Could,
may, might...always in the future and there’s always room for
doubt.
Usual
stuff. Of course it doesn’t do justice to the research being done
by the Zimovs, Romanovsky and others.
Exclusive:
Some Arctic Ground No Longer Freezing—Even in Winter
New
data from two Arctic sites suggest some surface layers are no longer
freezing. If that continues, greenhouse gases from permafrost could
accelerate climate change
Picture of Polygons form
above thawing permafrost in Cherskiy, Siberia
Polygons
formed by the annual freezing and thawing of ice wedges just below
the earth's surface are visible from above near the Northeast Science
Station in Cherskiy, Russia.
PHOTOGRAPH
BY KATIE ORLINSKY, NATIONAL GEOGRAPHIC
August,
2018
CHERSKIY,
RUSSIANikita Zimov was teaching students to do ecological fieldwork
in northern Siberia when he stumbled on a disturbing clue that the
frozen land might be thawing far faster than expected.
Zimov,
like his father, Sergey Zimov, has spent years running a research
station that tracks climate change in the rapidly warming Russian Far
East. So when students probed the ground and took soil samples amid
the mossy hummocks and larch forests near his home, 200 miles north
of the Arctic Circle, Nikita Zimov suspected something wasn't right.
Photograph
of Sergey Zimov measuring permafrost levels with his granddaughters
PHOTOGRAPH
BY KATIE ORLINSKY, NATIONAL GEOGRAPHIC
In
April he sent a team of workers out with heavy drills to be sure.
They bored into the soil a few feet down and found thick, slushy mud.
Zimov said that was impossible. Cherskiy, his community of 3,000
along the Kolyma River, is one of the coldest spots on Earth. Even in
late spring, ground below the surface should be frozen solid.
Except
this year, it wasn't.
Every
winter across the Arctic, the top few inches or feet of soil and rich
plant matter freezes up before thawing again in summer. Beneath this
active layer of ground extending hundreds of feet deeper sits
continuously frozen earth called permafrost, which, in places, has
stayed frozen for millennia.
But
in a region where temperatures can dip to 40 degrees below zero
Fahrenheit, the Zimovs say unusually high snowfall this year worked
like a blanket, trapping excess heat in the ground. They found
sections 30 inches deep—soils that typically freeze before
Christmas—that had stayed damp and mushy all winter. For the first
time in memory, ground that insulates deep Arctic permafrost simply
did not freeze in winter.
"This
really is astounding," says Max Holmes, an Arctic scientist with
Woods Hole Research Center in Massachusetts.
The
discovery has not been peer-reviewed or published and represents
limited data from one spot in one year. But with measurements from
another scientist nearby and one an ocean away appearing to support
the Zimovs' findings, some Arctic experts are weighing a troubling
question: Could a thaw of permafrost begin decades sooner than many
people expect in some of the Arctic's coldest, most carbon-rich
regions, releasing trapped greenhouse gases that could accelerate
human-caused climate change?
Photograph
of Nikita Zimov creating methane bubbles in a lake expanding due to
permafrost thaw
Nikita
Zimov creates methane bubbles in a lake believed to be expanding due
to thawing ground.
PHOTOGRAPH
BY KATIE ORLINSKY, NATIONAL GEOGRAPHIC
Already,
three of the last four years have been earth's hottest on record,
with 2018 on schedule to be number four. And the poles are actually
warming far faster, with areas 300 miles north of the Arctic Circle
in Norway reaching 90 degrees Fahrenheit this July. If significant
quantities of permafrost start thawing early, that would only make
things worse.
"This
is a big deal," says Ted Schuur, a permafrost expert at Northern
Arizona University. "In the permafrost world, this is a
significant milestone in a disturbing trend—like carbon in the
atmosphere reaching 400 parts per million."
Nearly
a quarter of the Northern Hemisphere's landmass sits above
permafrost. Trapped in this frozen soil and vegetation is more than
twice the carbon found in the atmosphere.
As
fossil-fuel burning warms the Earth, this ground is thawing, allowing
microbes to consume buried organic matter and release carbon dioxide
and shorter-lived methane, which is 25 times as potent a greenhouse
gas as CO2.
