The Arctic is thawing – and what is being released from beneath the frozen ground could make global warming even harder to stop. The climate crisis is not only heating the air above us; it is beginning to unlock vast stores of ancient carbon buried deep within frozen ground, releasing greenhouse gases that could add further pressure to a warming planet by pushing the temperatures even higher.
For thousands of years, vast stretches of the Arctic have remained locked in a deep freeze. Beneath the tundra lies an enormous store of ancient organic matter, preserved in permanently frozen soil. Now, that frozen reservoir is beginning to thaw.
And as the ground warms, another climate threat emerges: methane — a powerful greenhouse gas and the second-largest contributor to global warming after carbon dioxide (CO₂). Methane traps heat far more effectively than CO₂ over the short term, but it remains in the atmosphere for a much shorter period, breaking down in roughly 10–15 years. That combination makes methane especially important when the goal is to slow warming in the near term.
But methane is only part of the story. As permafrost thaws, ancient plant remains that have been locked away for thousands of years can become exposed to microbes. Their decomposition releases both carbon dioxide and methane, depending partly on whether the newly thawed landscape becomes dry or waterlogged. Dry conditions tend to favour CO₂ emissions, while wetlands and lakes can produce more methane.
The danger, therefore, lies not only in the greenhouse gases humanity is putting into the atmosphere, but also in what a warming Earth may begin to release on its own. As frozen ground gives way to thawing landscapes, scientists are watching a potentially powerful climate feedback unfold – one in which warming triggers thaw, thaw releases greenhouse gases, and those emissions contribute to further warming.
Permafrost Methane Emissions: Carbon. Ancient carbon.
When permafrost thaws, the ancient carbon trapped inside it can be released into the atmosphere. It may emerge as carbon dioxide (CO₂) or, in wet conditions, as methane – a powerful greenhouse gas that can speed up warming in the near term. Hence, some of it can emerge as carbon dioxide. Some can emerge as methane.
It traps heat much more efficiently than carbon dioxide, although it remains in the atmosphere for a considerably shorter time. That combination gives methane an unusual importance in the climate fight. The world is already struggling to slow global heating. Now nature itself may begin adding fuel to the fire.
The Methane Problem the World Cannot Ignore
Methane comes primarily from agriculture, fossil-fuel production and waste management. Cutting these emissions can therefore provide an important opportunity to limit near-term warming. Yet climate strategies have often concentrated overwhelmingly on CO₂, while methane is frequently converted into a single measure known as CO₂ equivalent. That approach is useful for comparing different greenhouse gases, but it can also hide an important difference: CO₂ and methane do not behave the same way in the atmosphere.
CO₂ can remain influential for centuries, while methane breaks down faster. As a result, the climate effect of methane depends on the timeframe and assumptions used to measure it. A new study published in Communications Earth & Environment takes a different approach, separating CO₂ and methane rather than treating them as interchangeable. Its findings are striking: even under the most ambitious existing national net-zero targets, failing to reduce methane could push peak warming above 1.85°C. The research concludes that stringent methane reductions need to accompany net-zero CO₂ targets if warming is to remain well below 2°C.
Why the Frozen North Matters
The methane story becomes even more alarming when it reaches the Arctic. Permafrost is ground that remains frozen throughout the year. It covers an enormous region — about 20 million square kilometres, roughly five times the size of the European Union — across places including Siberia, Canada, Alaska and parts of Europe. But this frozen landscape is more than ice and soil.
It is a gigantic carbon store. According to Professor Gustaf Hugelius of Stockholm University’s Bolin Centre for Climate Research, permafrost contains around 1,500 gigatons of carbon – three times more than all the living vegetation on Earth.
For millennia, the frozen ground effectively acted like a natural freezer, locking away ancient plant material. Now, climate warming is opening that freezer door.
When the Ground Begins to Breathe
As humans burn coal, oil and gas and warm the climate, permafrost begins to thaw. Ancient plant material that was safely locked inside the frozen soil becomes exposed to microbes. Those microbes break down the organic matter and release CO₂ and methane into the atmosphere.
The result is a dangerous feedback loop: warming → permafrost thaw → greenhouse-gas release → more warming → further thaw.
And the damage may not simply reverse when temperatures eventually fall. When underground ice melts, the surface can collapse, creating lakes, wetlands and river gullies known as thermokarsts. These landscapes have different hydrology and thermal properties, meaning that once certain thresholds are crossed, the original frozen system may not return for hundreds of years.
A Tipping Point That Does Not Happen All at Once
The entire permafrost system is unlikely to cross a single global tipping point simultaneously. Instead, scientists are concerned about many local tipping points occurring one after another. Some locations have already experienced irreversible changes, while warming summers and increasingly frequent fires are accelerating thaw in parts of Siberia and Canada. After exceptionally warm summers, researchers have observed new lakes appearing in subsequent years.
This means the Arctic does not need to collapse overnight for the consequences to become serious. The changes can accumulate — landscape by landscape, year by year.
