Vast dust clouds from the Sahara desert are sweeping across the Atlantic and heading for the Caribbean and Florida this week.
While the clouds will likely create dramatic skies, public officials are warning those with allergies and respiratory problems that the spike in small-particle air pollution could exacerbate health conditions, and that some symptoms may mimic those of Covid-19.
The dust plumes, being swept by trade winds across the ocean from Mali and Mauritania, overlap with summer hurricane season and can cancel each other out, or at least reduce impacts.
The particles carried on the strong, dry winds can smother storm systems powered by Florida’s humid, tropical conditions.
Scientists and health experts have long monitored the plumes for their impacts.
Are the Sahara dust storms a new phenomenon?
No. Sand and dust storms occur annually when powerful, hot winds, sweep across loose soils on arid land. They can cause death and destruction in desert regions. For nearly 20 years, the World Meteorological Organization has sent sand and dust storm advisories but it remains tricky to get warnings to people in remote regions.
Although harmful to human health, the dust clouds deliver nutrient-laden minerals from the Sahara, the planet’s largest and hottest desert, to ocean life and vegetation in the Americas and the Caribbean.
In summer 2020, the dust storm was so huge it was dubbed “Godzilla” after winds swept nearly 24 tons from the Sahara to North and South America. It was so vast that astronauts tweeted photos of the dust cloud from the International Space Station.
Are they being impacted by the climate crisis?
Yes. After “Godzilla” took off last summer, NASA used satellite data and computer modelling to study the plumes.
Even though the size of dust clouds vary year to year and decade to decade, NASA scientists predict that the plumes will reach their smallest size in 20,000 years over the coming century due to the climate crisis and ocean heating.
Sea surface temperatures have a direct impact on wind speeds. If warming occurs in the northern Atlantic Ocean, then trade winds are weaker and can carry less desert dust.
Those weaker winds almost means bands of tropical rain more easily move into desert regions, keeping the sand damp and less likely to be blown away.
Smaller dust clouds are part of a feedback loop that is increasing global heating. Particles in the air have the ability to reflect the sun so with fewer suspended, more sunlight and heat reach ocean water, causing it to get even warmer.