Climate Action Avoids over $300 Trillion in Damages at Super Low Cost - by Joe Romm

The present value of the damage caused by human-caused climate change from a moderate warming scenario is an astonishing $400 trillion, according to analysis from Cambridge University’s Judge business school.  The author, Chris Hope, an expert on the economics of climate change, told me that the “corresponding value for a low emissions scenario is about $80 trillion.”

We already knew the cost of climate action — the cost of achieving the lower emissions 2°C total warming scenario — was super-cheap without counting the benefit of the avoided climate damage.  Now it’s clear that the cost of inaction is simply staggering, even more so when you start to factor in key carbon-cycle feedbacks that pretty much every climate model ignores, like the thawing permafrost.

Hope is the lead author of a new Nature Climate Change study, which found “Under the A1B scenario, CO2 and CH4 released from permafrost increases the mean net present value of the impacts of climate change by US$43 trillion.”

A net present value of $43 trillion is an immense extra cost from the carbon dioxide and methane (CH4) released from the permafrost.  The A1B scenario is a good approximation of where the world will be headed after Paris — after you add up all of the commitments that the various nations of the world have made leading up to the big December climate talks.

Hope’s original analysis of the cost of inaction included, for example, estimates of the impacts of sea level rise, “agricultural losses and air-conditioning costs,” as well as costs associated with “human health and ecosystem impacts.”  The new analysis adds in the extra warming from the thawing of the permafrost, which contains 1.7 trillion tons of frozen carbon, almost twice as much carbon as contained in the atmosphere.

In its 2013 review of the scientific literature on permafrost, the U.N. Intergovernmental Panel on Climate Change (IPCC) found:

It is virtually certain that near-surface permafrost extent at high northern latitudes will be reduced as global mean surface temperature increases.  By the end of the 21st century, the area of permafrost near the surface (upper 3.5 m) is projected to decrease by between 37% (RCP2.6) to 81% (RCP8.5) for the model average.

The top 10 feet of permafrost are headed towards oblivion in the IPCC’s no-action case (RCP8.5) — but at least most of it appears to survive this century in the 2°C scenario (RCP2.6).  Given the huge amount of carbon in the permafrost, you might think the IPCC would factor in some of that carbon in their prognosis.  But they have always been super-cautious to a fault (see “IPCC’s Planned Obsolescence:  Fifth Assessment Report Will Ignore Crucial Permafrost Carbon Feedback”).

Back in 2011, a major study found that the carbon feedback from thawing permafrost will likely add 0.4°F to 1.5°F to total global warming by 2100.

The new study led by Hope looks at the impact of additional warming this century at the low end of that range, about 0.3°F.

Although one can’t directly compare Hope’s original analysis to this new one, Hope told me that avoiding the extra warming from the permafrost “would probably add about $40 trillion to the mean savings.”  That would mean aggressive climate action would avoid damages with a net present value of some $350 trillion.

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