The latest estimate is that some 18.8 million square kilometres of northern soils hold about 1,700 billion tonnes of organic carbon4 — the remains of plants and animals that have been accumulating in the soil over thousands of years. That is about four times more than all the carbon emitted by human activity in modern times and twice as much as is present in the atmosphere now.
The permafrost carbon thus represents a dangerous amplifying feedback or vicious cycle whereby warming leads to accelerated emissions, which leads to further warming. And that could lead to a point of no return, as Gillis reports:
In the minds of most experts, the chief worry is not that the carb"
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