The flash flood that has killed hundreds of individuals in Libya this week adopted a “medicane”, a uncommon however harmful climate phenomenon that scientists imagine will intensify in a warming world.
The time period is an amalgamation of the phrases Mediterranean and hurricane. Utilized by scientists and climate forecasters, it’s much less well-known to the broader public.
Medicanes, which are likely to kind over components of the Mediterranean Sea close to the north African coast, are much like hurricanes and typhoons though they will develop over cooler waters.
They’ll additionally bear a bodily resemblance on satellite tv for pc imagery as a swirling mass of storm clouds surrounding a watch within the center.
Fierce winds and rain are unleashed; Storm Daniel dumped roughly 170 millimetres of rain in Libya. It will intensify with world warming, scientists say.
“We are confident that climate change is supercharging the rainfall associated with such storms,” mentioned College of Studying professor Liz Stephens.
The Mediterranean cyclones are normally smaller and weaker than their tropical equivalents and have a smaller area wherein to develop.
Their peak energy is normally the equal of a Class 1 hurricane on the Saffir-Simpson scale, encompassing speeds of 119-153km (74-95 miles) per hour.
Medicanes are likely to kind within the autumn when the ocean is heat, normally within the western Mediterranean and the area between the Ionian Sea and the north African coast, defined Suzanne Grey, a professor on the College of Studying’s meteorology division.
A layer of colder air from larger altitudes varieties convections with hotter air rising from the ocean that converge round a centre of low strain.
Medicanes kind a couple of times per yr on common, in keeping with the US Nationwide Oceanic and Atmospheric Administration.
Whereas hurricanes transfer from east to west, medicanes are likely to go from west to east.
Earlier than putting Libya, Daniel pummelled Bulgaria, Greece and Turkey final week.
Three medicanes occurred off Greece between 2016 and 2018, whereas in 2019 Spanish climate providers recognized one between the Balearic Islands and the Algerian coast.
A medicane packing winds of as much as 120 kilometres per hour, dubbed Ianos, lashed Greece in September 2020, killing three folks within the metropolis of Karditsa and triggering floods, landslides and energy cuts.
The Italian island of Sicily was additionally struck in 2021.
In 2020, French climate monitor Meteo-France mentioned it was troublesome to work out local weather indicators from medicanes as a result of their rarity.
Whereas scientists are more and more capable of unpick the possible impact of local weather change on the chance of an excessive climate occasion occurring and its depth, no such attribution research has but been carried out on Daniel.
Usually, consultants say the warming of sea floor temperatures, pushed by human-induced local weather change, goes to make excessive storms extra intense.
Oceans have absorbed 90% of the surplus warmth produced by human exercise for the reason that daybreak of the economic age, in keeping with scientists.
Spanish researchers mentioned the Mediterranean reached its highest temperature on report in July as Europe baked below a sequence of heatwaves.
The floor waters of the jap Mediterranean and Atlantic are two to 3 levels Celsius hotter than common, which might have turbocharged 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 local weather scientist Karsten Haustein of Leipzig College in Germany.
