Permafrost is ground that stays frozen year round; the permafrost in interior Alaska also has massive wedges of actual ice locked within the frozen ground. When that ice melts, the ground surface collapses and forms a sinkhole that can fill with water. Thus, a thermokarst lake is born. At first glance, Big Trail looks like any lake. But look closer and there's something disturbing the surface: bubbles.

“The big finding was that we really have something that’s coming out from a deep pool,” said Steinbach. As the permafrost thaws, it opens up new pathways that allow methane to pass through.

Today, the fault measures around a kilometer in length, 800 meters in width and 100 meters in depth, making it the largest permafrost thermokarst sinkhole in the world. Its shape is reminiscent of a gigantic mollusc with a tail.

The ground under the new road is developing a sink hole and affecting the foundation of the adjacent house.

Russian scientists in the Arctic Ocean said they have discovered the most powerful methane gas fountain ever recorded, highlighting the danger of this greenhouse gas accelerating climate change or causing an oil or gas spill as it erupts from thawing permafrost.

“It’s an area that I and some other colleagues have started thinking about: can you get methane forming in terrestrial environments? But it’s a very new area of science,” carbon scientist Katey Walter Anthony said.

Locals say they saw flames and smoke as a major bubble of methane blasted below the surface and created another sinkhole in the Russian Arctic peninsula.

Detailed study of satellite data has identified more than 200 lakes with active methane emissions.

On a rising tide, a line of bubbles from the mud under the water of Ugashik Bay can be observed rising forcefully to the surface.

Tracking changes in permafrost can take years and sometimes decades, lags that cannot keep up with the transformations in the rapidly warming Arctic.