Permafrost carbon leak could peak within a few decades: Study

Washington: Arctic permafrost’s expected gradual thawing due to climate change and the associated influx of greenhouse gases to the atmosphere may actually happen within a few decades, much earlier than previously thought, warns a new NASA-funded study.

For centuries, a massive store of carbon has been locked underground in the Arctic’s permanently frozen soil known as permafrost.

As Earth’s climate continues to warm and permafrost thaws, soil microbes in the permafrost can turn that carbon into the greenhouse gases carbon dioxide and methane, which then enter into the atmosphere and contribute to climate warming.

This release of greenhouse gases to the atmosphere may actually be sped up by instances of a relatively little known process called abrupt thawing, said the study published in the journal Nature Communications.

Abrupt thawing takes place under a certain type of Arctic lake, known as a thermokarst lake that forms as permafrost thaws.

“The mechanism of abrupt thaw and thermokarst lake formation matters a lot for the permafrost-carbon feedback this century,” said first author Katey Walter Anthony from University of Alaska Fairbanks in the US.

“We don’t have to wait 200 or 300 years to get these large releases of permafrost carbon. Within my lifetime, my children’s lifetime, it should be ramping up. It’s already happening but it’s not happening at a really fast rate right now, but within a few decades, it should peak,” Walter Anthony added.

Using a combination of computer models and field measurements, Walter Anthony and an international team of US and German researchers found that abrupt thawing more than doubles previous estimates of permafrost-derived greenhouse warming.

They found that the abrupt thaw process increases the release of ancient carbon stored in the soil 125 to 190 per cent compared to gradual thawing alone.

The research suggests that even in the scenario where humans reduced their global carbon emissions, large methane releases from abrupt thawing are still likely to occur.