Melting ‘Permafrost’ Releases Climate-Warming CO2 Even Faster Than We Thought

We’ve known for a while that “permafrost” was a misnomer (see “Thawing permafrost feedback will turn Arctic from carbon sink to source in the 2020s” and links below). The defrosting permamelt will likely add 0.4°F – 1.5°F to total global warming by 2100. A new study, “Surface exposure to sunlight stimulates CO2 release from permafrost soil carbon in the Arctic” suggests the process may happen even faster than we thought.

As permafrost ice melts, the soil collapses and either creates an erosional hole in the tundra or a landslide such as this one. These features are called thermokarst failures. Exposure to “sunlight may act as an amplification factor in the conversion of frozen C [carbon] stores to C gases in the atmosphere.” Picture: George Kling.

University of Michigan News Service

Ancient carbon trapped in Arctic permafrost is extremely sensitive to sunlight and, if exposed to the surface when long-frozen soils melt and collapse, can release climate-warming carbon dioxide gas into the atmosphere much faster than previously thought.

University of Michigan ecologist and aquatic biogeochemist George Kling and his colleagues studied places in Arctic Alaska where permafrost is melting and is causing the overlying land surface to collapse, forming erosional holes and landslides and exposing long-buried soils to sunlight.

They found that sunlight increases bacterial conversion of exposed soil carbon into carbon dioxide gas by at least 40 percent compared to carbon that remains in the dark. The team, led by Rose Cory of the University of North Carolina, reported its findings in an article to be published online Feb. 11 in the Proceedings of the National Academy of Sciences.

“Until now, we didn’t really know how reactive this ancient permafrost carbon would be — whether it would be converted into heat-trapping gases quickly or not,” said Kling, a professor in the U-M Department of Ecology and Evolutionary Biology. EEB graduate student Jason Dobkowski is a co-author of the paper.

“What we can say now is that regardless of how fast the thawing of the Arctic permafrost occurs, the conversion of this soil carbon to carbon dioxide and its release into the atmosphere will be faster than we previously thought,” Kling said. “That means permafrost carbon is potentially a huge factor that will help determine how fast the Earth warms.”

Tremendous stores of organic carbon have been frozen in Arctic permafrost soils for thousands of years. If thawed and released as carbon dioxide gas, this vast carbon repository has the potential to double the amount of the heat-trapping greenhouse gas in the atmosphere on a timescale similar to humanity’s inputs of carbon dioxide due to the burning of fossil fuels.

That creates the potential for a positive feedback: As the Earth warms due to the human-caused release of heat-trapping gases into the atmosphere, frozen Arctic soils also warm, thaw and release more carbon dioxide. The added carbon dioxide accelerates Earth’s warming, which further accelerates the thawing of Arctic soils and the release of even more carbon dioxide.University of Michigan ecologist George Kling at a landslide thermokarst on a glacial headwall near Toolik

Recent climate change has increased soil temperatures in the Arctic and has thawed large areas of permafrost. Just how much permafrost will thaw in the future and how fast the carbon dioxide will be released is a topic of heated debate among climate scientists.

Already, the melting of ground ice is causing land-surface subsidence features called thermokarst failures. A thermokarst failure is generated when ice-rich, permanently frozen soils are warmed and thawed. As the ice melts, the soil collapses and either creates an erosional hole in the tundra or—if the slope is steep enough—a landslide.

Thermokarst failures change the trajectory of the debate on the role of the Arctic in global climate, according to Kling and his colleagues. The unanticipated outcome of the study reported in PNAS is that soil carbon will not be thawed and degraded directly in the soils. Instead, the carbon will be mixed up and exposed to sunlight as the land surface fails.

Sunlight—and especially ultraviolet radiation, the wavelengths that cause sunburn — can degrade the organic soil carbon directly to carbon dioxide gas, and sunlight can also alter the carbon to make it a better food for bacteria. When bacteria feed on this carbon, they respire it to carbon dioxide, much the same way that people respire carbon in food and exhale carbon dioxide as a byproduct.

“Whether UV light exposure will enhance or retard the conversion of newly exposed carbon from permafrost soils has been, until recently, anybody’s guess,” said University of North Carolina’s Cory, the study’s lead author. “In this research, we provide the first evidence that the respiration of previously frozen soil carbon will be amplified by reactions with sunlight and their effects on bacteria.”

