Spain and Portugal could be hit by “megadroughts” lasting for many years by the end of the century, according to climate models.

If the worst projections are correct, the area could see a 15-year period of rainfall at less than half the average level.

Researchers from Newcastle University selected a total of 15 different climate models used by leading scientific bodies around the world, including Nasa, the Met Office and the Max Planck Institute for Meteorology.

They found that, while the models produced a range of different results, “extreme future droughts” were predicted by ones which could accurately simulate what had happened in the past.

Portugal has been hit by eight major droughts since the 1940s, with the most intense taking place from 2004 to 2006.

Spain has seen three major droughts – the latest of which spanned 1990 to 1995 – affecting most of the country, with rainfall reduced by up to 30 per cent, but has also experienced a number of smaller ones more recently.

The researchers examined the three main river basins of the Iberian Peninsula, the Tagus, Douro and Guadiana.

Writing in the International Journal of Climatology, they said: “All models project an intensification of drought conditions for the Douro, Tagus and Guadiana.

“However they strongly disagree on the magnitude of these changes.

“Some project small increases in drought conditions but most project multi-year droughts reaching up to ... eight years of mean annual rainfall missing [over a 15-year period] ... by the end of the century.

“Despite the fact that the two models projecting the most severe future drought conditions overestimated historical drought, extreme future droughts were also projected by models that simulated historical droughts with similar conditions to the observations.”

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A previous study found parts of southern Europe could become a desert by 2100, as global warming changes the ecosystem “in a way that is without precedent” in the last 10,000 years.