Al Gore on Tuesday compared the battle against climate change with the struggle against the Nazis.
The former vice president said the world lacked the political will to act and invoked the spirit of Winston Churchill by encouraging leaders to unite their nations to fight climate change.
He also accused politicians around the world of exploiting ignorance about the dangers of global warming to avoid difficult decisions.
Speaking at Britain's Oxford University at the Smith School World Forum on Enterprise and the Environment, sponsored by the Times of London, Gore said, "Winston Churchill aroused this nation in heroic fashion to save civilization in World War II."
He added, "We have everything we need except political will, but political will is a renewable resource."
Gore admitted that it was difficult to persuade the public that the threat from climate change was as urgent as the threat from Nazi Germany.