“We know that in a warmer world there will be more of these thermokarst failures, and that will lead to more of this ancient frozen carbon being exposed to surface conditions,” Kling said. “While we can’t say how fast this Arctic carbon will feed back into the global carbon cycle and accelerate climate warming on Earth, the fact that it will be exposed to light means that it will happen faster than we previously thought.”

The researchers analyzed water from seven thermokarst failures near Toolik Lake, Alaska, as well as 27 other undisturbed sites nearby.

In addition to Cory, Kling and Dobkowski, Byron Crump of the University of Maryland was a co-author of the PNAS paper. The research was supported by several grants from the National Science Foundation.

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19 Responses to Melting ‘Permafrost’ Releases Climate-Warming CO2 Even Faster Than We Thought

  1. chlduvth70s says:

    Then, of course, there’s the methane.

  2. Solar Jim says:

    Lacking in description: “carbon dioxide gas.” Should be “carbonic acid gas.”

    Hope the organisms that maintain the earth’s oxygen supply enjoy living in a warmed, acidic environment courtesy of you know who.

    Humanity’s Tombstone:
    Impacts were worse “than previously thought” ad infinitum.

  3. Rabid Doomsayer says:

    Karst falls into water produces methane. Karst falls onto dry ground, dried out and produces CO2.

    But don’t we get a lot of water when the permafrost melts? And if it all stays in place but warms, it can be anoxic and still produce methane.

    Is planet B ready?

  4. Billy Snapp says:

    Uh, if you’re going to be pedantic, you should know that carbonic acid is not a gas. It’s a solution-only compound.

  5. Villabolo says:

    Has the Arctic meltdown and its increasing the warmth of Siberia (through albedo change) been taken into account?

  6. Joan Savage says:

    Wonder how this might affect the annual cycle in the Mauna Loa CO2 record.

    As the thermokarst collapses are increased by what is apparently UVB (sunburn generating) wavelengths, that pretty much means that a CO2 release in the Arctic is expected in summer, when the Northern Hemisphere otherwise has a seasonal down-tick in CO2 gas.

    How a pulse of summer Arctic CO2 might mix and move in the atmosphere is an interesting topic, and I hope someone with the necessary skills looks into it.

  7. David Goldstein says:

    I am shocked- SHOCKED I tell you! – that carbon emissions from permafrost thaw may have been incompletely understood and, as a result, underestimated. This, of course, speaks to the non-linearity and unprecedented pace at which human activities are forcing change and dis-equilibrium. I am not a scientist (though I did take a science course called ‘Earthquakes and Man’ with all the football players at Stanford!) but, am I correct in my perception that this ‘much faster than geologic time’ acceleration is the big Achille’s Heel in the modeling and projection of scientists? I remember about a year ago at another climate website (a good one), an article where the climate scientist author essentially said we don’t need to worry about methane destabilization in ESIS area for quite a while yet. I read his reasons- many of which harkened back to previous geologic periods – and remember thinking ‘yeah, but those periods may not be very useful precedents- this is happening on much more compressed time scales’. My 2 cents. And, by the way, have folks noticed that CO2 levels have recently been boosting about 2.5 ppm per year (up from about 2). Hmmmm….could this be because of permafrost carbon release? (at least partially?).

  8. Solar Jim says:

    American Heritage Dictionary of the English Language (1971), carbonic acid gas: carbon dioxide.

    Carbonic acid gas combined with water results in carbonic acid. H2O + CO2 = H2CO3.

    What this suggests is that “carbon dioxide” is a description of a formula rather than the substance of the matter.

  9. Merrelyn Emery says:

    Don’t empty that pseudo-shock piggy bank just yet as Earth continues to demonstrate she is a system and simply doing what systems do, ME

  10. Dick Smith says:

    Thanks for another informed, positive and thoughtful suggestion. It’s rare that you don’t add to my knowledge in some way. Thank you.

  11. Lou Grinzo says:

    I am not a scientist either, but my understanding is that this permafrost situation is just another example of how far ahead of the best efforts of scientists are our cumulative impacts on the environment.

