Screening sunlight from the sky with sulphates is not, though, the only suggestion around.

ECONOMIST: Geoengineering

There, it will form sulphates that reflect a fraction of the incident sunlight, resulting in a net reduction in global temperatures.

ECONOMIST: The controversy over SuperFreakonomics

The researchers were also able to see a rise in temperatures after 1970 - the consequence of clean air legislation cutting emissions of soot and sulphates.

BBC: Particles from fossil fuels 'affect the growth of corals'

Ken Caldeira of Stanford University, another of the authors, reckons that it may be feasible to place sulphates in the stratosphere near the poles and thus cool the Earth in a place where global warming manifests itself most strongly, though that would scarcely please the Russians and the Canadians.

ECONOMIST: Global warming