Spain, Portugal dryness ‘unprecedented’ in 1,200 years

PARIS: Parts of Portugal and Spain are the driest they have been in a thousand years due to an atmospheric high-pressure system driven by climate change, according to research published on Monday, warning of severe implications for wine and olive production.

The Azores High, an area of high pressure that rotates clockwise over parts of the North Atlantic, has a major effect on weather and long-term climate trends in western Europe. But in a new modelling study published in the journal Nature Geoscience, researchers in the United States found this high-pressure system "has changed dramatically in the past century and that these changes in North Atlantic climate are unprecedented within the past millennium".

Using climate model simulations over the last 1,200 years, the study found that this high-pressure system started to grow to cover a greater area around 200 years ago, as human greenhouse gas pollution began to increase. It expanded even more dramatically in the 20th century in step with global warming.

The authors then looked at evidence of rainfall levels preserved over hundreds of years in Portuguese stalagmites, and found that as the Azores High has expanded, the winters in the western Mediterranean have become drier.

The study cites projections that the level of precipitation could fall a further 10 to 20 percent by the end of this century, which the authors say would make Iberian agriculture "some of the most vulnerable in Europe".