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

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