Global warming: a moral imperative

In his movie "An Inconvenient Truth", former US Vice President Al Gore says that preventing global warming is a moral imperative. Today's Independent tells us why. According to a new study from the Hadley Centre for Climate Prediction and Research, global warming will lead to extreme drought affecting a third of the planet:

The study, by Eleanor Burke and two Hadley Centre colleagues, models how a measure of drought known as the Palmer Drought Severity Index (PDSI) is likely to increase globally during the coming century with predicted changes in rainfall and heat around the world because of climate change. It shows the PDSI figure for moderate drought, currently at 25 per cent of the Earth's surface, rising to 50 per cent by 2100, the figure for severe drought, currently at about 8 per cent, rising to 40 cent, and the figure for extreme drought, currently 3 per cent, rising to 30 per cent.

(Clearly, these figures are not exclusive; less severe categories include the more severe ones).

The study is limited, in that it only uses one climate model and one emissions scenario (moderate to high - which we sadly seem to be on track for), and yet at the same time it is likely to be too optimistic, as it doesn't include important feedback effects on the carbon cycle (which would tend to push things towards even greater emissions and therefore greater warming). But the findings are frightening enough. What we are looking at is vast stretches of the world becoming effectively unsuitable for agriculture. In wealthy countries, where we have efficient food and water distribution systems, this will merely make life slightly uncomfortable. But in the third world, where people are more dependent on local agriculture and water supplies, it will mean famine and death on a massive scale - a slow motion disaster which will kill hundreds of millions over the next century. Stopping that is definitely a moral imperative.