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Massive Arctic Warming Can Still Be Averted by Rapid GHG Cuts, Carbon Brief Concludes

NASA/Wikimedia Commons

Climate analysts are taking a second look at a key paragraph in a widely-reported study, published last week by the UN Environment Program, that appears to have overstepped with the claim that Arctic warming between 5.0 and 9.0°C is locked in and inevitable by 2080.

The story “was covered by a number of news outlets, including The Guardian, Wired, The Hill, CBC, and others,” Carbon Brief reports. And on the whole, the report was solid news, documenting “a broad range of changes to the region’s climate, environment, wildlife and epidemiology.”

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But after taking a close look at the study, Carbon Brief “found that the section of the report on climate change erroneously conflates the Paris Agreement target—which is to limit warming to ‘well below’ 2.0°C by the end of the century relative to pre-industrial levels—with a scenario that has much more modest emission reductions which result in around 3.0°C of global warming,” the UK-based publication states.

The Arctic still warms faster than the rest of the world in an under-2.0° scenario. But if humanity can mobilize to hit that target, “future Arctic winter warming will be around 0.5 to 5.0°C by the 2080s compared to 1986-2005 levels, much lower than the 5.0 to 9.0°C values stated in the report,” Carbon Brief concludes. “This means that much of the future warming in the Arctic will depend on our emissions over the 21st century, rather than being ‘locked in’, as the report claims.”

The confusion centres on a single paragraph in a short, two-page section of the longer report that summarizes past technical studies but presents no new research, Carbon Brief notes. The net result is a major gap, laid out in detail in the Carbon Brief critique, between the findings in the original studies and the interpretation in the UNEP paragraph—which was later amplified in the agency’s media release for the study.

In a scenario where the Paris targets are met, multiple models project Arctic warming between 0.8 and 4.5°C from 1986 to the 2050s, and between 0.5 and 5.0°C into the 2080s—with a “multi-model mean” of 2.8°C on both time spans, and reduced emissions limiting further warming in the second half of the century.

“For once in my life, a tiny bit of good news to offer!” tweeted [2] 350.org co-founder Bill McKibben in response. “New analysis of the data says 5.0°C isn’t yet ‘locked in,’ and that if we cut emissions we can still cut it by some. So, let’s do! #climatestrike”

In The Guardian’s coverage [3] of the report release, UNEP Acting Executive Director Joyce Msuya pointed to the still-pressing concern that the Arctic could reach a “tipping point”, in which rapid permafrost melt leads to massive atmospheric methane releases that trigger runaway global warming.

“What happens in the Arctic does not stay in the Arctic,” she said. “We have the science. Now more urgent climate action is needed to steer away from tipping points that could be even worse for our planet than we first thought.”

The Guardian adds that “making drastic cuts to black carbon and short-lived pollutants such as methane could reduce warming by more than 0.5°C, according to previous research.”