Drought Patterns in Parts of the World Haven't Been Seen in 1,200 Years

Drought Patterns in Parts of the World Haven't Been Seen in 1,200 Years ...

According to a monograph published Monday, parts of Portugal and Spain are the drytest they have been in a thousand years due to an atmospheric high-pressure system driven by climate change.

The Azores High, a zone of high pressure that oscillates clockwise over sections of the North Atlantic, has a significant impact on weather and long-term climate trends in western Europe.

Researchers in the United States found that this high-pressure system "has fundamentally changed in the past century," and that these changes in the North Atlantic climate are unprecedented within the last millennium.

This high-pressure system began to extend to a greater area around 200 years ago, as human greenhouse gas pollution began to rise, according to a climate model simulation.

In line with global warming, it grew significantly more significantly in the 20th century.

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

The study draws on projections that precipitation may drop another 10 to 20 percent by the end of this century, which would make Iberian agriculture "one of Europe's most vulnerable".

As greenhouse gas levels rise, the Azores High will continue to expand throughout the 21st century, putting the Iberian Peninsula at risk of drought and putting important crops at danger.

"Our findings have significant implications for future changes in the western Mediterranean hydroclimate," according to the authors.

Withering vines

According to the research, the Azores High acts as a "gatekeeper" for rainfall into Europe, with dry air descending in the summer months to cause hot, arid conditions in much of Portugal, Spain, and the western Mediterranean.

The high-pressure system surges during the cool, wetter winter months, sending westerly winds carrying rain inland.

This winter rain is "vital" for the region's ecological and economic well-being, but it has remained constant, especially during the second half of the twentieth century.

The authors claim that previous research did not uncover the effects of natural variability on the Azores High, but that its expansion during the industrial period is linked to an increase in atmospheric greenhouse gas concentrations.

Due to severe water constraints, a recent paper forecasts that the area suitable for grape growing in the Iberian Peninsula may shrink by at least a quarter and possibly disappear completely by 2050.

Researchers anticipate a 30-percent decrease in olive production in southern Spain by 2100.

Winemakers are already looking for strategies to adapt to the changing climate, such as moving vineyards to higher elevations or trying out more heat-tolerant varieties.

Climate change made a severe spring frost that ravaged grape vines in France more probable last year, making the plants grow earlier and therefore more susceptible to damage.

Agence France-Presse

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