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As climate change warms the Arctic, melting ice could release dangerous chemicals and radioactive materials from the Cold War. The disappearance of permafrost could also release viruses and bacteria that have slept under the arctic ice for tens of thousands of years, according to a new study.
Looking at historical records and previous studies on contamination, researchers found that in addition to fallout from nuclear explosions and pollutants such as mercury, arsenic and DDT, so-called Methuselah microorganisms – microbes that have been locked in permafrost for millennia – can wake up if climate change melts arctic ice and germs defrost. This could free bacteria that are resistant to antibiotics, or introduce virus that humans have never encountered before.
Related: Melting images: the Earth’s ice disappearing
The term “permafrost” describes soil that has been continuously frozen for two or more years and may include single earth or earth mixed with ice and covered with snow, according to the National Snow and Ice Data Center (NSIDC). Permafrost covers approximately 9 million square miles (23 million square kilometers) of the northern hemisphere, and its thickness ranges from less than 3 feet (1 meter) to over 3,000 feet (1,000 m), according to the NSIDC .
Most of the arctic permafrost cover has persisted for 800,000 to 1 million years, but climate change is eating away at even some of the oldest ice reserves. Warming in the Arctic is progressing at least twice as fast as elsewhere in the world, and the past 15 years have warmed and melted the region to the point where the frozen landscape has constantly transformed, according to Arctic Bulletin 2020 published by the National Oceanic and Atmospheric Administration (NOAA).
One of the known dangers of arctic warming is the release of vast reserves of greenhouse gas. Melting permafrost releases millions of tonnes of carbon dioxide and methane each year, and this amount is likely to increase as the Earth continues to warm, Live science reported in 2020.
But until now, scientists have not known the extent of the dangers posed by pollutants stored in permafrost – “everything from potential microbes and viruses to nuclear waste, chemicals and Mercury“said lead author of the study Kimberley Miner, a scientific systems engineer at NASA’s Jet Propulsion Lab at the California Institute of Technology (JPL-Caltech).
“Hardly anyone has ever put all of these different things together,” Miner told Live Science.
What’s in the permafrost?
Scientists reviewed hundreds of previous studies “to catalog the emerging microbial, viral and chemical hazards in the new Arctic and recommend research priorities to quantify and address these risks,” the authors wrote.
Since nuclear testing began in the 1950s, radioactive material has been dumped in the Arctic. During the Cold War, from the end of World War II to 1991, the United States and the Soviet Union carried out nuclear tests and research in the Arctic which left high levels of radioactive waste in the ground and permafrost, the researchers found.
The detonations of the Soviet Union in the archipelago of Novaya Zemlya, between 1959 and 1991, released 265 megatons of nuclear energy; the Russians also scuttled more than 100 decommissioned nuclear submarines in the Barents and Kara seas, releasing radioactive substances plutonium and cesium which can be detected today in seabed sediments and ice caps, as well as in plants and soil beneath glaciers, according to the study.
United States Century Camp, a nuclear research center of Greenland, generated radioactive waste that was dumped under the ice when the site was decommissioned in 1967. This ice is now receding rapidly, with losses of about 268 tonnes (243 metric tonnes) per year, as the Arctic recedes. warms up. And when an American B-52 bomber crashed near Danish Thule Air Base in Greenland in 1968, its nuclear missile payload ruptured and was released. uranium and plutonium from four bombs in the ice cap. Radiation levels in the Arctic could remain harmful for up to 2,500, the study’s authors reported.
Related: How radioactive is the human body?
Decades of arctic mining over tens of thousands of square kilometers have also left behind wastes rich in toxic heavy metals such as mercury, arsenic and nickel. These pollutants have since sunk deep into arctic soil and could threaten wildlife and human communities in Alaska, Canada, Greenland, Scandinavia and Russia, according to the study. It is estimated that 880,000 tonnes (800,000 metric tonnes) of mercury alone are stored in permafrost, and current warming trends could increase mercury emissions in the Arctic by up to 200% by 2300, according to Researchers.
Arctic permafrost also traps reservoirs of dangerous chemicals that were banned in the early 2000s, such as the insecticide DDT (dichloro-diphenyl-trichloroethane) and PCBs (polychlorinated biphenyls), a group of chemicals widely used in liquids. cooling. These persistent organic pollutants, or POPs, and others, made their way to the Arctic through the atmosphere and over time concentrated in the permafrost. However, “few studies have traced the transport and risks of POPs”, suggesting that “the impact of these chemicals in arctic systems is underestimated”, according to the study.
Microbial threats could also be lurking in arctic permafrost. Because arctic microbes have evolved to survive sub-zero temperatures with minimal access to nutrients or water, many are able to come back to life even after thousands of years in deep frost. In previous studies, other researchers have revived bacterial populations in permafrost dating back to 30,000, 120,000 and even a million years ago, the scientists reported.
Find the risk
But identifying pollutants in permafrost is only part of calculating their risk to the Arctic and beyond; the other part of the equation is how quickly permafrost melts, Miner said.
“There’s a gradual thaw, which is just a year-over-year thaw slowly descending from the top. And then there’s a sudden thaw, where, for example, you can lose an entire side of a permafrost hill in a series of weeks. That’s the kind of difference that will have to be mapped in order to understand when and how these things can emerge, “Miner said.
Another important factor is that different pollutants present varying levels of risk depending on the amount of pollutants, the length of exposure and how people and wildlife may come into contact with them, she said. added. For this reason, a next step for researchers might be to assign a risk profile to recently identified pollutants in permafrost. But it’s harder to assess the risks of Methuselah germs from permafrost, because it’s unclear what types of bacteria and viruses might emerge from ancient frozen ground.
“We have a very little understanding of what kind of extremophiles – microbes that live in many different conditions for a long time – have the potential to reappear,” Miner said. “These are microbes that have co-evolved with things like giant sloths or mammoths, and we have no idea what they might do once released into our ecosystems.”
In the long term, it would be better to keep these organisms and pollutants in their permafrost graves rather than trying to contain them once they escape, Miner said.
“It is absolutely essential to make sure that we do everything in our power to keep the permafrost – and the Arctic generally – frozen,” she said. “It would be so much easier if we didn’t have to deal with one of them, in addition to the long term remedial proposals.”
The results were published on September 30 in the journal Nature Climate Change.
Originally posted on Live Science.
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