4. Yamal Peninsula, Russia

Yamal Peninsula, Russia  [huanqiu.com]

A large amount of reindeers roam in northern Siberia, where the subsoil is permanently frozen. In Yamal, 300,000 wild reindeer have adapted to the inclement Siberian winters.

If global warming continues over the next century as predicted, more trees could spread to the tundra. This may thaw the permafrost and make the ground too muddy for the reindeer herds to cross.