IT IS madness. It must be. What sense can it make to spray the stratosphere with tiny, shiny balloons to reflect the sun鈥檚 rays, or to open a giant parasol in space between Earth and the sun? And all to curb global warming.
Wouldn鈥檛 we do better to stop the problem at source by the more prosaic methods of improving energy efficiency and boosting renewable energy sources? Most people would think so. Yet the normally level-headed climate scientists trying to persuade politicians to curb greenhouse gas emissions are starting to talk about the need for something extra. They want research, at least, into grand plans for fixing the planet to cope with our pollution, rather than fixing the pollution itself (see 鈥淎 mirror to cool the world鈥�). This sounds dangerous, so what is going on?
One factor is the political opposition, especially in the White House, to cutting carbon emissions. It is making some climate scientists ever more nervous about the planet鈥檚 prognosis. Their gloom is deepened by growing evidence that when climate change comes it will be faster and nastier than previously forecast (see New 杏吧原创, 22 November 2003, p 40). The next report by the UN鈥檚 Intergovernmental Panel on Climate Change, due in a couple of years, is expected to highlight this new thinking. So maybe we need an equally dramatic response: something that can drag us back from the abyss more quickly than is possible simply by curbing greenhouse emissions.
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There is, of course, the danger that if we know we have a safety net, there will be pressure to carry on as we are, especially from conservative politicians who do not want to disturb the industrial status quo. With some of the grand plans, this reasoning may stand up. It may make sense, for example, to encourage fossil-fuel companies to capture and bury their carbon dioxide underground. That, after all, is where they got it from. If done properly, the method could be cheap and low-risk, and carbon buried underground is probably more secure than in carbon-sink 鈥淜yoto forests鈥�.
But plans to launch balloons and mirrors are a different matter. The rationale behind them is that if we cannot instantly stop the atmosphere absorbing more of the sun鈥檚 heat, we should arrange for less solar radiation to reach the atmosphere in the first place. But while these schemes might reduce the temperature, CO2 levels would continue to rise, with potentially unpleasant results. The pH of the oceans would fall, for example, and coral reefs would begin to dissolve. With its chemistry disrupted, the atmosphere could well cease producing the hydroxyl radical that cleanses it of everything from smog to greenhouse gases.
Untried engineering can always go wrong, and with schemes on this scale failure could land us in very deep trouble indeed. We only have one planet. Just how lucky do we feel? Just how mad are we?