Methane or CO₂? The Landscape Decides
Not all thawing permafrost releases the same gases in the same amounts. If thawed ground becomes dry, microbes can convert carbon from ancient organic material primarily into CO₂. But if the thaw creates wetlands or lakes, oxygen becomes scarce and microbes can produce methane instead. Scientists are still working to determine how much thawing permafrost will become wetter and how much will become drier.
That uncertainty matters because methane is especially powerful over shorter timescales. The supplied research describes methane as roughly 30 times more potent than CO₂ in the short term, while its atmospheric lifetime is much shorter. CO₂, meanwhile, is less powerful molecule-for-molecule but remains in the climate system for much longer. The two gases therefore create different climate pressures – one more immediate, the other enduring.
The Numbers Behind the Warning
The methane research offers a stark illustration of how these two greenhouse gases interact. Under a scenario reaching net-zero CO₂ emissions in 2050, limiting peak warming to 1.7°C would require methane emissions to fall by at least 69% by 2050, compared with 2020 levels.
For a 2050 net-zero target covering all greenhouse gases, the required methane reduction would be 63%. But current policies point in the opposite direction. Methane emissions are expected to rise by around 20% by 2050 compared with 2020.
The study finds that such a pathway could produce peak warming above 2°C by 2050 even if global CO₂ emissions reached net zero. Cutting methane by roughly one-third, consistent with the Global Methane Pledge’s 2030 target, could lower peak warming by around 0.15°C, with approximately 0.05°C of that reduction potentially achievable through interventions with no net cost.
A Carbon Budget Under Pressure
There is another reason methane matters. The world has a finite carbon budget – the cumulative amount of CO₂ that can be emitted while keeping warming below a chosen threshold. Estimates cited in the research put the remaining carbon budget for a 2°C limit at roughly 1,000–1,150 gigatons of CO₂ as of 2025, assuming substantial methane reductions.
If methane emissions are not reduced, the remaining budget becomes smaller. Under the study’s analysis, if methane emissions were not cut at all in the future, the remaining carbon budget for limiting warming to 1.7°C would effectively already be exhausted.
The Arctic’s Delayed Warning
Perhaps one of the most unsettling aspects of permafrost thaw is that the climate system does not respond instantly. There can be a decades-long time lag between atmospheric warming and the full thawing response of permafrost. Vegetation and thick layers of peat can insulate the frozen ground and delay the effects.
That means some future thaw is already locked in because previous warming has pushed certain regions beyond their thresholds. Yet the picture is not entirely predetermined. The research indicates that limiting future warming could prevent large areas of Siberian and Canadian permafrost from thawing.
Wildfires Add Fuel to the Threat
Heatwaves and wildfires are making the situation more dangerous. Professor Hugelius describes increasing evidence of rapid permafrost thaw since his fieldwork in the Russian Arctic began in 2007. Warmer summers and stronger fires in Siberia and Canada can interact to accelerate the thawing process.
The consequences could be enormous. The analysis cited in the source estimates that if global temperatures reach between 1.8°C and 3.6°C of warming by the end of the century, around 200–300 gigatons of CO₂ equivalent could be released from permafrost. In even higher-warming scenarios, the amount could approach today’s annual emissions of major economies.
The Ground Beneath the Arctic Is Changing
Permafrost thaw is also an economic and infrastructure problem. As frozen ground becomes unstable, roads, buildings and industrial infrastructure can be damaged. Resource extraction can become more difficult and expensive, while the instability of Arctic landscapes creates additional challenges for communities and industries.
The climate threat therefore extends far beyond the release of greenhouse gases. A changing Arctic can become a changing economic landscape.
There Is Still a Way to Slow the Feedback
Scientists cannot simply refreeze millions of square kilometres of thawing permafrost through a large-scale technological fix. The central solution remains reducing greenhouse-gas emissions rapidly. Professor Hugelius estimates that for every degree of global warming avoided, around 4 million square kilometres of permafrost could be protected from thawing and associated greenhouse-gas release.
That makes every fraction of a degree important. It also makes methane impossible to treat as a side issue.
The Climate Clock Is Ticking in Two Directions
The climate challenge is often described as a race to cut CO₂. But the science presented here tells a more complicated story. We have to cut CO₂ because it accumulates and persists. We have to cut methane because it drives powerful near-term warming. And we have to slow warming before it unlocks additional greenhouse gases from natural systems such as permafrost.
The danger is not simply that humanity adds more greenhouse gases to the atmosphere. It is that a warming planet can begin to release some of its own stored carbon. Permafrost is one of the clearest examples of this risk.
Scientists are confident that substantial amounts of CO₂ and/or methane will be released as permafrost thaws. What remains less certain is the precise speed of the process and whether individual regions will become wetter or drier — factors that influence whether more methane or CO₂ is released.
That uncertainty is not a reason to wait. It is a reason to understand the risk. Because beneath the frozen Arctic lies an ancient carbon store — and the warmer the planet becomes, the more of that frozen past could be released into the atmosphere. The climate crisis is no longer only about what humanity puts into the air. It is increasingly about what a warming Earth may begin to release on its own.
