Thawing Permafrost Likely Will Accelerate Global Warming
Permafrost and the melting of such under global warming has been of increasing interest to the scientific community. The latest research in this area at CIRES, as summarized by this U. of Colorado press release:
Up to two-thirds of Earth’s permafrost likely will disappear by 2200 as a result of warming temperatures, unleashing vast quantities of carbon into the atmosphere, says a new study by the University of Colorado Boulder’s Cooperative Institute for Research in Environmental Sciences.
The carbon resides in permanently frozen ground that is beginning to thaw in high latitudes from warming temperatures, which will impact not only the climate but also international strategies to reduce fossil fuel emissions, said CU-Boulder’s Kevin Schaefer, lead study author. “If we want to hit a target carbon dioxide concentration, then we have to reduce fossil fuel emissions that much lower than previously thought to account for this additional carbon from the permafrost,” he said. “Otherwise we will end up with a warmer Earth than we want.”
The escaping carbon comes from plant material, primarily roots trapped and frozen in soil during the last glacial period that ended roughly 12,000 years ago, he said. Schaefer, a research associate at CU-Boulder’s National Snow and Ice Data Center, an arm of CIRES, likened the mechanism to storing broccoli in a home freezer. “As long as it stays frozen, it stays stable for many years,” he said. “But if you take it out of the freezer it will thaw out and decay.”
A brief video discussing this issue by the lead researcher:
As he states, in order to figure out how much permafrost will melt they used a range of possible global warming scenarios, to take into account different possible amounts of warming (which depends upon human activity as well as random or pseudo-periodic natural phenonmena).
Schaefer and his team ran multiple Arctic simulations assuming different rates of temperature increases to forecast how much carbon may be released globally from permafrost in the next two centuries. They estimate a release of roughly 190 billion tons of carbon, most of it in the next 100 years. The team used Intergovernmental Panel on Climate Change scenarios and land-surface models for the study.
“The amount we expect to be released by permafrost is equivalent to half of the amount of carbon released since the dawn of the Industrial Age,” said Schaefer. The amount of carbon predicted for release between now and 2200 is about one-fifth of the total amount of carbon in the atmosphere today, according to the study.
While there were about 280 parts per million of CO2 in Earth’s atmosphere prior to the Industrial Age beginning about 1820, there are more than 380 parts per million of carbon now [ed. - closer to 390 ppm as of Feb 2011] in the atmosphere and the figure is rising. The increase, equivalent to about 435 billion tons of carbon, resulted primarily from human activities like the burning of fossil fuels and deforestation.
Using data from all climate simulations, the team estimated that about 30 to 60 percent of Earth’s permafrost will disappear by 2200. The study took into account all of the permanently frozen ground at high latitudes around the globe.
On that last sentence - the press release is too general, as the authors in the actual published paper state in the abstract:
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. We use surface weather from three global climate models based on the moderate warming, A1B Intergovernmental Panel on Climate Change emissions scenario and the SiBCASA land surface model to estimate the strength and timing of the PCF and associated uncertainty. By 2200, we predict a 29–59% decrease in permafrost area and a 53–97 cm increase in active layer thickness. By 2200, the PCF strength in terms of cumulative permafrost carbon flux to the atmosphere is 190 ± 64 Gt C. This estimate may be low because it does not account for amplified surface warming due to the PCF itself and excludes some discontinuous permafrost regions where SiBCASA did not simulate permafrost. 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.
The interaction of the biosphere with the climate is one of the great challenges of climatology (and ecology) in coming to understand exactly what effects human activity, such as the emissions of CO2, will have on the future.
Besides this latest paper, in the last few months there have been several other scientific papers looking at issues of the permafrost. E.g.:
All of which help build an argument that human induced global warming will have effects that act as positive feedbacks, for centuries.
Besides adding even more carbon to the atmosphere, melting permafrost will also affect the lives of people living in the Arctic regions as water supplies change, roads and structures collapse, etc.
In the big picture, human caused changes to the climate and the biosphere are sizable and for the most part irreversible. The choices we make today will effect future society in some very detrimental ways.
For more information on the arctic and permafrost, here is the National Snow and Ice Data Center (where the featured research was conducted) page on permafrost: All About Frozen Ground.