Earth's permafrost likely to disappear by 2200 due to global warming: study

February 17, 2011 12:28 pm 

LOS ANGELES, Feb. 17 — About 30 to 60 percent of Earth's permafrost will disappear by 2200 as a result of warming temperatures, a new study warns.

While the permafrost is thawing, it will unleash vast quantities of carbon into the atmosphere, accelerating global warming in coming decades on the other hand, according to the study conducted by researchers at the University of Colorado Boulder's Cooperative Institute for Research in Environmental Sciences.

Using Intergovernmental Panel on Climate Change scenarios and land-surface models for the study, the researchers 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.

After taking into account all of the permanently frozen ground at high latitudes around the globe, the researchers estimate a release of roughly 190 billion tons of carbon, most of it in the next 100 years.

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 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 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."

"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 in the atmosphere and the figure is rising, according to the study.

The increase, equivalent to about 435 billion tons of carbon, resulted primarily from human activities like the burning of fossil fuels and deforestation, the study said.

Greater reductions in fossil fuel emissions to account for carbon released by the permafrost will be a daunting global challenge, Schaefer said.

"The problem is getting more and more difficult all the time," he said. "It is hard enough to reduce the emissions in any case, but now we have to reduce emissions even more. We think it is important to get that message out now."

While other studies have shown carbon has begun to leak out of permafrost in Alaska and Siberia, the study by Schaefer and his colleagues is the first to make actual estimates of future carbon release from permafrost, according to the American Association for the Advancement of Science (AAAS), which published the study results on its website Wednesday.

The consensus of the vast majority of climate scientists is that the buildup of CO2 and other greenhouse gases in Earth's atmosphere is the primary reason for increasingly warm temperatures on Earth, the AAAS said. (PNA/Xinhua)



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