Former US vice president Al Gore issued a sharp wake-up call over global warming at the Cannes Film Festival, warning the earth was facing "a planetary emergency." Last year's spate of natural disasters such as Hurricane Katrina which devastated New Orleans in August were proof that global warming was beginning to wreak havoc due to global climate change, he said.
"Mother Nature has joined this debate with a very powerful and persuasive voice," Gore told a press conference after a screening of "An Inconvienent Truth," which documents his one-man crusade to raise awareness about the issue.
"Hurricane Katrina was a wake-up call for many people who had heard that the scientists were warning that the hurricanes would get much stronger. These and other phenomenon that have long been predicted are now coming to pass.
"The key to solving this crisis depends upon the people demanding action and not just of a president, but of the Congress as well."
He said he believed a huge opportunity had been lost in the aftermath of the September 2001 terrorist attacks to wean the United States -- the world's largest single producer of C02 gases -- off its dependence on fossil fuels.
"I also believe that after 9/11 if, in addition to rallying the country and wisely invading Afghanistan to pursue Osama bin Laden, that if the president of the United States had said 'Let's become independent of oil and coal', that people would have responded to that."
Since his narrow defeat in the 2000 presidential elections, Gore has criss-crossed the country showing his slide-show to audiences in at least 1,000 places, entreating them to join the fight against global warming.
"I know from my experiences in the past, what I can most valuably do is to try to change the minds of the American people and people elsewhere in the world about this planetary emergency."
Until recently, he said, the people in the US had been living in a bubble of unreality.
"But I believe that as more citizens understand the gravity of this planetary emergency they will be much more forceful in insisting that politicians respond to it," he said.
Saying he was an optimist, he added he believed that even US President George W. Bush and his Vice President Dick Cheney, who have refused to ratify the Kyoto Treaty which Gore helped negotiate aimed at reducing greenhouse gases, would be forced to change their minds.
"One can only attempt to create one's own reality for so long. Reality proper has a way of insisting itself upon you."
Things would change when people began to realize that the planet stood at a crossroads and in "one direction lies potentially the end of human civilisation and point of no return beyond which the planet's climate system degrades, and in the other direction lies hope and opportunity."
"When that fundamental choice is understood clearly, you will see a shifting toward a dramatic response, and those politicians in whatever party who want to be left behind, will be left behind and will be out of office," he said.
"An Inconvienent Truth," directed by Davis Guggenheim, is not appearing in the competition part of the Cannes Film Festival.
