MADRID – Once again, people in large parts of Spain – from Andalucia to Burgos – are being warned about large amounts of Sahara desert dust in the air. The meteorological phenomenon known in Spain as ‘calima’ is more common than usual.
The frequency and intensity with which dust from the Sahara has reached the Iberian Peninsula this year is unprecedented and leaves researchers wondering what the future holds. In a large part of Spain, the air quality has been very bad in recent days. In Madrid, the advice is that people should not practice sports outside for a long time and that those with respiratory diseases should wear a mask. The same goes for people with fragile health.
A sepia filter over the world
You can see that there is Sahara dust in the air. It’s like seeing the world through a sepia filter. The greater the density of the dust, the more orange-brown the sky turns. Moreover, a lot of dust in the air is bad to breathe. Therefore, when the phenomenon lasts for days, it can become problematic.
Calima is relatively common in the Canary Islands. After all, they lie off the coast of West Africa at the height of the Sahara and when there is an easterly wind there is almost always desert nitrogen in the air. While the phenomenon on the Spanish mainland and to the north of Europe was still rare at first, the population is almost getting used to it. This year, 2022, records will be set.
The most unusual episode happened in March when a blanket of dust covered our streets, the sky took on an apocalyptic orange hue and the dust reached half of Europe. Moreover, with bad weather, it rained pure mud. That mud rain turned whole villages brown. Façade cleaners could not cope with the amount of work for weeks.
It never got that bad after March, but the desert dust came back repeatedly. Even in the north of Spain, for example in May, when the calima was accompanied by high temperatures. And last week, when Sahara dust caused very poor air quality indices in several autonomous regions.
One-off or trend?
Meteorologists and other scientists are now wondering whether we are dealing with a one-off extremity or a trend. They are at least surprised by what is happening. For example, meteorologist Emilio Cuevas, belonging to the State Meteorological Agency (Aemet), is working on a scientific study on the intrusion of Saharan dust in Spain over the past 20 years. The research is based on satellite data, the Copernicus system, the World Meteorological Organization and the Supercomputing Center of Barcelona.
“We are verifying an increase in these episodes and we want to know what meteorological phenomena could explain this,” he said in statements to El Confidencial. While his analysis spans the last two decades, the most notable happened between 2020 and 2022. “We’ve had three very notable winters, particularly the months of February and March. People were even skiing on reddish snow in the Sierra Nevada, the Pyrenees and the Alps.” Airports such as Almería also suffered from the calima, which greatly deteriorates visibility, making it difficult for planes to land.
Normally such a calima lasts for a short time and has a low intensity and occurs around the summer. This year, the episode between March 15 and 31 was particularly extreme in Western Europe. But what has happened in the past few days, mid-October is also unprecedented. This week’s calima is associated with a DANA (high-level isolated depression), but it’s “an abnormal DANA,” the expert says. Although these phenomena are frequent at this time and in the Mediterranean region and cause violent storms in the Levante area, the peculiarity of them is that “the dust has been massively transported to both the peninsula and the Canary Islands”.
The fact that this nebula moved to the Atlantic and north at the same time is “new,” Cuevas emphasizes. For example, the historic calima of February 2020, forced all airports in the Canary Archipelago to close. This calima eventually moved more weakened to the European continent in two directions.
Previously, the Saharan dust barely reached the Iberian Peninsula in winter and spring, mainly affecting other countries in the Eastern Mediterranean.
Does all this have to do with climate change? Cuevas’ answer is as sincere as it is inconclusive: “We don’t know. Whether this is here to stay, the observations of the coming years will tell us.” Things are indeed changing and “we suspect there is a connection but it is just speculation” as scientific data is lacking.
Unlike temperatures and precipitation, which allow very accurate models to be made, in the case of Sahara dust, it is very difficult to talk about trends. One of the reasons is the complexity of the phenomenon. Another is that the records are very short. Moreover, the fact that the calima has become significantly more frequent over the past three years does not necessarily mean that this trend will continue over time.
400% increase in 5,000 years
A study published in 2021 in the journal Science Advances by researchers at the Complutense University of Madrid (UCM) shows that the arrival of dust from the Sahara in the Iberian Peninsula has increased by 400% over the past 5,000 years. That research shows that dust ingress from the Sahara can be highly variable over time and linked to climate change, but it doesn’t say much about what’s happening today.
Sahara continues to grow
In addition, the Sahara desert continues to grow. At the beginning of the 21st century, it was at least 10% larger than it was in 1920, according to a study published in the “Journal of Climate.” This also means that more particles can be transported by air currents.
The particle concentration records of the Ministry of Ecological Transition and the Demographic Challenge are a source of information about the impact of African dust. Monitoring this data is essential for health, as it involves analyzing air quality. Thus we know that although periods of calima differ, in the southeastern corner of the peninsula some Saharan dust is recorded up to 30% of the days of the year, the same as in the Canary Islands.
Research in the Sierra Nevada
This kind of data can also be counted in a more indirect way. At the University of Granada, a group of experts analyzed the lagoons of the Sierra Nevada over 10 years in search of the footprint left not only by the dust of the Sahara but by everything that comes with it. As stated in an article published in “Scientific Reports” in 2018, the increase in calima caused an increase in nutrients that led to the decline of a type of algae that is essential in the food web of these aquatic ecosystems.