Richard Branson, left, and former U.S. vice-president Al Gore hold a globe at a presentation in London on Friday to announce the Virgin Earth Challenge. ((Kirsty Wigglesworth/Associated Press))

British airline tycoon Richard Branson announced a $25-million prizefor the first person or group to find a way to remove billions of tonnes of greenhouse gases from the atmosphere.

Flanked by former U.S. vice-president Al Gore and leading environmentalists, the Virgin Group chair saidon Friday in Londonhe hoped the prize would spur innovation toward solving what he sees as a crisis.

The contest, called the Virgin Earth Challenge, will be open for five years, with a panel of judges including Branson and Gore evaluating submissions.

The goal is to find a way of removing one billion tonnes of carbon gases a year from the atmosphere for 10 years. The winner will receive $5 million US up front and the remaining $20 million after the 10-year time frame. If no winner is identified after five years the judges may decide to extend the competition.

"The Earth cannot wait 60 years. We need everybody capable of discovering an answer to put their minds to it today," Branson said.

Gore, whose global warming documentary An Inconvenient Truth helped direct public attention to the issue, said the planet had a "fever" that had to be taken seriously.

"Up until now, what has not been asked seriously on a systematic basis is, is there some way that some of that extra carbon dioxide may be scavenged effectively out of the atmosphere? And no one knows the answer to that," Gore said.

The announcement of the contest comes a week after an Intergovernmental Panel on Climate Change report from the world's top scientists predicted global temperatures would increase by between 1.8 andfour degrees this century.

The report said it was very likely these rises in temperature were due to human activities such as the burning of fossil fuels.

With files from the Associated Press