One-third to two-thirds of Earth’s permafrost will disappear by 2200, unleashing vast quantities of carbon into the atmosphere, according to a study by the Cooperative Institute for Research in Environmental Sciences (CIRES), and the National Snow and Ice Data Center (NSIDC).
“The amount of carbon released 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.
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.
“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.
The carbon comes from plant material frozen in soil during the last ice age of the Pleistocene. The icy soil has trapped and preserved the biomass for more than 10,000 years.
Permafrost that took tens of thousands of years to form will melt in less than 200 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 the biomass will thaw and decay, releasing carbon into the atmosphere like any other decomposing plant material.
To predict how much carbon will enter the atmosphere, the thaw and decay of organic matter currently frozen in permafrost was modeled, under potential future warming conditions as predicted by the Intergovernmental Panel on Climate Change.
It was found that between 29 and 59 percent of the permafrost will disappear by 2200. That permafrost took tens of thousands of years to form, but will melt in less than 200.
It is estimated that an extra 190 gigatons plus or minus 64 gigatons of carbon will enter the atmosphere by 2200, which is about one-fifth the total amount of carbon currently in the atmosphere today.
Carbon emissions from thawing permafrost will require greater reductions in fossil fuel emissions, to limit the atmospheric carbon dioxide to some maximum value associated with a target climate.
The vicious exacerbating cycle of methane release and global warming .....
It is feared that Siberia's thawing lake region, which comprises 90 percent of the Russian permafrost zone, will release methane into the atmosphere at a rate that will overwhelm human actions to curtail carbon dioxide emissions.
As permafrost thaws as a result of global warming caused by more atmospheric carbon dioxide, large quantities of methane are released. This causes more warming in a vicious exacerbating cycle.
Permafrost then thaws at an even faster rate, dumping a greater volume of methane into the atmosphere. And so it carries on with global warming increasing exponentially. Scientists refer to this as a positive feedback loop.
Chris Field, director of global ecology at the Carnegie Institution of Washington, says "that's the thing that is scary about this whole thing. There are lots of mechanisms that tend to be self-perpetuating and relatively few that tend to shut it off."
Sergei Kirpotin of Tomsk State University describes permafrost melting as an "ecological landslide that is probably irreversible". He says the entire western Siberian sub-Arctic region began to melt in about 2002 or 2003.
Larry Smith of the University of California Los Angeles, has estimated that the western Siberian bog alone contains 70 billion tonnes of methane, which is 25 percent of all methane stored on the land surface worldwide.
When organic matter decomposes in air, the gas produced escapes as carbon dioxide. However much of the yedoma in Siberia lies at the bottom of thaw lakes, which produces methane when it decomposes under water.
The greenhouse gas methane, has a global warming potential 30 times greater than carbon dioxide over a 100-year period.
As methane (CH4), it has a shorter life of about a decade. Eventually it oxidizes to become carbon dioxide which then stays in the atmosphere for more than a hundred years.
Methane concentration in the atmosphere has increased from about 750 parts/billion (ppb) in the mid-18th century, to 1850 ppb in 2010.
Siberia is one of the fastest warming regions on Earth - average temperatures have increased 3°C during the last 40 years.
Siberian warming is believed to be a result of man-made climate change, a cyclical change in atmospheric circulation known as the Arctic oscillation, together with feedbacks caused by melting ice.
Exposure of darker bare ground and ocean absorb a greater amount of solar heat than white ice and snow.
Scientific findings on permafrost in Siberia are a strong reminder that it is evident that immediate, massive reductions in global warming gas emissions into the atmosphere are necessary to prevent runaway, irreversible climate change.
It has been known that feedbacks could exacerbate global warming, however, it was assumed that these changes would occur when warming was more advanced.
Permafrost thaw, polar ice reduction, and tropical rainforest drought are major climate change events that are occurring sooner, and at a greater pace than previously predicted. It is a strong indicator that the world is running out of time.
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