Dust blown from the arid expanses of the Sahara desert is regularly carried into the sky above parts of Europe, with harmful impacts on air quality. But recently there has been an eightfold increase in these dust intrusions 鈥� even during colder months when they are unusual 鈥� and the spike in frequency and intensity has researchers concerned they are becoming more common.
鈥淚n 2024, we are having these extreme events again,鈥� says at the World Meteorological Organization, pointing to several dust intrusions over the Canary Islands and the western Mediterranean in the past three months. Another this week in Spain, carried on a hot wind known as a 鈥渃alima鈥�.
The Sahara desert is the source of more than half of all dust in the atmosphere, and during the warmer months of the year it is not uncommon for thick plumes of it to reach western Europe, with a few each year reaching as far north as the UK.
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However, over the past four years there have also been a series of intense dust intrusions in the northern hemisphere winter, from January to March, which is far more unusual, says Basart.
In February 2020, two exceptional dust events swept over the Canary Islands, resulting in hundreds of cancelled flights and blocking solar panels. Dust intrusions of record intensity also hit western Europe in early 2021 and 2022. 鈥淚t was unbelievable in Spain,鈥� says Basart.聽There were fewer of these abnormal dust clouds in 2023. But the dust is back this year.
To understand what might be driving these winter intrusions, Basart and her colleagues compared the unusual events between 2020 and 2022 with a satellite record of atmospheric dust extending back to 2003. She says the recipe for dust intrusions is straightforward: 鈥淭he ingredients are soils that can be uplifted and enough wind.鈥�
The researchers link the intrusions to an ongoing drought in the Maghreb region of north-west Africa, which is increasing the amount of dust available to be picked up by the wind. They also identify an area of anomalous heat in the western Mediterranean, as well as a jet stream 鈥渂locking鈥� pattern that results in more winds blowing north from the Sahara towards Europe.
鈥淭here was a change in the typical circulation patterns for wintertime,鈥� says Basart 鈥� although it is not yet clear whether this is a short-term anomaly or a more permanent trend.
at the Centre for Energy, Environmental and Technological Research in Spain says the change could be part of a longer-term increase in Saharan dust transport since the 1940s. Data on the dust intrusions doesn鈥檛 extend that far back, but he and his that atmospheric factors that make the intrusions more likely have increased since then.
He says desertification in the Sahara due to land use and climate change has also contributed to the volume of dust, with measurable . However, it is still unclear how climate change may be altering the circulation patterns behind dust intrusions, says at the University of Reading in the UK. 鈥淐limate models don鈥檛 even really agree on dust in the present climate, let alone what will happen to dust in the future,鈥� she says.
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