Warming in the Arctic is greater than elsewhere in the world. Wildlife experts believe that the warming is a main reason that most herds of caribou (reindeer), like these in Alaska, have recently declined in numbers. This abundant and prolific species is expected to persist. But even they will be at risk of extinction (along with polar bears and many others) if greenhouse gas emissions continue to grow uncontrolled to the end of this century and beyond.

Global warming is also measurably damaging alpine meadows like this one in Wyoming, coral reefs like the rapidly deteriorating Great Barrier Reef of Australia (below), and other important ecosystems. They will be devastated within our lifetime — along with many equally vulnerable human communities — unless prompt action is taken.