What happens when the Arctic permafrost melts? - Brendan Rogers and Jessica Howard
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-called “drunken 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.
