Four new craters have been discovered in northern Russia, and some fear that global warming is causing gas eruptions from under the Earth's crust, according to U.K.'s Daily Mail.

Three huge craters were discovered in Sibera's Yamal Peninsula last year and more have been spotted - four giant craters and dozens of smaller holes. The holes are believed to be caused by methane gas eruptions. One crater, named B2 by scientists, is located six miles south from a major gas production plant, Gazprom gas field at Bovanenkovo, according to The Siberian Times.

Scientists believe there are probably 30 more craters that haven't been discovered in the peninsula's permafrost. Residents that live near one of the craters by Antipayuta on the peninsula report having seen a flash of light, which reinforces the possibility of gas explosions.

Vasily Bogoyavlensky, deputy director of the Moscow-based Oil and Gas Research Institute, said the investigation of what scientists call "funnels" is "urgent," particularly due to the safety concerns.

"We know now of seven craters in the Arctic area," Bogoyavlensky told The Siberian Times. "Five are directly on the Yamal Peninsula, one in Yamal Autonomous District, and one is on the north of the Krasnoyarsk region, near the Taimyr Peninsula. We have exact locations for only four of them. The other three were spotted by reindeer herders. But I am sure that there are more craters on Yamal, we just need to search for them."

"I would compare this with mushrooms," he continued. "When you find one mushroom, be sure there are few more around. I suppose there could be 20 to 30 craters more."

Bogoyavlensky told The Siberian Times that two of the newly discovered funnels have turned into lakes. "'It is important not to scare people, but this is a very serious problem," he said. "We must research this phenomenon urgently to prevent possible disasters. We cannot rule out new gas emissions in the Arctic and in some cases they can ignite."

Residents living close to another of the craters, close to Antipayuta on the Yamal Peninsula, reported seeing a flash of light.

"We need to answer now the basic questions: what areas, and under what conditions, are the most dangerous? These questions are important for the safe operation of the northern cities and infrastructure of oil and gas complexes," Bogoyavlensky told The Siberian Times.

Some experts believe climate change is affecting the permafrost, which traps one million times more methane hydrates than ordinary gas. The total explosive power of the craters is estimated by one expert to be equivalent to 11 tons of TNT, according to Daily Mail.