    Once again, I urge people to think of the geography of the poles. The South is almost perfectly arrayed to result in a slow warming response (ice mostly on top of jagged land), as in our naive understanding of ice dynamics, etc. until fairly recently. The North is, by comparison, almost perfectly configured to result in very quick warming periods: An open ocean at the very top (allowing for a quick melt of ice and big albedo flip feedback) surrounded by land where 1.7 trillion tons of carbon can collect in permafrost, only to be liberated as CO2 and methane with “just a little warming”, aided in no small part by that albedo change.

    Are we at the point where that immense feedback is becoming a significant factor? I have no idea. But I sure hope it isn’t happening, because if it is, we are in vastly more trouble than almost anyone imagines.

  12. Artful Dodger says:

    Cory (2013) “Surface exposure to sunlight stimulates CO2 release from permafrost soil carbon in the Arctic”

    The full text of this Article is freely available online through the PNAS link above.

  13. Merrelyn Emery says:

    Let’s all hope Lou because I can’t imagine how we could possibly get that feral cat back in the bag, ME

  14. Mulga Mumblebrain says:

    ‘Impacts were worse…and still they did nothing’.

  15. Mulga Mumblebrain says:

    To paraphrase JBS Haldane, we are in more trouble than anyone CAN imagine.

  16. jyyh says:

    there’s no doubt this carbon might be of better use f.e. in biochar production, the most energy-intensive step in creating biochar-rich soils is of course the plowing in of the stuff. suggesting experimental fields to be created. this may be done by plowing at +50 cm (or as deep s possible some fields have only 10-15 cm of top soil) while dropping the stuff in the ground. test with plants with shallow root first to see how they do, then deeper-rooted plants. test the soil rigorously to see how pathogens and other bad stuff thrive in such a soil. maybe this is being done already somewhere. do this with increasing consentrations to find out what’s the maximum input allowable. compare yields with normal fields. find out how goof the chelation effect of biochar is with repect to nutrients.

  17. wili says:

    The main finding of the article is that permafrost seems to be more sensitive to sunlight than was thought.

    The albedo shift in the Arctic and sub-Arctic that is even more extreme than the loss of sea ice is the loss of snow cover.

    That enormous and dramatic shift means that more and more permafrost is exposed to more and more sunlight for more and more of the year.

    Apparently, all this new sunlight will drive permafrost melt even faster than what was previously thought.

    IIRC, one previous study predicted that permafrost would be a net source of, rather than sink for, atmospheric carbon by the 2020’s.

    So now should we move that date back to…basically … n o w ??

  18. wili says:

    Over the last few years, and especially in the last year, it has become ever clearer just what a large player terrestrial permafrost is and will become in the near and distant future of runaway global warming–CO2 levels, and so global temperatures, will now continue to rise into the indefinite future even if we could stop all further emissions immediately.

    For those interested in further reading, here are two excellent articles (out of many) from Skeptical Science on the issue:

    (See especially the graphs at figure 3.)

    I hope that it goes without saying that even after you realize that you have started an avalanche, it’s still a good idea to stop throwing pebbles, rocks and boulders down the mountainside.

    Oh, and our kids and grandkids (and really ourselves and all of complex life) are sitting at the bottom of the slope.

    As the graphs in the MacDougal article show, we may still be able to affect how fast we get to what level of GW.

    On top of that: while it is hard to see what could possibly stop this sea-ice-melt/permafrost-loss/climate-inferno landslide now that it has started, if there is some unknown unknown large ‘negative’ (dampening) feedback out there to save our sorry @$$e@, it would be prudent not to add forcings that would overwhelm whatever that feedback may be.

    (But then prudence is not exactly industrial civilization’s middle name.)

  19. Billy Snapp says:

    Carbonic acid is the hydrate of carbon dioxide, and is distinct. Carbon (C) dioxide (2 O) is how we come to CO2. Anyway, they’re both related. As atmospheric CO2 climbs, the amount of CO2 that dissolves into water (like the oceans) increases(chiefly in some form of carbonate or carbonic acid). That’s why the oceans are becoming increasing acidic.

    When the article states that carbon dioxide gas is released, it is inherently implied that this will affect all aspects of CO2’s cycle, including levels of H2CO3 in water (carbonic acid is STILL not a gas, though.) Also, the bacteria mentioned here(and humans) do not respire H2CO3; CO2 GAS is released.