Parts of Portugal and Spain are the driest in a thousand years due to a high-pressure atmospheric system driven by climate change, according to a study published Monday, which warns of a severe impact on wine and olive production.
The Azores High, an anticyclone rotating clockwise over parts of the North Atlantic, has a major impact on the weather and long-term climate trends in western Europe.
But in a new modeling study published in the journal Nature Geoscience, researchers in the United States found that this high-pressure system “has changed dramatically over the past century and that these changes in North Atlantic climate have been unprecedented over the past millennium.”
Using climate model simulations spanning the past 1,200 years, the study found that this high-pressure system began to grow to cover a larger area about 200 years ago, when human greenhouse gas pollution began to increase.
In the 20th century, it expanded even more dramatically, in step with global warming.
The authors then examined evidence of hundreds of years of preserved rainfall in Portuguese stalagmites and found that as the Azores High expanded, winters in the western Mediterranean became drier.
The study cites projections that rainfall could fall by a further 10 to 20 percent by the end of this century, which the authors believe would make Iberian agriculture one of the most vulnerable in Europe.
They warn that the Azores High will continue to expand in the 21st century as greenhouse gas levels rise, leading to an increased risk of drought in the Iberian Peninsula and threatening important crops.
“Our results have important implications for projected changes in the western Mediterranean hydroclimate over the course of the 21st century,” the authors said.
– vines wither –
The Azores High acts as a “gatekeeper” for precipitation into Europe, according to the study, with dry air plummeting in the summer months and causing hot, dry conditions across much of Portugal, Spain and the western Mediterranean.
During the cool, wetter winter period, the high pressure system swells, sending westerly winds that carry rain inland.
These winter rains are “vital” to both the ecological and economic health of the region, but have diminished, particularly in the second half of the 20th century.
While previous research had not unraveled the effects of natural variability on the Azores High, the authors said their results show that its expansion during the Industrial Era is linked to increases in atmospheric greenhouse gas concentrations.
A study cited in the latest research estimates that the area suitable for viticulture in the Iberian Peninsula could shrink by at least a quarter by 2050 and possibly disappear almost entirely due to severe water shortages.
Meanwhile, researchers have predicted a 30 percent drop in production for the olive regions of southern Spain by 2100.
Winemakers are already looking for ways to adapt to the changing climate, such as B. moving vineyards to higher elevations and experimenting with more heat-tolerant cultivars.
Last year, scientists found that a severe spring frost that devastated grapevines in France was made more likely by climate change as the plants sprouted earlier and were therefore more vulnerable to damage.
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