Well, At Least One Catastrophic Climate Scenario Is Looking Less Likely

An aggregation of methane ice worms seen on a methane hydrate in the Gulf of Mexico. Image: NOAA
An aggregation of methane ice worms seen on a methane hydrate in the Gulf of Mexico. Image: NOAA

There’s been loads of media hype regarding the Arctic “methane bomb,” an idea that rising temperatures could cause a pulse of ancient methane, locked in permafrost and frozen hydrates on the ocean floor, to escape to the atmosphere, triggering catastrophic global warming. Well, we have some positive news for you: a new study finds little evidence to support this scenario playing out in at least one fast-warming part of the world.


The study, published this week in Science Advances, used a new radiocarbon analysis technique to parse out how much marine methane is from ancient sources versus more modern sources along a stretch of Alaska’s Beaufort Sea coastline. The authors found that ancient carbon—likely derived from methane hydrates and permafrost at the ocean floor—is indeed being released as methane into deep waters on this rapidly warming continental shelf. But those ancient sources don’t account for much of the methane near the surface, the stuff that could be making its way into the atmosphere.

The study didn’t directly investigate why, but the authors suspect seafloor methane could be getting broken down by ocean microbes before reaching surface waters, according to a press release.


“Our data suggest that even if increasing amounts of methane are released from degrading hydrates as climate change proceeds, catastrophic emission to the atmosphere is not an inherent outcome,” lead study author Katy Sparrow of the University of Rochester said in a statement.

It’s a single scientific study in a single part of the world, but it falls in line with a growing body of research on the fate of methane hydrates, which are widespread along continental margins, and are already suspected to be breaking down in the Arctic Ocean. A review paper published last year found “no conclusive proof that hydrate-derived methane is reaching the atmosphere now,” while suggesting “more observational data and improved numerical models” would help us better predict its future.

As a greenhouse gas, methane is roughly 80 times as potent as CO2 over a 20-year timespan, so we’d like to keep as much of it in the deep ocean as we can.

Róisín Commane, a carbon cycle scientist at Harvard University who was not involved with the study, told Earther via email that it “makes a lot of sense. It’s a nice study confirming that the whole ‘methane bomb’ argument isn’t valid.”


Commane added that she really liked the study’s final point that we need to learn more about how ocean microbes will adapt to rising temperatures to predict how additional thawing hydrates will affect the atmosphere.

Methane hydrates aside, there are other sources of methane that could add to our global warming woes. Land-based permafrost, which is slowly thawing all over the Arctic, could release a sustained pulse of methane as bacteria chew up all that carbon. Peat fires, poised to become more frequent in a warming world, are another potential source of large methane pulses.


Then, of course, there’s all the methane we humans emit, both through the oil and gas industry and through our burping, farting cows.

Maddie Stone is a freelancer based in Philadelphia.

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Doesn’t that leave the question of just how much methane those microbes can eat? If the oceans warm so that more methane is released, will all of it still be digested before reaching the atmosphere?