Permafrost is ground that stays frozen for at least two consecutive years, and it covers a large share of the northern hemisphere. It holds enormous quantities of organic carbon, accumulated over thousands of years. As the ground warms, that carbon can be released as carbon dioxide and methane, adding to the warming that caused the thaw. The process is slow, and its scale is the reason it matters.
How much carbon is stored
Estimates put the carbon in northern permafrost at roughly twice the amount currently in the atmosphere. Most of it is locked in frozen soil and sediments, where decomposition is very slow. Thawing exposes that material to microbes, which convert it into greenhouse gases.
Why the release is gradual
Thaw does not happen everywhere at once. It spreads from the surface downward and from the edges of frozen areas inward. Decomposition also depends on water and temperature, so the release varies by location and season. The result is a slow, uneven process rather than a sudden pulse.
When thawing soil is waterlogged, decomposition produces methane, which traps heat far more effectively than carbon dioxide over short periods. When it is well drained, carbon dioxide dominates. The balance between the two depends on local conditions, which makes the total effect difficult to predict.
What the feedback means
The concern is a feedback loop: warming causes thaw, thaw releases greenhouse gases, and those gases cause more warming. Scientists describe this as a carbon-cycle feedback, and it is one of the uncertainties that make high-warming scenarios worse than they first appear.
Permafrost regions are vast, remote and sparsely instrumented. Measuring carbon release requires field stations, aircraft and satellite data, and each has limitations. Estimates therefore carry wide uncertainty, which is often lost in public discussion of a single dramatic number.
The infrastructure dimension
Thaw also damages roads, buildings and pipelines built on frozen ground, a problem known as thaw subsidence. The costs fall on communities and companies in the Arctic, and they are already visible in some regions. This is a more immediate consequence than the long-term carbon release.
The indicators worth following are ground temperature, active-layer thickness and measured carbon fluxes at long-term monitoring sites. Those measurements, rather than model projections alone, will show how quickly the release is accelerating and where the largest changes are occurring.
The role of Indigenous knowledge
Communities across the Arctic have observed environmental change for generations, and their knowledge often precedes scientific measurement. Land users notice shifts in snow, ice and wildlife that instruments may miss. Incorporating that knowledge improves monitoring and builds trust, and it requires engaging communities as partners rather than as sources of data.
Permafrost emissions cannot be stopped by local action, because the driver is global warming. Policy can support monitoring, fund adaptation for infrastructure and include permafrost in climate assessments so that its contribution is not overlooked. Those measures do not reverse the thaw; they improve the information and reduce the damage.
The role of monitoring networks
Long-term monitoring sites provide the measurements that models depend on. They are expensive to maintain, and funding is often insecure, which puts the record at risk. Expanding and sustaining these networks is one of the more useful things a government can do, even though it produces no dramatic announcement.
Wide uncertainty in permafrost emissions is not a reason to ignore them. It means that planning should be robust to a range of outcomes, and that monitoring should continue so the range narrows. Treating uncertainty as a reason for inaction is the error that the science is designed to prevent.
The Arctic communities
The people most affected by thaw are those who live on the ground that is changing. Their housing, transport and food systems depend on frozen conditions, and adaptation costs fall on small communities with limited budgets. Permafrost is often discussed as a global carbon issue, and for the Arctic it is also an immediate question of whether buildings stay level and roads stay passable.
Why the stakes are global
Permafrost is a regional phenomenon with global consequences. The carbon it releases enters the same atmosphere that warms the ground, which makes it part of a feedback that no single country can manage alone. That is why it appears in international climate assessments and why monitoring is treated as a shared responsibility. The practical response combines continued measurement, support for Arctic adaptation and, above all, reductions in the emissions that drive the thaw in the first place.
For policymakers outside the Arctic, the lesson is that some consequences of warming are slow, cumulative and difficult to reverse. Permafrost is one of them, and it rewards attention now rather than after the effects are obvious.
This report draws on the IPCC and the National Snow and Ice Data Center.
Image: German Wikipedia contributor, “HylgeriaK” · CC0 · via Wikimedia Commons.