A gaping—and growing—hole in the middle of a Siberian forest isn't the gateway to the underworld, as some frightened locals believe. It may be worse. The Batagaika crater, the biggest megaslump on Earth, may be be a "harbinger" of our warming planet, as Motherboard puts it.

The crater, located in one of the planet's coldest places, appeared about 25 years ago, and geologist Julian Murton of the University of Sussex tells the Independent that it was likely born after locals cut down a swath of forest that sat above the permafrost.

"Cutting down of vegetation ... removes some of the insulation that keeps the ground cool," he explains, and that allows the summer's heat to reach deeper levels of earth.

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As exposed ice layers melt, the earth becomes loose and literally slumps. The chasm has grown to be a mile long and some 400 feet deep, and it continues to grow at a rate of more than 60 feet per year.

More worrisome, the melting permafrost releases large amounts of the potent greenhouse gas methane, which had previously been locked in the soil. This triggers a "climate feedback loop," explains MNN: A warming planet's impact on the permafrost puts methane in the air, which promotes further warming, and the cycle is "difficult to stop," per the site.

And were the entire permafrost to melt, the Independent reports "it would likely tip the planet into an extreme scenario the full horror of which is hard to describe." As such, MNN reports that researchers view megaslumps as a threat to the planet's health, "an omen, a symptom, of a larger underlying disease." (Read how the "Gates of Hell" emerged in a Soviet desert.)

This article originally appeared on Newser: 'Gateway to the Underworld' May Be Something Worse