NSIDC bombshell: Thawing permafrost feedback will turn Arctic from carbon sink to source in the 2020s, releasing 100 billion tons of carbon by 2100
Study underestimates impacts with conservatives assumptions
February 17, 2011
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.
That’s the stunning conclusion from “Amount and timing of permafrost carbon release in response to climate warming” (subs. req’d), a major new study in Tellus by NOAA and the National Snow and Ice Data Center (NSIDC). As we’ll see, the figure above is almost certainly too conservative post-2080.
The permafrost permamelt contains a staggering “1.5 trillion tons of frozen carbon, about twice as much carbon as contained in the atmosphere, much of which 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 as potent over 20 years! One of the most conservative assumptions the study made, the lead author Dr. Kevin Schaefer confirmed in an email, is that all of the carbon would be released as CO2 and none as methane.
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. Heck, the NSIDC/NOAA study itself doesn’t even incorporate the CO2 released by the permafrost carbon feedback into its warming model!
Even so, in their study, the permafrost is adding more than one billion tons of carbon a year to the atmosphere by the mid-2030s!
Here’s some background on the permafrost and the study from the NSIDC release, “Thawing permafrost will accelerate global warming in decades to come, says new study”:
“The amount of carbon released [by 2200] is equivalent to half the amount of carbon that has been released into the atmosphere since the dawn of the industrial age,” said NSIDC scientist Kevin Schaefer. “That is a lot of carbon.”
The carbon from permanently frozen ground—known as permafrost —will make its impact, not only on the climate, but also on international strategies to reduce climate change Schaefer said. “If we want to hit a target carbon concentration, then we have to reduce fossil fuel emissions that much lower than previously calculated to account for this additional carbon from the permafrost,” Schaefer said. “Otherwise we will end up with a warmer Earth than we want.”
The carbon comes from plant material frozen in soil during the ice age of the Pleistocene: the icy soil trapped and preserved the biomass for thousands of years. Schaefer equates the mechanism to storing broccoli in the home freezer: “As long as it stays frozen, it stays stable for many years,” he said. “But you take it out of the freezer and it will thaw out and decay.”
Now, permafrost is thawing in a warming climate and—just like the broccoli—the biomass will thaw and decay, releasing carbon into the atmosphere like any other decomposing plant material, Schaefer said. To predict how much carbon will enter the atmosphere and when, Schaefer and coauthors modeled the thaw and decay of organic matter currently frozen in permafrost under potential future warming conditions as predicted by the Intergovernmental Panel on …