To cool Earth, just scrub the carbon

Most efforts to halt global warming involve cutting emissions of carbon dioxide – the most significant greenhouse gas produced by humans. But what if we could help stabilize the climate by somehow removing the CO2 that's already in the air?

That's exactly what Sir Richard Branson wants to do. On Friday, the British billionaire announced in London the Virgin Earth Challenge, a competition offering $25 million to whoever can come up with a way to scrub at least 1 billion tons of CO2 a year from Earth's atmosphere. Worldwide, the burning of fossil fuels releases about 25 billion tons of CO2 annually.

The project is backed by some of the top names in climate advocacy. Along with Mr. Branson, the panel of judges will include former Vice President Al Gore; NASA's chief climatologist Jim Hansen, one of the first scientists to predict global warming; and British scientist James Lovelock, who first proposed the Gaia Theory, which likens the Earth to a single living organism. Also on the panel are British environmentalist Crispin Tickell and Australian biologist Tim Flannery.

Branson said that he drew inspiration from an 18th-century British competition. In 1714, an act of Parliament offered 20,000 pounds – a huge sum at the time – to anyone who could accurately calculate longitude. In 1773, the prize went to John Harrison, a working-class clockmaker.

More recently, the Ansari X Prize offered $10 million for a manned spacecraft that could fly into space at least twice in two weeks. In 2004, it went to aerospace designer Burt Rutan and financier Paul Allen. That year, Branson signed a deal with the pair to license the technology for space tourism with Virgin Galactic, whose first flight is planned for 2009.

This venture – an attempt to create a space-tourism market where none yet exists – has prompted accusations of hypocrisy. In an Op-Ed in The Independent, a British daily, Steve Connor notes the huge amount of fuel needed to send a person into space, along with Branson's stated desire to make spaceflight less exclusive:

"The prize he is announcing today to capture and store man-made CO2 is a commendable gesture.... But how does he square that with his desire to turn us all into an army of carbon-crazed space cadets?"

And the Virgin founder's fleet of carbon-spewing airplanes has not gone unnoticed. The Financial Times writes:

"[E]nvironmental groups pointed to the irony of such an offer from the owner of an airline.... Tony Juniper, director of Friends of the Earth, said: 'He appears deeply confused about climate change. The harsh reality is that companies like his can't continue to pollute at the level they are doing.' "

The Guardian quotes Kevin Anderson, a top climate researcher, who is skeptical of what he calls "hopeful, madcap magic-bullet schemes":

"He's misguided, misinformed and potentially quite dangerous in making people think there is some great technological hope out there.... He should rethink his attitude to rail and aviation rather than take this wacko, futuristic route."

Branson has endeavored to make his transportation holdings more ecofriendly. Last October, he announced that all profits from his air and rail interests – an estimated $3 billion – would be reinvested to develop a "clean fuel."

Critics of this reinvestment have observed that, for these companies to profit, they must produce even more carbon emissions. Further, experts say that clean alternatives to jet fuel are decades away.

As for Virgin Galactic, the company's website claims that the spacecraft will be "many times more environmentally friendly" than those of other space programs, but it doesn't elaborate.

Branson isn't the first billionaire to back attempts to remove greenhouse gases from the atmosphere. Gary Comer, the late founder of the Lands' End mail-order retailer, teamed up with Columbia University geologist Wallace Broeker to develop technologies that suck up CO2 and bury it.

But can we remove enough CO2 to have an impact? Maybe. In 2003, a Columbia University physicist proposed planting 250,000 giant paddles coated with carbon-absorbing chemicals around the globe, but added that more research was needed. And in 2004, US researchers observed that seeding the ocean off the coast of Antarctica with iron creates a massive phytoplankton bloom that absorbs carbon dioxide.

It could be many years before greenhouse-gas removal technology is proven: the Virgin challenge plans to test the program for a decade before paying out the prize money. Until then, we'll have to be content with the slow, yet reliable, CO2 scrubbers that have been around all along: plants.