snipNobel Prize-winning scientist has drawn up an emergency plan to save the world from global warming, by altering the chemical makeup of Earth's upper atmosphere. Professor Paul Crutzen, who won a Nobel Prize in 1995 for his work on the hole in the ozone layer, believes that political attempts to limit man-made greenhouse gases are so pitiful that a radical contingency plan is needed.
In a polemical scientific essay to be published in the August issue of the journal Climate Change, he says that an "escape route" is needed if global warming begins to run out of control.
Professor Crutzen has proposed a method of artificially cooling the global climate by releasing particles of sulphur in the upper atmosphere, which would reflect sunlight and heat back into space. The controversial proposal is being taken seriously by scientists because Professor Crutzen has a proven track record in atmospheric research.
A fleet of high-altitude balloons could be used to scatter the sulphur high overhead, or it could even be fired into the atmosphere using heavy artillery shells, said Professor Crutzen, a researcher at the Max Planck Institute for Chemistry in Germany.
The effect of scattering sulphate particles in the atmosphere would be to increase the reflectance, or "albedo", of the Earth, which should cause an overall cooling effect.
Such "geo-engineering" of the climate has been suggested before, but Professor Crutzen goes much further by drawing up a detailed model of how it can be done, the timescales involved, and the costs.
In his forthcoming scientific paper, Professor Crutzen emphasises that the best way of averting global climate disaster is for countries to cut back significantly on their emissions of greenhouse gases, notably carbon dioxide produced by burning oil, gas and coal. But in the absence of such measures, and with the average global temperature expected to rise more than 3C this century, there may soon come a time when more extreme measures have to be considered, he said.
"If sizeable reductions in greenhouse gas emissions will not happen and temperatures rise rapidly, then climatic engineering, as presented here, is the only option available to rapidly reduce temperature rises and counteract other climatic effects," Professor Crutzen said.
"Such a modification could also be stopped on short notice, if undesirable and unforeseen side-effects become apparent, which would allow the atmosphere to return to its prior state within a few years," he said.
Such an idea is so controversial that some scientists opposed its publication in the peer-reviewed scientific press, fearing that it may encourage the view that it is easier to treat the symptoms rather than the causes of climate change.
Professor Crutzen, however, argues that the "grossly disappointing" international political response to the necessity of cuts in greenhouse gas emissions means that it should no longer be considered taboo to think about geo-engineering of the climate.
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