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  • In June 2022, a gold miner in the Canadian Yukon

  • made a remarkable discovery.

  • While working on the traditional lands of the Tr'ondëk Hwëch'in First Nation,

  • he uncovered the exceptionally well-preserved frozen remains

  • of a woolly mammoth calf that died 30,000 years ago.

  • But this find isn't the only of its kind

  • because the Arctic holds many buried secrets...

  • About 15% of the Northern Hemisphere contains permafrost

  • that is, ground that doesn't thaw seasonally,

  • but has instead stayed frozen for at least two years

  • and, typically, much longer.

  • The oldest permafrost yet discovered is located in the Yukon

  • and has been frozen for 740,000 years.

  • The thickness of permafrost also ranges,

  • from just 1 meter in some areas to over a kilometer in others.

  • And permafrost is exceptionally good at preserving biological remains.

  • If any ice crystals are close to remains buried in permafrost,

  • they help draw moisture away.

  • And microorganisms that would otherwise quickly decompose

  • plant and animal tissues operate at slower metabolic rates

  • in these subfreezing temperatures.

  • The outcome is that, instead of having to rely on fossilized skeletons

  • to extrapolate what an ancient animal might have looked like,

  • permafrost can sometimes offer scientists literal freeze-frames of times long gone.

  • In 2016, another gold miner came face-to-face

  • with a 7-week-old grey wolf pup

  • that had been preserved in permafrost for 57,000 years.

  • Researchers learned that she'd been feasting on salmon,

  • and think she died quickly,

  • possibly when the den she was nestled in collapsed.

  • In 2020, reindeer herders encountered remains

  • that unmistakably belonged to a bear.

  • But it turned out that they were as much as 39,500 years old.

  • They belonged to a cave bear.

  • Its species went extinct about 24,000 years ago.

  • Before this, scientists had only ever seen cave bear skeletal remains.

  • Even incomplete animal remains found in permafrost

  • have yielded incredible results.

  • In 2021, researchers identified a new species of mammoth

  • by reconstructing DNA sequences from 1.6-million-year-old mammoth teeth

  • making it the oldest sequenced DNA on record.

  • And extraordinary finds go beyond the animal kingdom:

  • in 2012, scientists successfully regenerated a flowering tundra plant

  • from seeds they found encased in 32,000-year-old squirrel burrows.

  • However, all the prehistoric remains we have yet to discover in permafrost

  • are at risk, along with much more, because permafrost is thawing rapidly.

  • Climate change is warming the Arctic at 3 to 4 times the rate

  • of the rest of the world.

  • And an increased frequency in extreme weather events,

  • like lightning and wildfires,

  • is burning the plants and soil that otherwise help to keep permafrost cool.

  • When permafrost thaws, it has concerning and far-reaching effects.

  • The ground can fracture and collapse in on itself,

  • and the landscape can experience flooding and erosion,

  • making previously stable trees tilt and form so-calleddrunken forests.”

  • It can also trigger massive landslides and threaten critical infrastructure.

  • By the year 2050, permafrost thaw may endanger 3.6 million people.

  • This includes many Indigenous and First Nations people

  • who have lived across the Arctic region since time immemorial.

  • Right now, they're dealing with difficult decisions

  • about how to protect their communities and traditional ways of life

  • in the face of climate change.

  • The effects of thawing will also extend far beyond the Arctic.

  • This is because permafrost stores an estimated 1.6 trillion tons of carbon.

  • That's over double the amount in Earth's atmosphere as of 2022—

  • and more than humans have ever released by burning fossil fuels.

  • Permafrost is one of the world's largest carbon reservoirs

  • because of all the organic material it contains

  • some as intact remains,

  • but much of it in the form of partially decomposed soils and sediments.

  • When it begins thawing,

  • microorganisms decompose organic material more efficiently,

  • and release gases like carbon dioxide and methane.

  • This triggers a feedback loop:

  • as more gases are released, the climate warms,

  • causing more permafrost to thaw and release even more greenhouse gases.

  • To preserve snapshots of what the planet was like thousands of years ago

  • when mammoths and cave bears trod its terrain

  • and to support the diversity of life on Earth thousands of years to come,

  • the Arctic needs to keep its cool.

In June 2022, a gold miner in the Canadian Yukon

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Ice Age mummies frozen in time - Brendan Rogers and Jessica Howard

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    shuting1215 に公開 2023 年 02 月 26 日
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