Nature Bombshell: Climate Experts Warn Thawing Permafrost Could Cause 2.5 Times the Warming of Deforestation!
"Nature Bombshell: Climate Experts Warn Thawing Permafrost Could Cause 2.5 Times the Warming of Deforestation!"
Back in February, a major study found that thawing permafrost feedback will turn Arctic from carbon sink to source in the 2020s, releasing 100 billion tons of carbon by 2100. That study, by NOAA and the National Snow and Ice Data Center, conservatively assumed all of the carbon would be released as CO2 and none as the far more potent greenhouse gas, methane (CH4).
But that is unlikely, as this video of University of Alaska, Fairbanks, assistant professor Katey Walter Anthony, suggests:
A new article in Nature, “Climate change: High risk of permafrost thaw” (subs. req’d) concludes:
Arctic temperatures are rising fast, and permafrost is thawing…. Our collective estimate is that carbon will be released more quickly than models suggest, and at levels that are cause for serious concern.
We calculate that permafrost thaw will release the same order of magnitude of carbon as deforestation if current rates of deforestation continue. But because these emissions include significant quantities of methane, the overall effect on climate could be 2.5 times larger.
permafrost permamelt contains a staggering amount of carbon, which is starting to escape:
Recent years have brought reports from the far north of tundra fires1, the release of ancient carbon2, CH4 bubbling out of lakes3 and gigantic stores of frozen soil carbon4. The latest estimate is that some 18.8 million square kilometres of northern soils hold about 1,700 billion tonnes of organic carbon4 — the remains of plants and animals that have been accumulating in the soil over thousands of years. That is about four times more than all the carbon emitted by human activity in modern times and twice as much as is present in the atmosphere now.
As the article explains (see below), much of that carbon would be released as methane. Methane is 25 times as potent a heat-trapping gas as CO2 over a 100 year time horizon, but 72 times to 100 times as potent over 20 years!
The carbon is locked in a freezer in the part of the planet warming up the fastest (see “Tundra 4: Permafrost loss linked to Arctic sea ice loss“). Countless studies make clear that global warming will release vast quantities of GHGs into the atmosphere this decade. Yet, no climate model currently incorporates the amplifying feedback from methane released by a defrosting tundra.
The new analysis is based on a survey of “41 international scientists, listed as authors here, who publish on various aspects of permafrost.” Yet even this new paper is conservative. Their worst-case scenario appears to be derived from the out-of-date 2007 IPCC report, whereby Arctic warming “only” hits 7.5°C [13.5°F] by 2100. And the new article further assumes temperature is then held constant for the next 200 years.
More recent analyses make clear that business-as-usual warming — not worst-case — is likely to be considerably higher (see, for instance, “M.I.T. doubles its 2095 warming projection to 10°F — with 866 ppm and Arctic warming of 20°F“). And the Earth would continue warming well past 2100, perhaps 50% to 100% more.
Even so, the new analysis finds the permafrost releases up to 380 billion tonnes of CO2 equivalent by 2100. This is comparable to the NOAA/NSIDC finding for this century, which looks like this:
Carbon emission (in billions of tons of carbon a year) from thawing permafrost.
The main difference is the Nature article projects considerably higher Permafrost Carbon Flux (PCF) after 2100 — up to 865 billion tonnes CO2-eq by 2300.
The stunning conclusion of the NOAA/NSIDC paper was:
The thaw and release of carbon currently frozen in permafrost will increase atmospheric CO2 concentrations and amplify surface warming to initiate a positive permafrost carbon feedback (PCF) on climate…. [Our] estimate may be low because it does not account for amplified surface warming due to the PCF itself….
We predict that the PCF will change the arctic from a carbon sink to a source after the mid-2020s and is strong enough to cancel 42-88% of the total global land sink. The thaw and decay of permafrost carbon is irreversible and accounting for the PCF will require larger reductions in fossil fuel emissions to reach a target atmospheric CO2 concentration.
Again, that assumed all the PCF came out as CO2. The new study finds:
Across all the warming scenarios, we project that most of the released carbon will be in the form of CO2, with only about 2.7% in the form of CH4. However, because CH4 has a higher global-warming potential, almost half the effect of future permafrost-zone carbon emissions on climate forcing is likely to be from CH4. That is roughly consistent with the tens of billions of tonnes of CH4 thought to have come from oxygen-limited environments in northern ecosystems after the end of the last glacial period.10
And because of the much higher warming impact of methane over shorter time frames, even this low percentage level of methane means that over a 20 year period, the warming from CH4 will actually be higher than that of CO2.
The Nature article concludes:
Our group’s estimate for carbon release under the lowest warming scenario, although still quite sizeable, is about one-third of that predicted under the strongest warming scenario.
… our survey outlines the additional risk to society caused by thawing of the frozen north, and underscores the urgent need to reduce atmospheric emissions from fossil-fuel use and deforestation. This will help to keep permafrost carbon frozen in the ground.
For those who want more background on the permafrost, the news release is quite good. Here’s a final comment by the lead author:
“Even though we’re talking about a place that is very far away and seems to be out of our control, we actually have influence over what happens based on the overall trajectory of warming. If we followed a lower trajectory of warming based on controlling emissions from the burning of fossil fuels, it has the effect of slowing the whole process down and keeping a lot more carbon in the ground,” Schuur said. “Just by addressing the source of emissions that are from humans, we have this potential to just keep everything closer to its current state, frozen in permafrost, rather than going into the atmosphere.”
One last point. This article only looked at the land-based permafrost. Let’s remember the study from last year:
Science: Vast East Siberian Arctic Shelf methane stores destabilizing and venting: NSF issues world a wake-up call: “Release of even a fraction of the methane stored in the shelf could trigger abrupt climate warming.”Methane and carbon release from the Arctic is the most dangerous amplifying feedback in the entire carbon cycle. This research finds a key “lid” on “the large sub-sea permafrost carbon reservoir” near Eastern Siberia “is clearly perforated, and sedimentary CH4 [methane] is escaping to the atmosphere.”
Time‘s Bryan Walsh concludes his piece on the new article, “Scary stuff. But at least things are back to normal on the climate science beat: vaguely apocalyptic.”
The climate science is only apocalyptic if we keep ignoring it.
The people out there who think R&D or an energy quest is going to stop us from multiple catastrophes are deluding themselves and others. We need to start aggressive mitigation now as every major independent study concludes.
Related posts and amplifying feedbacks:
- Journal of Climate: New cloud feedback results “provide support for the high end of current estimates of global climate sensitivity”