Catalyst: Geoengineering - a solution to climate change?

DR GRAHAM PHILLIPS:

Our planet's climate is a highly complex, interlocked, self-organising system. It's been under nature's control for aeons. Could we intervene and take over some of the control? Well, advocates of geoengineering believe we could. Geoengineering is the deliberate engineering of the climate to combat some of the effects of climate change. For example, one suggestion is to release a whole lot of sulfate particles into the sky. It's like fighting pollution with pollution. Just as carbon emissions warm things up on Earth, the sulfate particles should cool things down. It sounds completely crazy, but here in London geoengineering has taken on a new credibility. Its ideas have been seriously investigated by no less than the Royal Society. The Royal Society is a collection of some of the world's top scientists. In fact, it's considered a real honour to become a member. The organisation has been going since 1660. This is the famous report.

PROFESSOR JO HAIGH:

That's right. This is Geoengineering The Climate that the Royal Society commissioned.

DR GRAHAM PHILLIPS:

It's pretty controversial stuff, geoengineering.

PROFESSOR JO HAIGH:

It is, but it's risen up the political agenda to such an extent that I think it's not sensible to pretend that it doesn't exist. The thing to do is try and look at it objectively and see the pros and cons and have a scientific perspective on the whole thing.

DR GRAHAM PHILLIPS:

There's a whole host of ideas, from the very sci-fi - cooling the Earth by constructing giant sunshades in space - to adding iron to the oceans as fertiliser. Fertilising the oceans means putting certain nutrients in the sea to help algae grow. And just as when trees grow on land, when the algae grow they suck carbon dioxide out of the atmosphere, thus reducing our carbon emissions.

PROFESSOR JO HAIGH:

That works. The trouble is you might also be poisoning the oceans by putting in these extra things. And we need to think about what is the side effects of these mechanisms?

DR GRAHAM PHILLIPS:

Remarkably, one of the more serious ideas is putting sulfate particles into the sky.

PROFESSOR JO HAIGH:

When big volcanoes erupt they emit particles, and when it's a very big eruption these particles sit in the stratosphere for months, if not years, and there has been a measured cooling in response to volcanic eruptions. The idea would be to essentially simulate those volcanic eruptions by putting sulfate particles into the stratosphere and reflect the sun's radiation back to space.

DR GRAHAM PHILLIPS:

The particles could be released from airborne craft, just as today planes release silver iodide particles into clouds to try to seed rain. If cost were no object, it could be done, but there'd be a few consequences.

PROFESSOR JO HAIGH:

It almost certainly would destroy ozone. And we've seen ozone depletion is response to volcanic eruptions.

DR GRAHAM PHILLIPS:

And the world might be cooler, but what would happen to the weather?

PROFESSOR JO HAIGH:

You don't get the whole of the climate back to what it was before. So there are large changes in the monsoon patterns, for example, a tropical rainfall. And the whole of the hydrological cycle, which, therefore, of course, affects the tropics in a very significant way. And you have to be careful that you're not tweaking one part of the climate system without knowing what's happening to the rest.