Stand on the tundra in Alaska and it looks like nothing special.
A vast, flat plain of amber grass, shallow ponds, and dark soil stretching to the horizon.
No obvious drama, no visible crisis.
But a few feet below your boots, something has been building for millennia, and scientists have finally put a dollar figure on what happens when it wakes up.
The ground beneath the Arctic has been keeping a secret for millions of years
Permafrost is frozen ground, soil and rock locked in ice for thousands of years across Alaska, Canada, Siberia, and the high Arctic.
It covers roughly a quarter of the land in the Northern Hemisphere.
Most Americans have never thought about it for a single second.
Permafrost contains about 1,700 gigatons of carbon in the form of frozen organic matter, accumulated over countless millennia of dead plants and animals that never fully decomposed.
That is roughly twice the carbon currently in the entire atmosphere above us.
Think of it as a freezer the size of a continent, stocked with centuries of biological material that simply never had the chance to rot.
For as long as the ground stayed frozen, that carbon stayed locked away, harmless and invisible.
Something is going wrong with the world’s largest freezer
The Arctic is warming roughly four times faster than the global average.
As the ground softens, the organic matter inside it begins to rot.
Permafrost releases both carbon dioxide and methane as it thaws, through rotting organic matter, collapsing terrain, and waterlogged soils where methane-producing microbes thrive.
That methane detail matters more than most people realize.
Methane is over 80 times more effective than carbon dioxide at trapping heat over a 20-year period.
Wildfires are accelerating the process further, scorching the insulating layer of moss and peat that once kept the frozen ground shielded from summer heat.
And once those gases escape, there is no putting them back.
The tundra is already changing in ways you can see from the ground
Across Alaska, roads are buckling and tilting where the ground beneath them has shifted.
Strange new lakes are appearing on the tundra, formed as the frozen ground collapses inward.
Scientists call these thermokarst lakes, and they are spreading.
In some Alaskan villages, houses are sinking and cracking as if the earth beneath them is slowly giving way.
Wooden boardwalks that once crossed stable ground now lean at odd angles, and in a handful of communities, entire buildings have been condemned.
This is not a future warning, it is already happening across the far north.
A study on permafrost and the remaining carbon budget found that including permafrost thaw in climate models meaningfully reduces the allowable carbon budget for avoiding dangerous warming targets.
Scientists ran the numbers and the total came out to $43 trillion
Greenhouse gas emissions from thawing Arctic permafrost could result in an additional $43 trillion in economic impacts by the end of the twenty-second century, according to research from the University of Cambridge and the National Snow and Ice Data Center.
That figure is not the cost of fixing permafrost.
It is the added damage thawing permafrost would layer on top of every other climate cost humans are already calculating.
To put it in scale: the University of Cambridge researchers note that the $43 trillion comes on top of more than $300 trillion in climate-change costs already projected by existing models, meaning permafrost alone could add roughly 13 percent to the total bill.
The NOAA summary of the research makes clear that most existing climate models do not yet fully account for this feedback loop.
A more recent analysis by Woodwell Climate Research Center sharpens that picture further, finding that abrupt thaw and Arctic wildfires together shrink the remaining carbon budget faster than gradual models predict.
The frozen ground was never just scenery, it was a climate vault, and it is now unlocking.
There is still time to slow the key that is turning in the lock
The picture is serious, but it is not hopeless.
Thawing is projected to affect 50 percent of near-surface permafrost at 1.5 to 2 degrees of warming, and up to 90 percent at 3 to 5 degrees.
That gap between those two numbers is the reason every fraction of a degree still matters enormously.
Scientists studying how the 2023 heat record overshot predictions are applying the same urgency to permafrost feedback, working to get these carbon costs into the models governments actually use.
Research teams are experimenting with methods to actively protect permafrost, from restoring grasslands that insulate the frozen layer to tracking thaw rates using satellites.
In places like Juneau, where a glacier burst open for the third summer in a row, residents are already living inside the feedback loops science is still racing to measure.
The ordinary-looking ground beneath the Arctic tundra turned out to be one of the most consequential things on Earth.
And the price of ignoring it was frozen in plain sight all along.