LONDON — Sir Richard Branson on Friday announced a US$25 million prize for the scientist who comes up with a way to extract greenhouse gases from the atmosphere, comparing it to the 17th-century quest to revolutionize navigation by determining longitude.

The Virgin Group chairman was joined by former Vice President Al Gore and other leading environmentalists as he announced the challenge to find the world's first viable design to capture and remove carbon dioxide from the air.

A landmark report by the world's leading climate scientists and government officials, published in Paris last week, warned global warming will continue for centuries, creating a far different planet in 100 years.

"Man created the problem, therefore man should solve the problem," Branson said. "Could it be possible to find someone on Earth who could devise a way of removing the lethal amount of CO2 from the Earth's atmosphere?"

Branson compared it to a competition launched in 1675 to devise a method of estimating longitude accurately. It was 60 years before English clock maker John Harrison discovered an accurate method and received his prize from King George III.

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

He said many remain skeptical about the reality of climate change.

"The plot is often that no one believes the threat until it is almost too late and then the superhero steps in to save the day," he said. "Well, today we have a threat, we still have to convince many people that the threat is indeed urgent and real. We have no superhero, we have only our ingenuity to fall back on."

Gore said the planet now had a "fever" and the world had to listen to experts.

He said last week's report offered conclusive evidence the planet was unwell. The Intergovernmental Panel on Climate Change said last week that temperatures on Earth could increase by 4.35 Fahrenheit
 degrees by the year 2100.

"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.

Branson, whose business interests include Virgin Atlantic airline and Virgin Trains, rejected charges that it was hypocritical for him to sponsor the prize. He reiterated a commitment made in September to invest $3 billion toward fighting global warming, saying he would commit all profits from his travel companies over the next 10 years.

As part of that pledge, he launched a new Virgin Fuels business, which is to invest up to $400 million in green energy projects over the next three years.

Experts agreed the challenge is difficult, saying no carbon capturing technology exists. Scientists in Scandinavia have started to safely bury CO2 emissions before they reach the atmosphere, but no one has captured them after they are released.

"I see no evidence that a quantifiably acceptable solution or pathway has been identified," said Jerry Mahlman, the former head of climate modeling at the United States' National Oceanic and Atmospheric Association. "It's not what you say, it's what you can do and at the moment you can't do a lot."

The organizers of the "Virgin Challenge" said the winner would receive $5 million once judges rule they have succeeded. The rest of the money will be paid out over 10 years if the judges decide the goal of removing significant amounts of greenhouses gases has been met over the long term.