Fourteen million square kilometres of the Northern Hemisphere have not thawed in living memory — and the map of that frozen ring is not a circle around the pole. It is lopsided, it runs deeper than most mines, and the carbon buried inside it is roughly twice what is in the air above it.
1,400–1,600
Gigatonnes of organic carbon
Held in the soils of the northern permafrost region — nearly twice the carbon in Earth’s entire atmosphere. Schuur et al., BioScience 2008 / Nature 2015.
Permafrost is not ice: it is any ground — silt, gravel, bedrock — held at or below 0 °C for two straight years. Some of it has held that temperature for hundreds of thousands.
Northern Hemisphere permafrost, polar azimuthal view, Greenwich meridian at the bottom. One hue, light to dark, by the share of ground that stays frozen. Schematic outlines; every place name and figure is real. Zones after NSIDC; areas after Obu (2021).
01 — How much
The map is larger than the thing it maps
Almost every popular account says permafrost covers a quarter of the Northern Hemisphere. That is the size of the region where permafrost occurs. The ground actually frozen inside that region is about a third smaller.
Northern Hemisphere, share of exposed land — Obu (2021)
Permafrost region
21.0 M km²
→ share of NH land
22.0 %
Permafrost area
13.9 M km²
→ share of NH land
14.7 %
In Eurasia
~65 % of it
In N. America + Greenland
~35 % of it
Obu found that more than 80% of published studies quote the larger number — an overstatement of roughly 6 million km², about the area of Australia minus Queensland. The difference is not a rounding error; it is the sporadic and isolated zones, where frozen ground is the exception rather than the rule.
02 — The four grades of frozen
A spectrum, not a boundary
Cartographers do not draw a line where permafrost stops. They draw four bands, graded by what fraction of the ground beneath your feet is frozen.
Share of ground underlain by permafrost — NSIDC zone classes
ISOLATEDunder 10% frozen
SPORADIC10–50% frozen
DISCONTINUOUS50–90% frozen
CONTINUOUS90–100% frozen
On the map above, this is the light-to-dark ramp. Walk south across it and the frozen ground does not end — it thins, breaks into patches, hides under north-facing slopes and peat bogs, and finally disappears. The darkest band, continuous permafrost, is where the ground is frozen essentially everywhere: Greenland’s ice-free margin, Svalbard, northern Siberia, the Canadian Arctic.
03 — Depth
Down to a kilometre and a half
The map shows area. The number that actually surprises people is the third dimension.
Vertical structure — thickness ranges, NSIDC
Active layer
0.3–2 m — thaws and refreezes every year
Typical Arctic lowland
tens to a few hundred metres
Alaska, north slope
up to ~650 m
Northern Siberia
greater than 1,500 m
Why is the deepest permafrost in Siberia rather than Canada? Because during the Pleistocene, thick ice sheets sat on top of much of North America and insulated the ground beneath them. Central and eastern Siberia stayed largely unglaciated — bare, dry and brutally cold — and the cold drove straight down, year after year, for hundreds of thousands of years.
04 — Temperature
Every zone on the map is warming
A global network of boreholes measures permafrost temperature at the depth where the seasons no longer reach. Between 2007 and 2016, every category warmed.
Change in ground temperature at zero annual amplitude, 2007–2016 (°C) — Biskaborn et al. 2019
Continuous zone
+0.39 °C
Antarctica
+0.37 °C
All sites, global mean
+0.29 °C
Discontinuous zone
+0.20 °C
Mountain permafrost
+0.19 °C
Note the shape of it: the coldest ground warmed fastest. Continuous permafrost gained +0.39 °C in a decade while discontinuous permafrost gained half that — because warmer, patchier ground near 0 °C spends its energy melting ice rather than raising temperature. Above it, the Arctic air has warmed 3.8 times faster than the global average since 1979 (Rantanen et al., 2022).
05 — What is built on top
Foundations poured into a temperature
Arctic engineering assumes the ground stays frozen. Pile foundations, airstrips, pipelines, tailings dams and whole cities are anchored in a material defined by a number on a thermometer.
4M
People
Living in the permafrost domain in areas with high potential for near-surface thaw by 2050. Hjort et al., 2018.
70%
Of infrastructure
Of current infrastructure in the permafrost domain sits in those same high-hazard areas; one-third of all pan-Arctic infrastructure. Hjort et al., 2018.
45%
Of Russian Arctic fields
Share of hydrocarbon extraction fields in the Russian Arctic in regions where thaw-driven ground instability can cause severe damage. Hjort et al., 2018.
Batagay, Yakutia — 67.6°N
The megaslump
Where the frozen ground gives way completely it does not subside gently — it collapses. The Batagay slump, opened by forest clearance in the 1960s, was roughly a kilometre long and about 990 m wide as of 2023, with a headwall tens of metres high. It loses on the order of one million cubic metres of frozen ground and ice a year. Kizyakov et al., Geomorphology 2024. It is marked on the map.
Norilsk — 69.3°N
21,000 tonnes
In May 2020 a fuel tank at a Norilsk power plant failed and released about 21,000 tonnes of diesel into Arctic soil and rivers. Attribution is genuinely contested: a review commissioned by the operator listed rising permafrost temperature and reduced soil bearing capacity among the causes; the Russian regulator’s official finding emphasised tank corrosion and human error. Both readings can be true of the same tank.
06 — The carbon
Two skies, buried
Cold ground does not decompose. Forty thousand years of plant and animal matter has been accumulating in the frozen north without ever finishing the process of rotting.
Carbon accounting, all four bars on one scale — Schuur et al.; IPCC AR6 WGI
Permafrost-region soils
1,400–1,600 GtC
Earth’s atmosphere
≈ half as much
Released per °C by 2100
~18 GtC •
→ likely range
3–41 GtC •
Nobody expects all of it to move. The IPCC’s Sixth Assessment gives a modelled figure of roughly 18 GtC released per degree of global warming by 2100 — a likely range of 3 to 41 GtC, which is about 11 to 150 Gt of CO₂. The uncertainty band is wider than most of the world’s annual emissions budgets, which is precisely the problem.
What to notice on the map
The frozen ring is not centred on the pole
Murmansk sits at 69°N on ground that is barely frozen. Yakutsk sits at 62°N on ground frozen to about 1,500 m. The North Atlantic Drift pushes warm water up one flank of the Arctic; continental Siberia has no ocean to warm it. Latitude is a poor predictor of frozen ground — this map is the proof.
The darkest band hugs the coasts and the great river deltas — the Lena, the Yenisei, the Mackenzie. That is also where almost all Arctic settlement, shipping and resource extraction is. The hazard map and the map of human presence are nearly the same map.
Greenland and Svalbard are solid dark. Permafrost is not only a Siberian phenomenon; it is the default state of any high-latitude ground that is not under a warm ocean or a thick ice sheet.
The frame stops at 45°N, which hides the other half of the story. The Tibetan Plateau holds the largest expanse of high-altitude permafrost on Earth, at latitudes closer to Cairo than to the Arctic Circle. Elevation does what latitude does. A circumpolar projection simply cannot show it.