Desertification threatens 30% of earth’s surface

Deserts could expand to cover almost a third of the world's surface by the end of the century under climate change, a study of future global drought conditions has found.

The Met Office study, the first of its kind, predicted an increase in the area affected by the most extreme drought from 3 to 30%, areas of severe drought up from 8 to 40% of total land area, and up to half of the earth’s surface affected by moderate drought at any one time.

Scientists from the Met Office used the IPCC’s medium high emission scenario to drive a climate model, simulating the complex processes of regional rainfall, evaporation and run-off. They classed the results using the Palmer Drought Severity Index (PDSI), a common method on which the US and other countries base their drought alerts, with extreme drought defined as the top 1% of the PDSI scale and severe drought as the top 10%.

Looking back on the increasing degree of desertification across the world over the last 50 years, scientists found strong evidence to suggest this was caused by man-made global warming. A control run of the model simulating the evolution of a climate free of human emissions showed almost no change to drought conditions.

Dr Eleanor Burke, who carried out the research together with colleagues from the Met Office’s Hadley Centre, said: “These results are very sobering but it must be pointed out that further research is required to substantiate what is the first look at this issue.

“However, it does indicate the potential seriousness of future climate change impacts if CO2 emissions continue to increase substantially.”

While the model predicted global drought conditions with good accuracy, it had some trouble reproducing regional differences. Further research should fill in some of the detail on which regions will be most affected, the Met Office said.

The results of the study, published in the Journal of Hydrometeorology on Thursday, came in the middle of heated political debate on a “climate change law” that would set binding targets for cutting the UK’s carbon emissions.

Chris Huhne MP, environment spokesman for the Liberal Democrats, said in response to the Met Office study: “This is yet more evidence of the chaos we will face if action is not taken on climate change.

“The Government must introduce measures including green taxes to bring about the changes in behaviour needed to halt climate chaos.

“Every day that the Government dithers brings us closer to the point of no return.”

Goska Romanowicz

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