Warming Climate May Release Arctic's Massive Storehouse of Carbon from Frozen Soils

As temperatures warm amidst climate change, melting ice may release vast stores of carbon. Scientists have studied a massive storehouse of carbon in long-frozen Arctic soils and have found that it could represent a huge release of carbon into the atmosphere.

The Arctic contains a massive amount of carbon in the form of frozen soil, the remnants of plants and animals that died more than 20,000 years ago. Because this organic material was permanently frozen year-round, it didn't undergo decomposition like other materials. Instead, it was locked away from the bacteria that would have converted it to carbon dioxide.

"However, if you allow your food to defrost, eventually bacteria will eat away at it, causing it to decompose and release carbon dioxide," said Aron Stubbins, one of the researchers, in a news release. "The same thing happens to permafrost when it thaws."

Scientists conducted fieldwork in Siberia. There, a river carves into a ban of permafrost, exposing the frozen organic material. The researchers measured the carbon concentration, how old the carbon was and what forms of carbon were present in the water. Then, the scientists bottled it with a sample off the local microbes. After two weeks, they measured the changes in the carbon concentration and composition and the amount of carbon dioxide that had been produced.

"We found that decomposition converted 60 percent of the carbon in the thawed permafrost to carbon dioxide in two weeks," said Stubbins. "This shows the permafrost carbon is definitely in a form that can be used by the microbes."

The findings confirmed that the carbon in this thawing permafrost is at least 20,000 years old. This is significant because it means this carbon has not been a part of the global carbon cycle in the recent past. This, in turn, means that it could have a significant impact on our current climate.

"Currently, this is not a process that shows up in future (Intergovernmental Panel on Climate Change) climate predictions; in fact, permafrost is not even accounted for," said Robert Spencer, the lead author.

The researchers hope to find out how consistent their findings are and to better predict how fast this process will occur.

The findings are published in the journal Geophysical Research Letters.

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