Former Vice President Al Gore joined British tycoon Sir Richard Branson in announcing a $25 million prize for a process that can extract at least a billion tons of CO2 per year from the atmosphere.

Branson compared the competition to an historical one in 1675 that was launched by King Charles II seeking to devise a method of estimating longitude accurately. The British Parliament offered a prize in 1714 and some 60 later, English clock maker John Harrison collected the prize from King George III for inventing an accurate chronometer.

“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,” said Gore.

Entries will be evaluated by Branson and Gore, as well as NASA climate scientist James Hansen; James Lovelock, who devised the Gaia theory of Earth’s ecosystems; British environmentalist Sir Crispin Tickell; and Australian paleontologist Tim Flannery.

The winner will be the one that establishes a way of removing 1 billion tons of the gas per year for a period of 10 years. A $5 million prize will be paid at the beginning of the project and the remaining $20 million at the end.

Competition details are available to www.virginearth.com.