Permafrost
temperatures across the Arctic have been rising since at least the
1970s—so much that small-scale localized thawing is already
underway in many places. But the vast majority of this frozen land is
still insulated by an active layer of freezing and thawing ground
above it.
Eleven
miles downriver from where the Zimovs’ started their drilling,
Mathias Goeckede with Germany's Max Planck Institute for
Biogeochemistry spends weeks each summer traversing crumbling
boardwalks over spongy Siberian ground. He tracks carbon exchange
between the earth and the atmosphere.
Measurements
at his site show that snow depth there has roughly doubled in five
years. When excessive snow smothers the ground, warmth below the
surface may not dissipate during winter. Data from a drill hole on
Goeckede's site appears to capture that phenomenon: In April,
temperatures 13 inches below ground there increased roughly 10
degrees Fahrenheit in that same five-year period.
Photograph of
The
Batagaika Crater in the town of Batagay, Russia, is known as the
"hell crater" or the "gateway to the underworld.”
PHOTOGRAPH
BY KATIE ORLINSKY, NATIONAL GEOGRAPHIC
"This
is just one site, and it's just five years, so this really should be
considered just a case-study," Goeckede says. "But if you
assume it's a trend or that it might continue like this, then it's
alarming."
Thousands
of miles away, Vladimir Romanovsky saw something similar. Romanovsky,
a permafrost expert at the University of Alaska, Fairbanks, runs some
of the most extensive permafrost monitoring sites in North America,
with detailed records going back 25 years, and in some cases longer.
"For
all years before 2014, the complete freeze-up of the active layer
would happen in mid-January," he says. "Since 2014, the
freeze-up date has shifted to late February and even March."
But
this winter, Fairbanks, too, saw extremely heavy snow. And for the
first time on record, the active layer at two of Romanovsky's sites
didn't freeze at all.
"This
is really a very important threshold," he adds.
Picture
of permafrost melting
Permafrost
can be seen up close along the perimeter of the Batagaika Crater.
PHOTOGRAPH
BY KATIE ORLINSKY, NATIONAL GEOGRAPHIC
Reasons
to Be Skeptical
Of
course, Arctic weather is famously variable. A few years of heavy
snow in some regions could give way quickly to a long stretch of dry
cold years.
Some
scientists are also torn about work by the Zimovs, which isn't as
rigorous as many western researchers are accustomed to. The Zimovs’
findings didn't include temperature data, nor could they point to
long-term records. Many of the sites they examined also had been
disturbed by human activity or non-native animals, which makes soil
more susceptible to warming.
"Digging
holes in a handful of places is hardly rigorous science," says
Matt Sturm, a snow expert at the University of Alaska, Fairbanks.
Charles
Koven, a permafrost expert at Lawrence Berkeley National Laboratory,
sees cause for skepticism and more research. "I don't know what
to think without knowing more about the history of these sites,” he
says. “On the other hand, we don't want to ignore warning signs if
they're there."
What’s
more, compared to Romanovsky and Goeckede, who are measured and
methodical researchers, Sergey Zimov is something of a
catastrophist-philosopher, who leans toward pessimistic projections
and grand gestures. He and his son are the pair behind Pleistocene
Park, a region in their stretch of Siberia roamed by imported large
mammals, from bison to yaks and horses. It is part of an experiment
to mimic the mammoth steppe ecosystem that ended 12,000 years ago to
see how permafrost responds.
At
the same time, Sergey Zimov was also one of the first scientists
anywhere to show that Siberia contains enormous reserves of
especially carbon-rich permafrost. And he has worked in Cherskiy for
more than 40 years and is held in high regard by many researchers.
"He
knows that landscape so well that he is very rarely wrong," says
Katey Walter Anthony, an associate professor at the University of
Alaska, Fairbanks, who studies methane in Arctic lakes. "For him
to believe a process is important is valuable."
Romanovsky
knows the Zimovs, too, and says that while he wishes their work
included temperature data, checking freeze depth is a sound approach.
