Cartoon of the frog and climate change.

The boiling frog is a parable describing a frog being slowly boiled alive. The premise is that if a frog is put suddenly into boiling water, it will jump out, but if the frog is put in tepid water which is then brought to a boil slowly, it will not perceive the danger and will be cooked to death. The inference being that we are all being gradually brought to the boil with climate change.