August 17, 2022

Spain and Portugal are the driest they’ve been in over a thousand years, due to climate change

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Research published this Monday warns that Spain and Portugal are bearing the full brunt of climate change, with parts of these countries being the dryest they’ve ever been in a thousand years.

Image via Pixabay

The Iberian Peninsula, home of Spain and Portugal, is famous for its hot sun, inviting beaches, and absolutely delicious food and wine. But the people living there, alongside aficionados of local products made from grapes and olives have cause for great concern: according to a new paper, parts of this peninsula are dryer than they have been in over a thousand years, with “severe implications” for wine and olive production.

Man-made climate change sits at the root of this development.

Of things to come

The weather patterns of Western Europe, as well as its long-term climate trends, are influenced to a great extent by the Azores High — also known as the North Atlantic (Subtropical) High. This is an area of high pressure that moves and rotates over parts of the North Atlantic. The traditional droughts seen in the Mediterranean Basin during summertime are, to a very large extent, due to the seasonal activity of this system.

But, according to a new study led by researchers at the Woods Hole Oceanographic Institution, the behavior of the Azores High has been in flux over the last century. During this time, they report, it has “changed dramatically”, leading to climatic changes in the North Atlantic area that “are unprecedented within the past millennium”.

For the study, the team ran computer simulations of the climate in this area over the last 1,200 years. The simulations were supplemented with data on historic rainfall levels, obtained from the study of stalagmites from cave systems in Portugal.

These simulations revealed that the high-pressure system started to increase in size around 200 years ago, closely aligned with the onset of the Industrial Revolution and the build-up of man-made greenhouse gases in the atmosphere. As industrial activity ramped up, the growth rate of the Azores High increased as well. The stalagmites revealed that, as the Azores High expanded, winters in the western Mediterranean have also become drier.

During summer, this weather system brings dry air from Africa over Western Europe, causing hot and arid conditions over the western Mediterranean, most notably in Spain and Portugal. In the winter, it brings wet air from the west, which brings rain. These winter rains have become essential for the health of ecosystems and human communities in the area. However, the amount of winter rain has been steadily decreasing, particularly over the second half of the last century.

Running these simulations into the future, the team found that the Azores High will keep expanding throughout the 21st century due to rising greenhouse gas levels in the atmosphere. The Iberian Peninsula is especially at risk; levels of precipitation in the area could drop by a further 10% to 20% by the end of the century — which means that agriculture in the Iberian Peninsula is “some of the most vulnerable in Europe”.

They cite a previous study that found that the areas suitable for growing grapes in the Iberian Peninsula could shrink by at least 25%, and potentially vanish completely, by 2050, mainly due to low precipitation. Regions suitable for the growing of olives in southern Spain are predicted to shrink in size by 30% by 2100.

“Our findings have important implications for projected changes in western Mediterranean hydroclimate throughout the twenty-first century,” the authors said.

Although there is some natural variability in the intensity of the Azores High’s effects, the authors say that their work shows that the accumulation of man-made greenhouse gases in the atmosphere is what is driving its current expansion.

The paper “Twentieth-century Azores High expansion unprecedented in the past 1,200 years” has been published in the journal Nature Geoscience.