WHY DOES IT HAPPEN AND WHEN, IS THERE A SEASON FOR IT? IS CLIMATE CHANGE MAKING THESE EPISODES MORE FREQUENT OR INTENSE? WHAT ARE THE MOST IMPORTANT KNOWN EPISODES? IS SAHARAN DUST HARMFUL FOR HEALTH? A FUNDAMENTAL PIECE IN THE ATMOSPHERE, CLIMATE AND WEATHER PUZZLES DUST TO DUST NOT ONLY SAHARAN: THE OTHER HOTSPOTS IN THE DUST BELT MODELS AND FORECASTS HOW CAMS AND BARCELONA DUST CENTER KEEP TRACK OF THESE EPISODES

Hazy skies, warm-coloured sunsets, dirty cars and poor air quality are some of the most visible signs of the dust transport episodes. In recent years Europe and the Caribbean have experienced some remarkable Saharan dust events sparking many questions about the influence of climate change in its frequency or intensity, and moreover about its effects on our health.

It is probably less known that long-range dust transport is a key variable of the atmosphere playing a role in weather, climate and atmospheric composition.

Given its gigantic extension, the Sahara Desert is the main global source of atmospheric dust, but there are other important hotspots around the so-called dust belt. The Gobi Desert is the main dust source in Asia with transport reaching as far as the Hawaiian Islands.

Here are some key aspects of dust transport.
Why does it happen and when, is there a season for it?
Dust transport depends on two main factors: the availability of light, dry mineral and organic sediment sources –of which the world’s deserts are an endless supply- and wind conditions favouring the injection of particulate matter into the troposphere and its transport.

Therefore, in general dust episodes tend to be seasonal, following the changes in wind conditions. Wind patterns will also determine the size of particulate matter loft or the height at which the dust cloud will travel.

Saharan Dust transport towards the Caribbean following trade winds is more likely to happen during spring, summer and early fall, when the Saharan Air Layer forms crossing the Atlantic with very dry, dusty air masses.

Early spring is the most active period for Saharan dust transport into Europe.

Is climate change making these episodes more frequent or intense?
Drought conditions and desertification associated with global warming can increase the amounts of dust available. Unsustainable water and land use also favour increased amounts of dust. research based on evidence hasn’t shown clear trends, despite some notorious recent episodes

Some studies predict shifts in atmospheric conditions will lead to less frequent but more intense Saharan Dust Episodes. A recent scientific paper found that dust transport episodes in western Mediterranean increased since 1948 both in frequency and intensity.

Other projections predict increased rainfall in the region due to higher evaporation. If this trend is confirmed, this new “Greening of the Saharan desert” would result in reduced amounts of dust available for transport in the regions concerned.

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