After a massive gaping crater was discovered in the permafrost of the Yamal peninsula in Siberia—and a boatload of theories were formed about how it got there, ranging from meteorite collisions to UFO invasions—scientists have come up with a more plausible theory: global warming. Though more research needs to be done before a conclusion can be drawn, geologists are zeroing in on the possibility that the hole was formed by a pingo. Pingoes are blocks of ice that form in hills in arctic ground. Eventually, the ice can push through to the surface and melt away, leaving an exposed crater. “We’re seeing much more activity in permafrost areas than we’ve seen in the historical past. A lot of this relates to this high degree of warming around these high arctic areas which are experiencing some of the highest rates of warming on earth,” an Australian polar scientist said.