Parts of Portugal and Spain are the driest in a thousand years due to a high pressure system driven by climate change, according to a study published on Monday that warns of serious consequences 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 influence on weather and long-term climate trends in Western Europe.
But in a new modeling study published in the journal Natural scienceresearchers in the United States found that this high-pressure system “has changed dramatically over the past century and that these changes in the North Atlantic climate are unprecedented over the past millennium.”
Using climate model simulations of the past 1,200 years, the study found that this high-pressure system began to grow and cover a larger area about 200 years ago, when 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 precipitation levels preserved over hundreds of years in Portugal’s stalagmites and found that as the Azores expanded, winters in the western Mediterranean became drier.
The study cites predictions that rainfall could drop another 10 to 20 percent by the end of this century, which the authors say would make Iberia’s agriculture “one of the most vulnerable in Europe.”
They warn that the Azores High will continue to expand throughout the 21st century as greenhouse gas levels rise, increasing the risk of drought in the Iberian Peninsula and threatening key agricultural crops.
“Our findings have important implications for projected changes in the hydroclimate of the Western Mediterranean during the 21st century,” the authors said.
According to the study, the Azores may act as a “guard” for precipitation in Europe, with dry air sinking into summer months causing hot, dry conditions over much of Portugal, Spain and the western Mediterranean.
During the cool and wet winter, a high pressure system swells, sending westerly winds that carry rain inland.
This winter rain is “vital” to both the ecological and economic health of the region, but its amount is decreasing, especially in the second half of the 20 century.
While previous studies have not disentangled the effects of natural variability on the Azores, the authors said their findings show that their expansion during the industrial age is linked to increased atmospheric concentrations of greenhouse gases.
Research cited in the latest study suggests that the area suitable for growing grapes in the Iberian Peninsula could shrink by at least a quarter and potentially disappear almost entirely by 2050 due to severe water shortages.
Meanwhile, researchers predicted a 30 percent drop in olive production in southern Spain by 2100.
Winemakers are already looking for ways to adapt to the changing climate, such as moving vineyards to higher altitudes and experimenting with more heat-tolerant varieties.
Last year, scientists discovered that severe spring frosts had devastated vines in France was done in a more probable way climate changeat the same time, the plants bloom before the buds and are therefore more susceptible to damage.
Nathaniel Cresswell-Clay and others. The high expansion of the Azores in the twentieth century, unprecedented in the last 1200 years, Natural science (2022). DOI: 10.1038/s41561-022-00971-w
© 2022 AFP
Citation: Spain, Portugal ‘unprecedented’ dryness in 1,200 years (2022, July 4) Retrieved July 4, 2022, from https://phys.org/news/2022-07-spain-portugal-dryness-unprecedented-years. html
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