What Are Tundras? | National Geographic

What are tundras? Tundras are among the Earth's coldest and harshest biomes. These ecosystems are treeless regions with extreme cold and low rainfall.

There are two different types of tundras: alpine and arctic. Alpine tundras occur on mountains where trees cannot grow in the high altitudes. There, the growing season is about 180 days. Mountain goats, sheep, marmots, and birds feed on low-lying plants and insects.

Arctic tundra extends from the edge of the Arctic Ocean down to the coniferous forest of the taiga. Permafrost prevents trees from taking root, but shrubs and other vegetation grow during the short summers, which range from 50 to 60 days. A variety of wildlife, including arctic foxes, polar bears, and caribou, live in the arctic tundra.

Global warming is changing the arctic tundra, and the changing tundra is contributing to global warming. The Arctic's permafrost is deteriorating, which alters not only the landscape but also the plants and animals that can live there.

In addition, permafrost contains about 14% of the Earth's carbon, so as it melts, that carbon is released into the atmosphere, contributing to global warming.