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The release of mercury from permafrost "could take a huge toll on the environment and the health of those living in these areas," said a co-author of the new study.
A study published Thursday in Environmental Research Letters warns that Arctic warming could unleash toxic mercury currently contained in rapidly thawing permafrost, potentially threatening the region's food supply and water quality.
Researchers from the University of Southern California's Dornsife College of Letters, Arts, and Sciences noted in the new study that the Arctic is "warming four times faster than the global average, destabilizing permafrost soils that have remained frozen for two or more years and that underlie much of the Arctic."
Mercury (Hg) deposits in the region's permafrost have "accumulated over thousands of years," the study authors noted, "and Hg in the top meter of Arctic soils potentially exceeds the total amount stored in the atmosphere, ocean, and all other soils."
Josh West, professor of Earth sciences and environmental studies at USC Dornsife and a study co-author, said in a statement that "there could be this giant mercury bomb in the Arctic waiting to explode."
The study notes that "a range of processes" can release mercury from permafrost, including riverbank erosion.
"The rivers are reburying a considerable amount of the mercury," West said. "To really get a handle on how much of a threat the mercury poses, we have to understand both the erosion and reburial processes."
Isabel Smith, a doctoral candidate at USC Dornsife and another study co-author, warned that "decades of exposure" to the toxic element, "especially with increasing levels as more mercury is released, could take a huge toll on the environment and the health of those living in these areas."
The study was published as parts of the Arctic experienced what The Washington Post's Ian Livingston described as "exceptionally high temperatures—up 30 to 40 degrees above normal."
"And it's happening as the National Oceanic and Atmospheric Administration just announced July was the 14th successive month with record-high global temperatures," Livingston wrote earlier this week. "Over the past week, temperatures soared to nearly 100 degrees Fahrenheit in Norman Wells, Canada, just 90 miles south of the Arctic Circle. Locations in Alaska set numerous record highs."
"Off the coast of Greenland, Longyearbyen, Norway, the northernmost city on Earth with a sizable population, witnessed its warmest August day, with a high of nearly 70," he added.
As our world continues to warm up, vast areas of permafrost are rapidly melting, releasing material that's been trapped for up to a million years. This includes uncountable numbers of microbes that have been lying dormant for hundreds of millennia.
To study these emerging microbes, scientists from the French National Center for Scientific Research have now revived a number of these "zombie viruses" from the Siberian permafrost, including one thought to be nearly 50,000 years old - a record age for a frozen virus returning to a state capable of infecting other organisms.
The team behind the study, led by microbiologist Jean-Marie, says these ancient viruses are potentially a significant threat to public health, and further study needs to be done to assess the danger that these infectious agents could pose as the permafrost melts.
The researchers warned it may just be the tip of the iceberg:
"One-quarter of the Northern Hemisphere is underlain by permanently frozen ground, referred to as permafrost," researchers wrote in the paper.
"Due to climate warming, irreversibly thawing permafrost is releasing organic matter frozen for up to a million years, most of which decomposes into carbon dioxide and methane, further enhancing the greenhouse effect. Part of this organic matter also consists of revived cellular microbes (prokaryotes, unicellular eukaryotes) as well as viruses that remained dormant since prehistorical times."
\u201cA 48,500-year-old virus has been revived from Siberian permafrost\nSeven viruses from the Siberian permafrost have been revived and replicated themselves in the lab \u2013 including the oldest revived so far\nhttps://t.co/mMGMXEBdsy\u201d— Samuel Jacobs (@Samuel Jacobs) 1669399746
According to Global News:
In 2014, the same researchers unearthed a 30,000-year-old virus trapped in permafrost, the BBC reported. The discovery was groundbreaking because after all that time, the virus was still able to infect organisms. But now, they've beaten their own record by reviving a virus that is 48,500 years old.
"If the authors are indeed isolating live viruses from ancient permafrost, it is likely that the even smaller, simpler mammalian viruses would also survive frozen for eons," virologist Eric Delwart from the University of California, San Francisco told New Scientist.
\u201cOkay. I've seen this movie and it didn't end well...and seriously what's that name again?\n\nPandoravirus? \ud83d\ude2c\n\n"The revived virus has been given the name Pandoravirus yedoma, which acknowledges its size and the type of permafrost soil that it was found in."\nhttps://t.co/F5yHqCTZv9\u201d— Chris Hendel (@Chris Hendel) 1669408433
While thawing permafrost on land tied to human-driven global temperature rise has generated worldwide alarm in recent years, a new study out this week is garnering attention for researchers' discoveries underwater.
