The flash floods that killed thousands of people in Libya this week followed a “drug” – a rare but destructive weather phenomenon that scientists say will intensify in a warming world.
The term is a fusion of the words “Mediterranean” and “hurricane”. Used by scientists and meteorologists, it is less known to the general public.
Medicanes, which tend to form over parts of the Mediterranean Sea near the coast of North Africa, are similar to hurricanes and typhoons, although they can develop over colder waters.
In satellite images, they look like a swirling mass of storm clouds with an eye in the middle.
Strong winds and around 170 millimeters of rain were unleashed by Storm Daniel when it made landfall in Libya on Sunday.
Scientists say the storm bore all the hallmarks of a drug.
“We are convinced that climate change is increasing the rainfall associated with such storms,” says Professor Liz Stephens of the University of Reading.
I don’t think it’s possible to imagine the destructive power of a dam burst, this video is truly terrifying.
In this situation, water management infrastructure added to the risk of #StormDanielthe exceptional precipitation of… https://t.co/oUOCerQYN2
– Professor Liz Stephens (@liz_stephens) September 12, 2023
Mediterranean cyclones are generally smaller and weaker than their tropical counterparts and have more restricted development space.
However, their maximum strength is generally the equivalent of a Category 1 hurricane on the Saffir-Simpson scale, encompassing speeds of 119 to 153 kilometers per hour.
Medicanes tend to form in the fall when the sea is warm, usually in the western Mediterranean and the region between the Ionian Sea and the North African coast.
A layer of colder air from higher altitudes forms convections with warmer air rising from the sea that converge around a center of low pressure.
Rare but deadly
The U.S. National Oceanic and Atmospheric Administration says the drugs form on average once or twice a year.
As hurricanes move from east to west, drugs tend to move from west to east.
Before hitting Libya, Storm Daniel also hit Bulgaria, Greece and Turkey last week.
Between 2016 and 2018, three medical accidents occurred off the coast of Greece, while in 2019 the Spanish meteorological services identified one between the Balearic Islands and the Algerian coast.
A drug blowing winds of up to 120 kilometers per hour, dubbed Ianos, hit Greece in September 2020, killing three people in the town of Karditsa and triggering floods, landslides and power outages.
The Italian island of Sicily was also hit in 2021.
In 2020, French weather service Météo France said it was difficult to assess climate signals emitted by drugs due to their scarcity.
While scientists are increasingly able to determine the likely effect of climate change on the likelihood and intensity of an extreme weather event, no such attribution studies have yet been performed on the storm Daniel.
Overall, experts say that warming sea surface temperatures, caused by human-induced climate change, will make extreme storms more intense.
The oceans have absorbed 90 percent of the excess heat produced by human activity since the start of the industrial age, scientists say.
Spanish researchers said the Mediterranean reached its highest temperature on record in July as Europe was gripped by a series of heatwaves.
Surface waters in the Eastern Mediterranean and Atlantic are two to three degrees Celsius warmer than usual, which would have turbocharged Daniel.
“The fact that Daniel can transform into medicine is probably due to warmer sea surface temperatures and thus human-induced climate change,” said climatologist Karsten Haustein from the University of Leipzig.