For hundreds of thousands of years, the Siberian permafrost has been a giant freezer for everything buried within it. But global warming has put the frozen ground in defrost mode, and the tundra is now heating up twice as fast as the rest of the planet. “Permafrost is a silent ticking time bomb,” says Robert Spencer, an environmental scientist at Florida State University. As it thaws, the dirt could release a litany of horrors. Beware: The ice-beasts cometh. Read more.