The most obvious effects of global warming can be seen in the changing weather patterns we are already beginning to experience. This has been highlighted by an  apparent increase in catastrophic weather events – the European heatwave of 2003, which killed 50,000 people; devastating floods in Mumbai in 2005 following 944mm of rainfall in twenty-four hours; the city of New Orleans wiped out by Hurricane Katrina.  These headline grabbing events have all been directly attributed to global warming, but should more accurately be viewed as indicative of disturbing changes in established weather patterns. 

 Researchers at the UK's Hadley Centre, have calculated that a heatwave like that of 2003 is now four times more likely to occur due to the rise in greenhouse gases. This increase in temperature in turn contributes to a growing pattern of drought and flooding around the world. Higher temperatures cause more water to evaporate from the oceans, this water vapour cools in the upper atmosphere leading to increasingly intense rainfall and subsequent devastating floods. As oceans warm they also give birth to hurricane's like Katrina. These storms, have been increasing in intensity and the 2005 season, which produced Katrina, was notable as the first on record to have four category 5  hurricanes. The same process of evaporation which has fuelled such intense storms, also sucks moisture from the ground in more arid regions and is responsible for a sustained drought across southern Africa. 

 At the poles, the ice caps have experienced the most dramatic changes of all.  As temperatures have risen, the Arctic has begun to melt at an alarming rate, while enormous ice shelves have split off from Antarctica.  This melting ice adds volume to  oceans already swollen by raised temperatures and may result in a rise in sea levels by as much as 480mm by the end of the century, inundating many low lying regions including the Maldive Islands and Bangladesh.  The sheer complexity of predicting weather patterns mean that many of these projections are best estimates based on current data, but as recent experience has shown, we face an uncertain future climate with a potentially devastating cost in terms of lives and property.