What is permafrost thawing?

The water that is trapped in sediment, soil, and the cracks, crevices, and pores of rocks turns to ice when ground temperatures drop below 32°F (0°C).

When the earth remains frozen for at least two consecutive years, it’s called permafrost. If the ground freezes and thaws every year, it’s considered “seasonally frozen.”

About a quarter of the entire northern hemisphere is permafrost, where the ground is frozen year-round.

It’s widespread in the Arctic regions of Siberia, Canada, Greenland, and Alaska—where nearly 85 percent of the state sits atop a layer of permafrost.

It’s also found on the Tibetan plateau, in high-altitude regions like the Rocky Mountains, and on the floor of the Arctic Ocean as undersea permafrost.

In the southern hemisphere, where there’s far less ground to freeze, permafrost is found in mountainous regions such as the South American Andes and New Zealand’s Southern Alps, as well as below Antarctica.

Permafrost is any type of ground, from soil to sediment to rock—that has been frozen continuously for a minimum of two years and as many as hundreds of thousands of years. It can extend down beneath the earth’s surface from a few feet to more than a mile—covering entire regions, such as the Arctic tundra, or a single, isolated spot, such as a mountaintop of alpine permafrost.

Impact of permafrost thawing

Huge Carbon Sink: An estimated 1,400 gigatons of carbon are frozen in Arctic permafrost, making it one of the world’s largest carbon sinks.

That’s about four times more than humans have emitted since the Industrial Revolution, and nearly twice as much as is currently contained in the atmosphere.

According to a recent report,2 degrees Celsius increase in temperature, expected by the end of the century will result in a loss of about 40 percent of the world’s permafrost by 2100.

Loss of trapped Greenhouse gases: Packed with many thousands of years of life, from human bodies to the bodies of woolly mammoths, permafrost is one of the earth’s great stores of global warming gases.

Indeed, permafrost in the Arctic alone is estimated to hold nearly twice as much carbon as exists in the atmosphere now, as well as a sizable amount of methane—a powerful greenhouse gas that traps more than 80 times more heat on the planet than carbon does.

Toxins: A recent study found that Arctic permafrost is a massive repository of natural mercury, a potent neurotoxin. Indeed, it’s estimated that some 15 million gallons of mercury—or nearly twice the amount of mercury found in the ocean, atmosphere, and all other soils combined—are locked in permafrost soils.

Once released, however, that mercury can spread through water or air into ecosystems and potentially even food supplies.

Crumbling Infrastructure: About 35 million people live in a permafrost zone, in towns and cities built on top of what was once considered permanently frozen ground.

But as that solid ground softens, the infrastructure these communities rely on grows increasingly unstable.

Eg: Recent Russian Norilsk diesel oil spill is an ongoing industrial disaster, which occurred at a thermal power plant that was supported on permafrost, crumbled.

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