Thawing Arctic Permafrost Could Release Billion Tons of Carbon in the Atmosphere
It has been widely speculated that the permafrost surrounding lakes in Alaska, Canada, Sweden and Siberia could potentially release billion tons of stored ancient carbon into the atmosphere, which could have a devastating effect in climate change.
"If you open the freezer door, you thaw permafrost soil that's been frozen for a long time, and the organic matter in it is decomposed by microbes," explained Katey Walter Anthony, a researche at University of Alaska Fairbanks and lead author of the study, in a statement.
Many scientists agree that a large permafrost carbon emission is imminent and previous study suggests that the release of ancient carbon has already begun. However, a new study showed nearly no signs of ancient carbon released. The study, published in the journal Nature Geoscience, also revealed that only a small amount of old carbon has been released in the past 60 years.
For the study, the researchers used radiocarbon dating to determine the age of methane emitted from the Arctic lakes that have recently grown to consume and thaw terrestrial permafrost.
Ancient carbon in stored in permafrost is released as carbon dioxide and methane when the frozen soil thaw and decompose. By radiocarbon dating the methane released from the permafrost, the researchers could determine the rate of the ancient carbon emissions in the soil alongside and beneath the lakes.
After analyzing 113 radiocarbon dating measurements and 289 soil organic carbon measurements, the researchers discovered that approximately 0.2 to 2.5 Pg of permafrost carbon was released as methane and carbon dioxide for the past 60 years.
When additional methane and carbon dioxide are released in the atmosphere, it could trigger a positive feedback loop. Carbon dioxide and methane are greenhouse gases that contribute to the warming temperature of the Earth. As the Earth's temperature increases, more permafrost will be thawed and additional carbon and dioxide and methane are released in the atmosphere, which could once again lead to warmer temperature that could accelerate the thawing of more permafrost.
Arctic permafrost is believed to store about billions of tons of ancient carbon, which is twice the amount of what is currently in our atmosphere.