Creating people's geographies
Bring back the acid rain
A scientist who worked out the ozone problem says pollution could save us from global warming
Thursday August 3, 2006
The atmospheric scientist Paul Crutzen would like to save the world and darken your day. He proposes in this month’s issue of the journal Climatic Change that to screen themselves from runaway global warming, humans could use heavy artillery to lob huge explosive shells laden with sulphate particles high into the stratosphere.A potent mix of pollutants would scatter the incoming sunlight and bounce more sunbeams back into space. Bingo, you’d lower the rate of global warming, make the planet’s current tenants a little bit more secure and give the fossil-fuel industries more reason to push hydrocarbons and fill up the corporate coffers. Then they’d make a second killing marketing fossil fuels’ unwelcome byproducts, all to cancel the extra global warming they might have caused. Stuff that goes into the stratosphere tends to stay there for a year or two, which is why planetary temperatures tend to drop a little after a really big volcanic eruption.
Before anybody goes into a froth of rage, denunciation, or for that matter delight, consider the irony. In half a human lifetime the planet has faced three atmospheric crises. The first was acid rain, caused by sulphate pollution from car exhausts and factory chimneys. The second was the loss of ozone in the stratosphere, caused by the use of chlorofluorocarbons. Crutzen was one of three scientists who shared a Nobel prize in 1995 for working out how this happened. The third is global warming, caused by more carbon dioxide being pumped into the atmosphere as more humans use more fossil fuels.So the scientist who helped solve crisis number two now proposes to limit catastrophe number three by bringing back calamity number one. It would be far more sensible simply to burn less fossil fuel. But, as Crutzen says, given the “grossly disappointing international political response” to the idea that humans should reduce their greenhouse-gas emissions, it might be a good idea to start thinking now about climate engineering against some future emergency.
So he has done the sums. You could compensate for global warming by stuffing huge balloons with sulphate particles and floating them up into the stratosphere before bursting them. Or you could use really big guns to shoot the stuff up. Either way, you’d have to get 2m tonnes of the stuff to an altitude of more than 10 miles, every year. That would cost $25bn-$50bn a year. On the other hand, you’d save an awful lot if sea levels stopped rising, ice caps stopped melting and deserts stopped advancing. You’d only need a trifling fraction of the 55 million tons of sulphates that cars, factory chimneys and aeroplanes produce every year. And if $25bn-$50bn still seems an awful lot of money, remember that the world spends $1,000bn on guns, bombs, rockets, tanks, nuclear submarines and stealth bombers every year.
So don’t think of Crutzen’s proposal as barking mad. Think of it instead as another way of waking up the world to the huge size of the problems ahead. Science is sometimes quite good at tricks like this. A few years ago a Utah scientist calculated that 98 tons of fern, cycad and conifer must have grown in the carboniferous era to turn up again 300m years later as a gallon of petrol. “Can you imagine loading 40 acres’ worth of wheat – stalks, roots and all – into the tank of your car or SUV every 20 miles?” he asked. Crutzen is really asking us to imagine the unimaginable, in the hope that we might wake up to the reality and start reducing carbon emissions.
And if we do end up lobbing vast slag heaps of pollutants into the stratosphere to provide a bit of emergency shelter for the planet, there will be compensatory effects. The skies would become a little whiter, Crutzen warns, “but also colourful sunsets and sunrises would occur”.