According to the most advanced study yet of the economic consequences of a melting Arctic the release of methane and carbon dioxide from thawing permafrost will accelerate global warming and add up to US$70 trillion to the world’s climate costs.
The paper, published in Nature Communications, said if countries fail to improve on their United Nations sponsored Paris Agreement commitments, this feedback mechanism, combined with a loss of heat-deflecting white ice, will cause a near five per cent amplification of global warming and its associated costs.
The authors said their study was the first to calculate the economic impact of permafrost melt and reduced albedo, a measure of how much light that hits a surface is reflected without being absorbed, based on the most advanced computer models of what is likely to happen in the Arctic as temperatures rise.
It shows how destabilised natural systems will worsen the problem caused by man-made emissions, making it more difficult and expensive to solve.
They assessed known stocks of frozen organic matter in the ground up to three metres deep at multiple points across the Arctic.
These were run through the world’s most advanced simulation software in the United States and at the United Kingdom’s Met Office to predict how much gas will be released at different levels of warming.
Even with supercomputers, the number crunching took weeks because the vast geography and complex climate interactions of the Arctic throw up multiple variables.
The researchers then applied previous economic impact models to assess the likely costs.
Permafrost melt is the main concern.
Greenhouse gases, which are released when organic matter that had been frozen below the soil for centuries thaws and rots, have already begun to escape at the current level of one degree Celsius of global warming.
So far the impact is small, and just 10 gigatonnes of carbon have been released from the permafrost.
However, this source of emissions will grow rapidly once temperatures rise beyond 1.5°C.
On the current trajectory of at least 3.0°C of warming by the end of the century, melting permafrost is expected to discharge up to 280 gigatonnes of carbon dioxide and three gigatonnes of methane, which has a climate effect that is 10 to 20 times stronger than CO2.
This would increase the global climate-driven impacts by $70tn between now and 2300.
This is 10 times higher than the projected benefits from a melting Arctic, such as easier navigation for ships and access to minerals, said the paper.
“It’s disheartening that we have this in front of us,” Dr Dmitry Yumashev of Lancaster University, told The Guardian newspaper.
“Even at 1.5°C to 2.0°C, 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.”
“We still have a time bomb, but it may not be as large as previously believed,” said Dr Yumashev.
However, he warned against complacency because even at the low end the damages are huge, the study has a considerable degree of uncertainty and the costs of several other potential tipping points have yet to be calculated.
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