Permafrost, the frozen layer of soil beneath about 15% of land in the Northern Hemisphere, is a major blind spot in climate change science. Most of today's permafrost formed during the last ice age, meaning it has locked away organic material for thousands of years. As global temperatures rise, this layer thaws, allowing microbes to break down that organic matter and release carbon dioxide and methane, powerful greenhouse gases that accelerate warming in a feedback loop. Since 1850, the Arctic permafrost footprint has shrunk by about 12%, and the pace has picked up over the last 50 years.
Yet only a minority of the models used in UN climate reports account for the gradual loss of permafrost, and none include the abrupt thaw and collapse that can follow heat waves and fires. As a result, researchers warn that the planet's warming may be underestimated. Efforts are underway to make future UN reports reflect the growing science.
Wildfires are another accelerant. Although fire is a natural part of boreal forest life cycles, climate change is making fires more intense, and they can speed up permafrost thawing. By the end of the century, this effect could release the equivalent of 80 billion metric tons of carbon dioxide. Current policy across remote parts of Canada and Alaska generally lets wildfires burn unless they threaten human settlements, but some researchers argue that fighting certain fires could save carbon stored in forests and permafrost.
The carbon cycle of permafrost is also highly complicated. Roughly 1.5 trillion tons of carbon are locked in permafrost, about twice the amount in the atmosphere. While thawing can release greenhouse gases, the process involves complex interactions that scientists are still working to understand.
Source: MIT Technology Review · Summarized by HeadlinesBriefing