Sunday, February 27, 2011
Global warming is not going away, and over coming decades will worsen through the earth passing tipping points for carbon feedback mechanisms. One such tipping point is the thawing of arctic permafrost which will release huge amounts of carbon dioxide and further accelerate climate change. A new study has found that up to two thirds of permafrost is likely to disappear by 2200, much of it in the next 100 years, as a result of warming arctic temperatures resulting in the release of an estimated 190 gigatonnes of carbon into the atmosphere.
Anyone following the climate trend in the Arctic will be aware of the substantial temperature increases and warming that is occurring. The Arctic climate is warming at unprecedented rate due to Global Warming according to a 2010 NOAA report. There was Record summer melting in Greenland in 2010. Similar warming is occurring in northern Canada and Siberia.
The release of this carbon has implications for limiting global warming to the widely agreed two degree target. Human caused carbon emission targets will have to be that much greater to compensate for increasing emissions from thawing permafrost. Kevin Schaefer, lead author of the study from the National Snow and Ice Data Center at the University of Colorado, said "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 permafrost contains plant material, primarily roots trapped and frozen in soil during the last glacial period that ended roughly 12,000 years ago. While it is frozen, the carbon is trapped and stable.
The study was based on 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. The team estimated 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 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.
Greater reductions in fossil fuel emissions to account for carbon released by the permafrost will be a daunting global challenge, according to Schaefer. "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."
Indeed it is. Under the Copenhagen accord countries agreed "deep cuts in global emissions are required ... so as to hold the increase in global temperature below 2 degrees Celsius..." Yet analysis of the pledges set out in the Copenhagen accord shows the pledges are clearly inadequate to achieve a 2-degree goal, and instead imply a global emissions pathway leading to 3 to 3.9 degrees of warming. Current pledges would reduce global emissions between 4 percent and 16 percent below business as usual (BAU) in 2020. A 2-degree pathway requires reductions of 21 percent to 26 percent below BAU according to the Pew Centre on Global Climate Change. (Adding up the Numbers: Mitigation Pledges under the Copenhagen Accord (PDF)) For more information on pledges see climatetracker.org.
* Adapted from University of Colorodo media release, Feb 16, 2011 - Thawing permafrost likely will accelerate global warming in coming decades, says study