
The Thaw
Speeds Up
The unexpectedly rapid collapse of ice-rich permafrost in the Arctic could pump billions of additional tons of methane and carbon dioxide into the atmosphere every year—a threat that has yet to be fully accounted for in climate models. Scientists are discovering destabilized landscapes where permafrost that once thawed a few inches a year can now abruptly thaw up to 10 feet within days or weeks, creating wetlands in once frozen regions and accelerating emissions from up to 1,600 gigatons of carbon still locked underground.
PACIFIC
Ocean
North
America
Arctic
Ocean
North
Pole
ATLANTIC
Ocean
Carbon content (in tons per acre)
in permafrost susceptible to:
Gradual thaw
Abrupt thaw
Thawing fast and slow
Twenty percent of permafrost is ice rich and at risk of abrupt thaw, which could double the amount of greenhouse gases released.
870 gigatons
of carbon
in atmosphere
1,600 gigatons
in permafrost
A landscape revolution
As ice buried within frozen ground melts, the meltwater moves through the permafrost, thawing it further and causing the ground above it to slump. Ponds form and later drain, hastening the collapse of even more frozen soils. The process is called abrupt thaw, and it’s accelerating the release of trapped carbon—and visibly changing the Arctic.
How polygonal permafrost forms—
and thaws
Active
layer
The active layer freezes in winter, creating cracks deep in the soil.
Permafrost
Water fills in the cracks, which freeze and expand, forming ice wedges.
Growing ice wedges push soil upward, forming polygonal patterns.
Wedges melt, the soil above them collapses, and water accumulates.
The active layer grows, wedges shrink, and the landscape drains.
Scenes of thawing
Burning tundra
Tundra fires, once rare, are becoming more common as a warming climate greens the Arctic. Fires thaw the top layer of soil and rapidly degrade the permafrost below.
Thaw slumps
When permafrost thaws near a hillside or a stream or river, it can trigger a landslide. These so-called thaw slumps quickly expose more permafrost, rapidly accelerating further thawing.
Active layer
The top layer of soil thaws and refreezes annually. This layer is deepening across the Arctic as permafrost turns into unfrozen soil.
Spreading lakes
Lakes that once froze solid are now
partially liquid in winter and widening as permafrost thaws. The warmth allows microbes to feed on organic material year-round, releasing greenhouse gases.
Permafrost polygons
The distinctive, puzzle-like pattern of some Arctic landscapes is shaped by ice wedges beneath the surface.
Ice wedges
Formed over millennia, as soil froze and cracked in winter and filled with water in spring, they’re now degrading in as little as a few years.
Beaver ponds
A warming tundra has more and larger shrubs, which attract beavers. They dam up creeks, creating new ponds and lakes. That speeds up permafrost collapse and alters the landscape.
New foragers
As shrubs spread out and grow taller, they attract large herbivores such as moose, which in turn affect vegetation growth patterns.
New life in the water
Warmer water and new aquatic habitats may allow fish such as salmon to become established in the Arctic.
Jason Treat, MattHEW W. Chwastyk, and Ryan Williams, NGM STAFF. Art: TomአMüller.
Sources: David Olefeldt AND OTHERS, Nature COmmunications, 2016; Merritt Turetsky AND OTHERS, Nature, 2019; Róisín Commane, Columbia University; Ted Schuur, Northern Arizona University; EPA; Ken Tape and Anna Liljedahl, University of Alaska Fairbanks

The Thaw Speeds Up
The unexpectedly rapid collapse of ice-rich permafrost in the Arctic could pump billions of additional tons of methane and carbon dioxide into the atmosphere every year—a threat that has yet to be fully accounted for in climate models. Scientists are discovering destabilized landscapes where permafrost that once thawed a few inches a year can now abruptly thaw up to 10 feet within days or weeks, creating wetlands in once frozen regions and accelerating emissions from up to 1,600 gigatons of carbon still locked underground.
150°E
150°W
180°
Bering Sea
Sea of
Okhotsk
PACIFIC
Ocean
Newtok
Gulf of
Alaska
Alaska
(U.S.)
Pleistocene
Park
Fairbanks
Cherskiy
Ambarchik Bay
E. Siberian
Sea
Kaktovik
North
America
Batagaika
crater
Beaufort
Sea
Lake
Baikal
Banks I.
120°
120°
Arctic Ocean
Victoria I.
Canada
Queen
Elizabeth
Islands
North Pole
90°
90°
Russia
Hudson
Bay
Baffin
Bay
60°
Barents
Sea
30°E
Lakselv
60°
Labrador
Sea
Iceland
Norway
30°W
60°
ATLANTIC
Ocean
DENMARK
0°
Carbon content (in tons per acre)
in permafrost susceptible to:
870 gigatons
of carbon
in atmosphere
Thawing fast and slow
Twenty percent of permafrost is ice rich and at risk of abrupt thaw, which could double the amount of greenhouse gases released.
Gradual
thaw
Abrupt
thaw
Powering
43.5 average U.S. homes for a year releases about 400 tons of carbon.
Greater than 400
300-400
200-299
100-199
Less than 100
1,600 gigatons
in permafrost
A landscape revolution
As ice buried within frozen ground melts, the meltwater moves through the permafrost, thawing it further and causing the ground above it to slump. Ponds form and later drain, hastening the collapse of even more frozen soils. The process is called abrupt thaw, and it’s accelerating the release of trapped carbon—and visibly changing the Arctic.
Scenes of thawing
Thaw slumps
Beaver ponds
Spreading lakes
Burning tundra
When permafrost thaws near a hillside or a stream or river, it can trigger a landslide. These so-called thaw slumps quickly expose more permafrost, rapidly accelerating further thawing.
A warming tundra has more and larger shrubs, which attract beavers. They dam up creeks, creating new ponds and lakes. That speeds up permafrost collapse and alters the landscape.
Tundra fires, once rare, are becoming more common as a warming climate greens the Arctic. Fires thaw the top layer of soil and rapidly degrade the permafrost below.
Lakes that once froze solid are now
partially liquid in winter and widening as permafrost thaws. The warmth allows microbes to feed on organic material year-round, releasing greenhouse gases.
How polygonal
permafrost forms—
and thaws
Active
layer
New foragers
As shrubs spread out and grow taller, they attract large herbivores such as moose, which in turn affect vegetation growth patterns.
Permafrost polygons
The distinctive, puzzle-like pattern of some Arctic landscapes is shaped by ice wedges beneath the surface.
The active layer freezes in winter, creating cracks deep in the soil.
Permafrost
Water fills in the cracks, which freeze and expand, forming ice wedges.
Active layer
The top layer of soil thaws and refreezes annually. This layer is deepening across the Arctic as permafrost turns into unfrozen soil.
Growing ice wedges push soil upward, forming polygonal patterns.
New life in the water
Warmer water and new aquatic habitats may allow fish such as salmon to become established in
the Arctic.
Ice wedges
Formed over millennia, as soil froze and cracked in winter and filled with water in spring, they’re now degrading in as little as a few years.
Wedges melt, the soil above them collapses, and water accumulates.
The active layer grows, wedges shrink, and the landscape drains.
Jason Treat, MattHEW W. Chwastyk, and Ryan Williams, NGM STAFF.
Art: TomአMüller. Sources: David Olefeldt AND OTHERS, Nature COmmunications, 2016; Merritt Turetsky AND OTHERS, Nature, 2019; Róisín Commane, Columbia University; Ted Schuur, Northern Arizona University; EPA; Ken Tape and Anna Liljedahl, University of Alaska Fairbanks
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