New Study Warns Arctic Permafrost Could Become a Major Carbon Source Earlier Than Expected

The Arctic has long been regarded as one of the world's most important climate warning systems. It is where rising global temperatures are amplified, where sea ice retreats at record pace, and where vast stretches of permanently frozen ground are beginning to thaw.

Now, a new study published in Science Advances suggests another worrying milestone may arrive earlier than previously expected: the point at which Arctic permafrost regions release more carbon dioxide into the atmosphere than they absorb.

The finding adds to a growing body of evidence that climate change in the Arctic is advancing faster than scientists anticipated only a decade ago.

Permafrost soils contain enormous quantities of organic carbon accumulated over thousands of years from dead plants and other biological material that never fully decomposed because the ground remained frozen. Collectively, Arctic permafrost stores roughly twice as much carbon as is currently found in the atmosphere.

As long as those soils remain frozen, much of that carbon stays locked away. But when permafrost thaws, microbes begin breaking down the organic material, releasing carbon dioxide and methane into the atmosphere. This creates what scientists call a "feedback loop": warming causes thawing, thawing releases greenhouse gases, and those emissions contribute to additional warming.

The new research suggests that many climate models may underestimate how quickly this process could accelerate.

The reason lies deep underground.

Many Earth system models focus primarily on carbon stored in upper soil layers. The researchers behind the new study incorporated much larger and deeper permafrost carbon reservoirs into their simulations and found that these previously underrepresented carbon stores could significantly increase future emissions from thawing Arctic soils.

As a result, northern permafrost regions could shift from acting as a net carbon sink, absorbing more carbon than they release, to becoming a net source of emissions earlier this century under high-emissions scenarios.

While scientists have long expected such a transition eventually, the study suggests the timetable may be shorter than previously thought.

Upward revisions

The findings fit into a broader trend that has characterized Arctic climate research in recent years: repeated upward revisions of how rapidly the region is changing.

For years, the Arctic was commonly described as warming roughly twice as fast as the global average. More recent research pushed that estimate to around three times the global rate. By the early 2020s, several studies concluded that the Arctic was warming closer to four times faster than the planet as a whole, a phenomenon known as Arctic amplification.

This accelerated warming has already transformed large parts of the region. Sea ice extent continues to decline, glaciers and the Greenland Ice Sheet are losing mass, coastal erosion is accelerating, and permafrost degradation is increasingly affecting infrastructure, ecosystems and communities across the North.

Arctic as a climate driver

The new study highlights another consequence that is less visible but potentially global in its significance.

Unlike sea ice loss, which primarily affects how much sunlight the Arctic reflects back into space, permafrost thaw has the potential to directly increase concentrations of greenhouse gases in the atmosphere. Once released, those emissions are extremely difficult to reverse on human timescales.

The study does not suggest that a sudden carbon "bomb" is imminent. Rather, it points to a gradual but increasingly significant source of emissions that could make achieving international climate targets more difficult than current projections assume.

Its broader message is that the Arctic is not merely responding to climate change. It is increasingly becoming a force that can amplify it.

As scientists continue to uncover the scale of carbon locked beneath the North's frozen landscapes, the Arctic's role in shaping the planet's climate future appears larger and more immediate than previously believed.