For a country suffering its longest drought on record, rainfall of 2.7 inches in the capital city might be a cause for satisfaction. Unfortunately, it fell in a single hour in Canberra at the end of February. Freak storms left three-foot drifts of hail, damaging hundreds of buildings, led to flash flooding in Sydney, and showed a paradox of climate change: an increase in both droughts and floods. The storms, like other “extreme weather events” such as Hurricane Katrina, cannot be attributed directly to global warming. But meteorologists say they illustrate dramatically some of its expected effects.

Storms will become more frequent, according to prediction models. But large areas of the world will be affected by severe droughts. Given these twin effects, many regions could suffer a “double whammy” – water shortages coupled with heavy rainfall that could cause mudslides, sweep away crops and topsoil and damage buildings. Research into the Indian monsoon revealed how changes to rainfall patterns may already be taking place in one of the world’s biggest agricultural economies.