The flash flood that killed thousands of people in Libya this week was caused by a “medicane,” a rare but catastrophic weather phenomena that experts fear will become more common as the planet warms.
The name combines the words Mediterranean and hurricane. It is less well recognized to the general public but is used by scientists and weather forecasters.
Medicanes are comparable to hurricanes and typhoons in that they form over sections of the Mediterranean Sea along the north African coast, however they can form over milder seas.
They can also appear on satellite images as a swirling mass of storm clouds surrounding an eye in the center.
Storm Daniel unleashed strong winds and rain in Libya, dumping roughly 170 mm of rain. According to scientists, global warming will exacerbate this.
We are confident that climate change is supercharging the rainfall associated with such storms.”
University of Reading professor Liz Stephens
Mediterranean cyclones are often smaller and weaker than their tropical counterparts, with less area to develop.
Their maximum power is usually the equivalent of a Category 1 hurricane on the Saffir-Simpson scale, with winds ranging from 119 to 153 kilometers per hour (74 to 95 miles per hour).
Medicanes emerge in the autumn when the sea is warm, mainly in the western Mediterranean and the region between the Ionian Sea and the north African coast, according to Suzanne Gray, a meteorology lecturer at the University of Reading.
A layer of cooler air from higher elevations generates convections with warmer air rising from the sea, which converge around a low-pressure center.
According to the US National Oceanic and Atmospheric Administration, Medicanes form once or twice every year on average.
Last week, Daniel bombed Bulgaria, Greece, and Turkey before invading Libya.
Between 2016 and 2018, three medicanes occurred off the coast of Greece, while in 2019, Spanish weather services discovered one between the Balearic Islands and the Algerian coast.
Ianos, a medicane packing winds of up as 120 km/h, slammed Greece in September 2020, killing three people in the city of Karditsa and causing floods, landslides, and power outages.
In 2021, the Italian island of Sicily was also affected.
Due to the rarity of medicanes, French weather monitor Meteo-France stated in 2020 that it was impossible to extract climate signals from them.
While scientists are becoming capable of determining the likely impact of climate change on the likelihood and intensity of catastrophic weather events, no such attribution study has yet been conducted on Daniel.
In general, experts believe that rising sea surface temperatures caused by human-caused climate change would intensify violent storms.
According to scientists, the oceans have absorbed 90% of the surplus heat produced by human activities since the dawn of the industrial age.
The Mediterranean hit its hottest temperature on record in July, according to Spanish researchers, as Europe burned under a succession of heatwaves.
The eastern Mediterranean and Atlantic surface waters are two to three degrees Celsius warmer than usual, which would have accelerated Daniel.
The fact that Daniel could form into a medicane … is likely a result of warmer sea surface temperatures and hence human-made climate change,” added climate scientist Karsten Haustein of Leipzig University in Germany.