"That's still a convincing method," Romanovsky says. "For
me, it just means it's not 100 percent."
It's
also not clear how widespread a region Romanovsky's and the Zimovs'
findings represent. It is a small sample size.
But
Romanovsky says his sites were chosen because they fairly represent
central Alaska.
"So,
we assume that freeze-up didn't happen this winter within large areas
in the Alaskan Interior," he says.
And
even scientists uncomfortable with the limited data say the
possibility that something so fundamental could change so quickly
gives them pause.
"It's
worrisome," says Sue Natali, a permafrost expert, also with
Woods Hole, who saw an active layer not re-freeze recently during a
research trip to Alaska's Yukon region. "When we see things
happening that haven't happened in the lifetime of the scientists
studying them, that should be a concern."
Photograph
of permafrost found near the Northeast Science Station
Most
permafrost remains frozen. But some, in northern parts of Siberia and
several other sites in the Arctic, is at risk of thawing far faster
than expected, threatening to release large quantities of carbon
dioxide and methane.
PHOTOGRAPH
BY KATIE ORLINSKY, NATIONAL GEOGRAPHIC
An
Accelerating Cycle
The
stakes are high. If a region's active layer stops freezing
consistently, consequences can be swift. Once unfrozen, soil microbes
in the active layer can decompose organic material and release
greenhouse gases year-round—not just in summer. And it exposes
permafrost below to more heat so that layer, too, can begin thawing
and releasing gases.
In
ice-rich soils, such as in Siberia, the ground may slump. That can
buckle roads and buildings and cause ice cellars to collapse. Such
depressions also alter the landscape by forming troughs and bowls
where snow can accumulate, making the ground even warmer in winter.
Those troughs can fill with rain and snowmelt, forming new wetlands
and tundra lakes, both of which expel large amounts of methane.
And
the movement of all this water, above and below ground, can transport
large amounts of heat, hastening thawing. Permafrost collapse can
begin feeding on itself, releasing more greenhouse gases, which fuel
more warming.
Picture of permafrost
melting
The
Batagaika Crater is one of the few places to see a wall of
permafrost—and whether it's thawing—up close. Scientists study
the area for clues about climate change in the Arctic and how it may
affect the rest of the planet.
PHOTOGRAPH
BY KATIE ORLINSKY, NATIONAL GEOGRAPHIC
No
one expects permafrost will ever release all its stored carbon. Most
models suggest just 10 to 20 percent at most would escape even at
high human emissions scenarios.
But
more than a dozen Arctic climate scientists contacted by National
Geographic agree that this year's active-layer data highlights the
limitations of global climate models. The sophisticated computer
programs that forecast future climate scenarios often used by
government decision-makers simply can't capture major changes in
permafrost.
"When
we simulate these things there are a number of processes the models
don't include—processes the multiply the transfer of heat,"
says Daniel Fortier, an associate professor of geography with the
University of Montreal. "I think it's safe to say that things
are happening faster than we were expecting."
CAUSES
AND EFFECTS OF CLIMATE CHANGE
What
causes climate change (also known as global warming)? And what are
the effects of climate change? Learn the human impact and
consequences of climate change for the environment, and our lives.
For
example, scientists have long known that loss of sea ice and rising
temperatures will lead to more Arctic snow over time, which models
are able to incorporate. But those same simulations are far less
reliable when trying to track the cascading shifts in soil types,
surface vegetation, melting ice, and the flow of water that will come
from rising temperatures and all that snow, all of which could
substantially hasten permafrost thaw.
"The
models can't handle those landscape-scale changes, all of the
processes that could lead to rapid change," says David Lawrence,
a permafrost modeler with the National Center for Atmospheric
Research in Boulder. "And it's going to be a long time before
they can."
By
the time some changes are detected, a significant transition may be
underway, he says. That means the public and policymakers may not
grasp the real risks.
"Most
models don't project major carbon releases until beyond 2100,"
Walter Anthony says. That may be the case. But it's also possible,
she says, that they "could actually happen in my children's
lifetime—or my own."
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