Injecting sulphate particles into the stratosphere, for instance, would cool the Earth by reflecting more sunlight into space. (Nature has already shown that this concept can work, since volcanic eruptions that send sulphur-rich plumes into the stratosphere can temporarily alter the world's climate.) However, Dr Lenton notes that the method becomes less effective as the atmosphere becomes more saturated with particles.

ECONOMIST: Geo-engineering

Overzealous and effective theft detection and prevention creates an atmosphere that is likely to intimidate innocent customers.

NEWYORKER: The Secret Shopper

The most effective way to deal with radon is to fit an air pump to a property to vent the gas into the atmosphere.

BBC: Radon