Roughly 15,000 years ago, at the end of the last ice age, North America's vast assemblage of large animals — including such iconic creatures as mammoths, mastodons, camels, horses, ground sloths and giant beavers — began their precipitous slide to extinction.

Some climates may disappear from Earth entirely, not just from their current locations, while new climates could develop if the planet continues to warm, a study says.