Nobel Prize-winning chemist Paul J. Crutzen has a radical plan to reverse global warming: shooting some 5 billion kg of sulfur into the atmosphere using artillery to simulate a small volcanic eruption.

The idea is based on the effect of the 1991 eruption of Mount Pinatubo in the Philippines, which threw about 6 billion kg of sulfur into the air, resulting in a 0.5 °C cooling at Earth's surface for a year thereafter.

Crutzen details his proposal in the upcoming August issue of Climatic Change, an academic journal.

Coincidentally, the Pentagon's non-lethal weapons program includes research into sulfur-based weapons, otherwise known as stink bombs.

In 1998, the Pentagon commissioned scientist Pam Dalton, from the Monell Chemical Senses Centre in Philadelphia, to test disgusting odours.

One question she was trying to answer was whether there were different cultural reactions to bad smells. She tested the odours on five ethnic groups.

She found that two smells transcended cultural barriers: one is called US Government Standard Bathroom Malodour, a horrendously concentrated stink of human faeces.

Dalton said: 'It's very pungent... more precisely, it smells like shit, but much, much stronger. It fills your head. It gets to you in ways that are unimaginable. It's not something you are likely to come across in the real world.'

She said that the smell made volunteers scream and curse after just a few seconds of exposure, even though it is quite harmless.

The other odour which produced the desired results was known as 'Who Me?' - a collection of sulphur molecules that stank of rotting carcases and spoilt food.

Time to start worrying about global gagging.