct result, methane emissions from the Boreal-Arctic region (which includes the Arctic as well as some areas a bit further south) have increased by 9 percent since 2002.2 Some areas have become an annual CO2 source, meaning more CO2 is released during the year than plants can absorb during the short summers.

The scale of these emissions is so large that they are likely to create a feedback loop, says Kyle Arndt, a research scientist focused on the Arctic at the Woodwell Climate Research Center. The extra greenhouse gases in the atmosphere will make the planet warm faster, which then causes more of the Arctic to thaw. 

But this feedback loop is not like an “on or off” switch, which, once flipped, will eventually release all the carbon buried in the Arctic. It’s more like a dimmer switch, where every fraction of a degree the planet warms causes more permafrost to thaw. And that means that everything we do to reduce warming—by choosing clean transportation and electricity, for instance, instead of those run on climate-warming fossil fuels—will keep more permafrost stable and frozen. “Any amount of reduced, human-caused emissions that we can do means reduced emissions from the Arctic,” says Arndt. 

Exactly how much methane release we can prevent is hard to say. Scientists understand very well how methane is released from the Arctic, but they are still working out how fast it may happen. Thawing into the permafrost “is on a one-way trajectory right now,” says Arndt. “We do expect to lose a good amount of the permafrost area by the end of the century due to warming.” 

Arndt says this thawing permafrost is often not accounted for in global climate models, which means climate plans based on these models may underestimate future warming. Scientists are also working to better understand a phenomenon called “abrupt thaw,” where permafrost thaws very quickly. That leads to landslides and ground collapse, as ice suddenly turns to water, releasing large amounts of methane suddenly. Arndt says scientists still can’t predict how much this will happen or exactly where. 

But we can be sure that, if we do nothing more to halt climate change, the Arctic will become a gigantic source of greenhouse gases over the next century, says Arndt. At current rates of warming, the region, which includes part of Russia, Greenland, Canada, Scandinavian countries, and Alaska, is on pace to contribute as much methane and CO2 to the atmosphere as a large, industrialized country.3 

And we also know what can help slow this trend. “Reducing human-caused emissions and warming will be the main way we can keep more permafrost frozen in the future,” says Arndt. 

 

Thank you to Michael Zeldich of New York City, New York, for the question.

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Footnotes

1 Chylek, Petr, et. al., "Annual Mean Arctic Amplification 1970-2020: Observed and Simulated by CMIP6 Climate Models." Geophysical Research Letters, Volume 49, Issue 13, 2022, doi:10.1029/2022GL099371.

2 Yuan, Kunxiaojia, et al., "Boreal–Arctic wetland methane emissions modulated by warming and vegetation activity." Nature Climate Change, Volume 14, 2024, doi:10.1038/s41558-024-01933-3.

3 Schuur, Edward, et al., "Permafrost and Climate Change: Carbon Cycle Feedbacks From the Warming Arctic." Annual Review of Environment and Resources, Volume 47, 2022, doi:10.1146/annurev-environ-012220-011847.