Just centimeters below the Earth’s surface is a ticking time bomb that could detonate as global temperatures rise. It's called permafrost.
Permafrost is found at high altitudes in mountains such as the Himalayas, the Andes and the Southern Alps of New Zealand, as well as at the poles in Antarctica and, especially, in the Arctic.
Permafrost is a lot like concrete. In permafrost, ice binds together soil, rocks, sand and organic matter. Some of that organic matter includes the remains of plants and animals that have been frozen since the last Ice Age, more than 11,000 years ago.
Now, human-induced climate change – caused by the buildup in the atmosphere of greenhouse gas emissions from industrial activity, mainly the burning of coal, oil and natural gas - is raising global temperatures and driving heat waves that can cause permafrost to thaw. And as permafrost thaws, the organic matter locked within it is starting to decompose, a process that releases even more climate-warming carbon dioxide and methane into the atmosphere.