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While holidaying in the Alps with Lord Byron and Percy Bysshe Shelley, the young Mary Godwin was stranded indoors by unending rain. Stuck for activities to fill the days, she dreamt up a horrific story of a brilliant scientist whose hubris has tragic and unpredictable consequences. She later became Mary Shelley, and the story later became Frankenstein.
We now know that the dreadful weather of 1816 was induced by the vast eruption of Mount Tambora in Indonesia. Two centuries later, the use of imitation volcanic clouds is being seriously contemplated as an antidote to global warming. The word “geoengineering” is on the lips of the world’s atmospheric scientists.
The trigger for the discussion of geoengineering was a 2006 article by Paul Crutzen, a Nobel laureate and expert on the ozone hole. Many scientists share his concern that substantial climate change can no longer be prevented: we are emitting too many greenhouse gases and our plans to stop are tardy and timid.
Geoengineering proposals fall into two broad categories: we can try to remove carbon dioxide from the atmosphere, or we can try to reflect sunlight away to counteract the greenhouse effect that carbon dioxide produces.
Both ideas are superficially tempting. Carbon dioxide lingers for many decades, which means that, even if we stopped pollution tomorrow, warming would continue. Removing carbon dioxide would allow us to undo past harms more quickly and might prevent some tipping point being reached.
Solar radiation management – by creating reflective fluffy clouds to screen the dark oceans, or by using the volcano effect and pumping sulphur particles into the stratosphere – has its own attractions. For one thing, it seems absurdly cheap. So what’s the catch?
The catch is obvious enough. The world’s climate is complicated and we don’t really know what the consequences might be of interfering with it. We can guess at a few: some modelling suggests that a stratospheric sulphur shield could lower global temperatures to where we want them, but would not prevent the oceans acidifying, might affect the monsoon in India, and would cool the tropics while failing to cool the poles.
There are other risks, of course. What if geoengineering becomes a weapon? Clive Hamilton’s otherwise useful book, Earthmasters, is marred by dark mutterings about the connection between geoengineering and Lawrence Livermore National Laboratory, a centre for nuclear weapons research. This doesn’t worry me much. We have far simpler ways to obliterate our enemies.
No, the core case against geoengineering is a radical uncertainty about its consequences. But this cuts both ways. Global warming is a threat not only because of the likely scenario in which the climate changes in harmful ways but we adapt; but in the less likely (but plausible) scenario in which some runaway process makes the planet uninhabitable as we know it. For example: reflective ice melts, exposing dark oceans that absorb heat; warming accelerates; methane is released from the melting tundra; methane exacerbates the greenhouse effect; repeat.
While it would be irresponsible to rely on geoengineering to get us out of our present fix, it would also be irresponsible to turn our backs on the possibility that it might one day prevent catastrophe. Geoengineering experiments are, in any case, already happening – and they are cheap enough for a rogue nation or even a rogue Bond villain to have a go at something quite ambitious. It is time to start thinking about this, and quickly. As Mary Godwin realised, science plus overconfidence can produce an awful mess.
Tim Harford is the presenter of Radio 4’s ‘More or Less’
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