Original URL: http://www.theregister.co.uk/2008/05/23/sunshade_world_lukewarm/

Climate profs 'can't recommend' enormo-space-parasol

Global-warming brains lukewarm on 'Sunshade World' ploy

By Lewis Page

Posted in Science, 23rd May 2008 11:16 GMT

Bristol-based researchers have said that they "can't recommend" the idea of solving global warming by putting a giant sunshade in space so as to cool the earth down.

In their report Sunshade World, Professor Paul Valdes and Dr Dan Lunt of Bristol Uni's School of Geographical Sciences - with colleagues - examine the likely results of artificially reducing the amount of sunlight reaching the Earth. The scientists say that previous studies have estimated that space-based architecture could perhaps achieve this in around 25 years' time, at a cost of "several trillion dollars".

According to a Bristol Uni statement, when compared to scenarios involving "uncontrolled" future climate change, the predicted shifts for a future high-carbon parasol-equipped Earth are relatively small. "In this respect," according to the climate brains, "the research found sunshade geoengineering to be highly successful".

Nonetheless, the sunshade climate model still showed potential problems.

"We found significant cooling of the Tropics, a warming of the polar regions and related sea ice reduction,” said Lunt. "We also found important differences in the hydrological cycle, with Sunshade World being generally drier than the pre-industrial ‘natural’ world. Average precipitation decreased by five percent with the largest decreases being in the Tropics."

Overall, however, the scientists seemed to imply that most of the severe catastrophes foretold in a runaway carbon-driven warming scenario would be greatly reduced by a massive space sun-brolly. Still, the Bristol climate scientists thought it was a bad idea:

Other problems, however, remain unsolved by this form of geoengineering. In particular, the potential effects of ocean acidification on certain types of plankton – the base of the ocean food chain – could lead to an unforeseen impact on ecosystems in Sunshade World.

As a result, the team could not recommend sunshade geoengineering as an alternative to the reduction of carbon emissions.

That's not altogether a surprise, as we can assume Professor Valdes for one was already firmly committed to pushing for carbon-emissions reduction. He is a non-executive director at Greenstone Carbon Management, a consultancy advising businesses on how to reduce their carbon emissions. Valdes' colleagues on the Greenstone board include the well-known Dr Kevin Anderson of the Tyndall Centre at the University of Manchester, whose views on energy are well known - everyone should simply use less, in particular by not leaving their TVs on standby.

Greenstone also appears to endorse biofuels as a viable carbon-reducing plan. Funnily enough, one of the company's co-founders is biofuels biz kingpin Andrew Stone, also a director of Grainfarmers UK - a company which would naturally love to see increased takeup of crop biofuels.

A space-based global sunshade is a pretty wacky idea, no doubt about it. But it isn't really a lot more wacky in many people's view than trying to run the world on food-crop biofuels. And a space sunshade makes a great deal more sense than worrying about TVs on standby - certainly if those TVs are in houses which also contain baths, cookers, irons, washing machines etc. (Seriously: Anderson should be advocating that we all stop ironing our clothes if he really means it. An hour's ironing saved equates to keeping the TV off standby for three months.)

All in all, it seems safe to say that Dr Lunt and his boss Prof Valdes will not have started their recent work well-disposed to the idea that we can emit as much carbon as we like and then deal with the consequences using a global space parasol. Nonetheless, Sunshade World appears to offer a far from disastrous prediction.

The notion's possibly a good backup plan to have ready, then, just in case all the governments of the world don't come together in the next few years and massively clamp down on global carbon emissions. (Either that or it's time to look at the Futurama wheeze of dropping a big ice cube from space into the sea every year, anyway.)

Read all about it from Bristol Uni here (includes paper reference). ®