"As climate change continues to reshape the Arctic, it's critical that we also understand changes in the submerged permafrost offshore."
An international team of researchers led by Charlie Paull, a geologist at the Monterey Bay Aquarium Research Institute in California, and Scott Dallimore of the Geological Survey of Canada published their findings in the peer-reviewed journal Proceedings of the National Academy of Sciences (PNAS).
Permafrost is a mix of ice, rocks, sand, and soil that remains frozen year-round. The thawing of terrestrial permafrost in places like Siberia has fueled concerns about not only damage to at-risk infrastructure but also the release of planet-heating gases as well as ancient bacteria and viruses.
However, Paull and Dallimore's team analyzed changes in the permafrost that lies beneath Arctic waters. Specifically, they focused on 10 square miles of the Canadian Beaufort Sea, using underwater vehicle and ship-mounted sonar for surveys of the seafloor in 2010, 2013, 2017, and 2019.
The researchers found craters--including one that was 92 feet deep, 738 feet long, and 312 feet wide, or bigger than a city block of six-story buildings--as well as ice-cored hills resembling "pingos" previously documented on land.
\u201cGiant, 90ft Deep Craters Are Appearing on the Arctic Seafloor. The craters are forming as a result of thawing submerged permafrost on the edge of the Beaufort Sea in northern Canada, with retreating glaciers from the last ice age driving the change. https://t.co/SLNRBwm9kh\u201d— Jeff Berardelli (@Jeff Berardelli) 1647314901
"We know that big changes are happening across the Arctic landscape, but this is the first time we've been able to deploy technology to see that changes are happening offshore too," Paull noted in a statement Monday.
Unlike terrestrial permafrost thawing, the limited data available signals that human-caused global heating is not "driving the dramatic changes in the seafloor terrain," Paull explained. "Instead, heat carried in slowly moving groundwater systems is driving these changes."
Though the team connected the seafloor changes to climatic shifts related to the planet's emergence from the last ice age nearly 12,000 ago, Paull stressed that research like his first-of-its-kind study are important in an era of rising temperatures from human activities like burning fossil fuels.
"While the underwater sinkholes we have discovered are the result of longer-term, glacial-interglacial climate cycles, we know the Arctic is warming faster than any region on Earth," he said. "As climate change continues to reshape the Arctic, it's critical that we also understand changes in the submerged permafrost offshore."
Sue Natali, Arctic Program Director and senior scientist at the Woodwell Climate Research Center in Massachusetts--who was not involved in the study--made a similar point to CNN on Monday.
"Changes described in this study are responding to events that occurred over the centennial to millennial time frame. That said, these changes can still impact climate if they are resulting in emissions of greenhouse gases as the subsea permafrost thaws," she explained.
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The underwater research was released the same day as multiple studies on terrestrial permafrost. One paper, published in the journal Nature Communications, found that alpine permafrost is expected to melt at a faster rate than Arctic permafrost under current conditions.
"Our findings were very surprising and highlight the fact that we need to put more effort into monitoring the stability of the permafrost in the alpine region," said lead author Feng Cheng of China's Peking University.
Paper co-author Carmala Garzione, dean of the University of Arizona College of Science, agreed. As she put it:
We need better and broader studies of the vulnerability of alpine regions under global warming scenarios. There's been a lot of focus on the stability of Arctic permafrost, because it covers more land area and contains a huge reservoir of organic carbon trapped in permafrost, but we also need to be aware that alpine regions stand to lose more permafrost proportionally and are important in understanding of potential carbon release under global warming scenarios.
Another study, published in the journal Nature Climate Change, warned that peatlands in Europe and Western Siberia--which store up to 39 billion tons of carbon--are closer to a climatic tipping point than previously thought.
"Our modeling shows that these fragile ecosystems are on a precipice and even moderate mitigation leads to the widespread loss of suitable climates for peat permafrost by the end of the century," said lead author Richard Fewster of the University of Leeds in the United Kingdom.
"But that doesn't mean we should throw in the towel," he said. "The rate and extent to which suitable climate are lost could be limited, and even partially reversed, by strong climate change mitigation policies."