A second massive hole in the earth has opened up in Siberia, which some say marks a tipping point in carbon-driven climate shifts.

Reindeer herders were the first to stumble across a large hole, about 30 kilometres from where another was found just weeks before, according to the Moscow Times.

Local politician Mikhail Lapsui says hole No. 2 is “exactly” like hole No. 1, but “much smaller.”

Both chasms appear to have formed quite recently.

Siberian scientists say they have pretty good idea of what is going on.

“Global warming, causing an alarming melt in the ice under the soil, released gas causing an effect like the popping of a Champagne cork,” a news report said, citing an expert at the Subarctic Scientific Research Center.

As permafrost continues to become much less permanent, there is increasing concern that the natural release of methane and other greenhouse gases will accelerate.

Given that Arctic permafrost holds more frozen carbon than currently exists in the entire atmosphere, the risks are clear.

Methane is several times more effective at trapping atmospheric heat than carbon dioxide, and some studies link massive releases of methane to the Earth’s mass extinctions.

There are plenty of challenges in recording levels and increases in Arctic methane, but trying to keep a lid on its methane blow-outs could become a major task in the future.