Permafrost. Break the word down: Perma -- permanent or long-lasting
and frost -- frozen. Permafrost is soil that has been frozen for at least
two years. But typically, it’s been frozen for much longer, hundreds or even thousands of
years. Permafrost is found in the Arctic, the Antarctic, and at high elevations.
So, why do we care about a frozen layer of soil? Because the human-caused
climate change that's warming Earth is warming the Arctic first and fastest. And as
temperatures climb, permafrost thaws. Thawing permafrost is a problem
for things people build. As frozen soil turns to mud and water, roads, runways,
and buildings start to wobble and collapse. And thawing permafrost packs a
double punch by releasing planet-warming greenhouse gases. Over centuries,
ancient plants and animals became frozen in the permafrost, which stored this material like a big
freezer. When permafrost thaws, this organic material is eaten by microorganisms,
releasing carbon dioxide and methane into the atmosphere, adding to the greenhouse
gases released by human activities that thawed permafrost in the first place.