Thawing arctic permafrost will release tons of methane and carbon dioxide into the atmosphere, worsening the man-made global warming that caused it and adding another AU$100 Trillion to the cost of climate change.

The authors of the study published in Nature Communications say it is the first to calculate the economic impacts of permafrost melt and sunlight that hits the northernmost reaches of the globe that will not longer be reflected back out into space because the snow cover is disappearing. They based their calculations on stocks of frozen organic matter that were pulled from the ground up to 3 meters deep at multiple points across the Arctic.

So far, with the average global temperature 1 C warmer than pre-industrial levels, 10 gigatonnes of carbon have been released.  This will get progressively worse as global warming rises to 1.5 degrees over pre-industrial levels, and then to 3 C degrees as expected by the end of the century if the nations of the world don't get their act together and honor their commitments to the Paris Climate deal.  By then, melting permafrost is expected to discharge up to 280 gigatonnes of carbon dioxide and 3 gigatonnes of methane, which has a climate effect that is 10 to 20 times stronger than CO2.

The additional AU$100 Trillion to the costs of global warming is roughly ten times higher than the economic benefits some feel they will reap from a warmer world, such as easier navigation for ships and access to minerals.

The lead author of the study Dr. Dmitry Yumashev of Lancaster University told National Geographic that melting permafrost and sea ice "are two known tipping elements in the climate system" that could trigger a cycle of unstoppable global warming - meaning that it will be too late if nations don't step up.

"It's disheartening that we have this in front of us," said Yumashev.  "Even at 1.5C to 2C, there are impacts and costs due to thawing permafrost.  But they are considerably lower for these scenarios compared to business as usual.  We have the technology and policy instruments to limit the warming but we are not moving fast enough."

Yumashev's co-author Kevin Schaefer of the National Snow and Ice Data Centre in Boulder, Colorado agrees.

"With climate change we're conducting a high-risk experiment where we don't know what is coming," Schaefer told National Geographic.  "The most important thing to remember about our study is the greater the warming, the stronger the feedbacks and the higher the costs to society."