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Melting Permafrost Turns Arctic into Net Source of Greenhouse Gases

As scientists grow ever more certain that the Arctic is becoming a net contributor to climate change as its carbon- and methane-heavy permafrost melts, the 35 million people who call the polar region home fear exposure to heavy metals and dangerous pathogens, while witnessing a collapsing food chain.

In its latest annual Arctic Report Card, the U.S. National Oceanic and Atmospheric Administration (NOAA) reveals that a long-feared climate “tipping point [1]” may have been breached, such that “the Arctic itself may now be contributing to climate change,” writes [2] Vox. The report warns that “thawing permafrost throughout the Arctic could be releasing an estimated 300 to 600 million tons of net carbon per year to the atmosphere.”

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“That’s roughly the equivalent of Japan’s annual emissions,” adds Vox.

Using what Northern Arizona University permafrost expert and report co-author Ted Schuur described as “an unparalleled dataset” on permafrost emissions, the NOAA drew on numerous studies, including a NASA effort that “had planes fly over the Arctic for three years, measuring greenhouse gases over many Arctic ecosystems.” The result of that work, he said, “is a wake-up call.”

Though surface permafrost has been thawing for a number of years now, writes Vox, “the carbon it releases is usually taken up by plant life growing in the summer, so the Arctic has not been a contributor to climate change — until now, that is.”

Observing that “other reports looking to the future of the permafrost point to similarly grim conclusions,” Vox cites a recent 1,000+-page Intergovernmental Panel on Climate Change report [4] which found that even if the international community hits the IPCC target of keeping average global warming to 2.0°C by 2100,” roughly 25% of surface permafrost will still irreversibly disappear.

If average warming hits 5.0°C, about 69% could be lost, locking in feedbacks that will further accelerate the climate emergency.

These and other dire estimates, including a 2014 study which projected that “thawing permafrost could release around 120 gigatons of carbon into the atmosphere by 2100, resulting in 0.29°C of additional warming”, are “just estimates” that “come with a good deal of uncertainty,” Vox notes. That’s partly because, as the IPCC report points out, some proportion of the released carbon could in turn be reabsorbed by plants suddenly able to put down roots in regions far north of their customary range.

Even with some degree of reabsorption, however, the IPCC report confirmed that melting permafrost “will become a significant contributor to greenhouse gas emissions,” writes Vox.

While the carbon currently being emitted by the Arctic is still less than 10% of what humans generate by burning fossil fuels, the impact is “likely to grow with time, as the Arctic continues to warm,” Schuur said. “We’ve crossed the zero line.”

He added that while he and his peers don’t think that Arctic emissions will accelerate rapidly enough to make anthropogenic greenhouse gases “irrelevant,” any extra emissions will make it all the more difficult to achieve net zero by 2050 and limit average warming to 1.5°C.

And climate-altering CO2 and methane are “not all that’s lurking in the permafrost,” Vox notes. A video accompanying the news story offers chilling insight into the perils that await, especially for the 35 million people who currently call the Arctic home. Citing an outbreak of anthrax in Siberia in 2016, which infected 90 and killed a 12-year-old boy, the online news outlet points to the possibility that other deadly diseases like Spanish flu, smallpox, and bubonic plague may waken from hibernation as the permafrost melts. (Researchers now believe the source of the Siberian anthrax outbreak was a long-dead reindeer whose frozen carcass thawed and released spores into the open air.)

Citing a 2018 study in the journal Geophysical Research Letters, Vox says Arctic permafrost melt also risks the release of massive reservoirs of natural, and highly toxic, mercury—at 15 million gallons, the largest on Earth—into the oceans and food chain.

In its coverage of the NOAA report card, InsideClimate News highlights [5] the sections devoted to polar regions worst-hit (thus far) by planetary warming—including, and especially, the Bering Sea. After two back-to-back years of record low winter sea ice, the Bering Sea Elders, an Indigenous group with representatives from 38 coastal communities, spoke anxiously of empty nets and declining seal populations as the impacts of warming seas and ice loss “ricochet” through the web of life. CBC says [6] this edition of the report was the first time NOAA included observations from Indigenous fishers and hunters.

“Indigenous hunters are working harder than ever to find the food they have long relied on, and they’re sometimes making macabre discoveries: sea birds dying en masse, nets filled with fish that have rarely been seen in those areas,” writes InsideClimate.

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#1 Pingback By Melting Permafrost Turns Arctic into Net Source of Greenhouse Gases – Enjeux énergies et environnement On December 16, 2019 @ 12:41 AM

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