Drought 'will spread across a third of planet'

Posted: 20 December 2006

Drought, threatening the lives of millions, will spread across half the land surface of the Earth in the coming century because of global warming, according to predictions from Britain's leading climate scientists. This report is by Michael McCarthy, Environment Editor of the Independent newspaper.

Extreme drought, in which agriculture is in effect impossible, will affect about a third of the planet, according to the study from the Met Office's Hadley Centre for Climate Prediction and Research.

It is one of the most dire forecasts so far of the potential effects of rising temperatures around the world - yet it may be an underestimation, the scientists involved said yesterday.

The findings, released at the Climate Clinic at the Conservative Party conference in Bournemouth [in October 2006], drew astonished and dismayed reactions from aid agencies and development specialists, who fear that the poor of developing countries will be worst hit.

"This is genuinely terrifying," said Andrew Pendleton of Christian Aid. "It is a death sentence for many millions of people. It will mean migration off the land at levels we have not seen before, and at levels poor countries cannot cope with."

Supercomputer model

One of Britain's leading experts on the effects of climate change on the developing countries, Andrew Simms from the New Economics Foundation, said: "There's almost no aspect of life in the developing countries that these predictions don't undermine - the ability to grow food, the ability to have a safe sanitation system, the availability of water. For hundreds of millions of people for whom getting through the day is already a struggle, this is going to push them over the precipice."

The findings represent the first time that the threat of increased drought from climate change has been quantified with a supercomputer climate model such as the one operated by the Hadley Centre.

Their impact is likely to even greater because the findings may be an underestimate. The study did not include potential effects on drought from global-warming-induced changes to the Earth's carbon cycle.

In one unpublished Met Office study, when the carbon cycle effects are included, future drought is even worse.

The results are regarded as most valid at the global level, but the clear implication is that the parts of the world already stricken by drought, such as Africa, will be the places where the projected increase will have the most severe effects.

Severity index

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 per cent, and the figure for extreme drought, currently 3 per cent, rising to 30 per cent.

Senior Met Office scientists are sensitive about the study, funded by the Department for Environment, Food and Rural Affairs, stressing it contains uncertainties: there is only one climate model involved, one future scenario for emissions of greenhouse gases (a moderate-to-high one) and one drought index. Nevertheless, the result is "significant", according to Vicky Pope, the head of the Hadley Centre's climate programme. Further work would now be taking place to try to assess the potential risk of different levels of drought in different places, she said.

The full study - Modelling the Recent Evolution of Global Drought and Projections for the 21st Century with the Hadley Centre Climate Model - [was published in October] in The Journal of Hydrometeorology.

Great concern

While the study will be seen as a cause for great concern, it is the figure for the increase in extreme drought that some observers find most frightening.

"We're talking about 30 per cent of the world's land surface becoming essentially uninhabitable in terms of agricultural production in the space of a few decades," Mark Lynas, the author of High Tide, the first major account of the visible effects of global warming around the world, said. "These are parts of the world where hundreds of millions of people will no longer be able to feed themselves."

Mr Pendleton said: "This means you're talking about any form of development going straight out of the window. The vast majority of poor people in the developing world are small-scale farmers who... rely on rain."

© 2006 Independent News and Media Limited

This article was published in The Independent on October 4,2006. Supplementary material may also be seen on The Independent website

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