Climate graphic of the week: Catastrophic Libyan flooding fuelled by warming oceans

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Scientists say catastrophic floods in Libya were caused by a “drug” – a powerful cyclone with hurricane-like characteristics that can reach as far as the Mediterranean, Ionian Sea and North African coasts.

Storm Daniel battered Libya this week, battering Greece, Bulgaria and parts of Turkey, killing thousands and causing a dam to collapse in the port city of Derna.

Experts say drug incidents are relatively rare, occurring one to three times a year, but can cause devastating flooding, storm surges and strong winds.

Storm Daniel hits Greece, Türkiye and Libya

Animation showing rain from Storm Daniel over Greece, Turkey and Libya

Temperatures in the eastern Atlantic and eastern Mediterranean are 2-3°C above normal, causing particularly heavy storms and rainfall.

The area also experienced a high-pressure blocking pattern that trapped the storm over Greece. When it finally moved, it evolved into a drug that brought huge amounts of rain to Libya.

Heavy rains of 150 mm to 240 mm caused flash floods in several cities, including Al-Bayda, which recorded Record 414.1 mm in 24 hours.

Map showing cumulative rainfall from Storm Daniel between September 4 and 12

The World Meteorological Organization said sea surface temperatures off the coast of Libya exceeded 27.5°C, increasing the risk of storms.

“Warmer water temperatures will not only increase the intensity of rainfall, but also make storms more ferocious,” said Carsten Haenstein, a climate scientist and meteorologist at the University of Leipzig. “The fact that Daniel can be made into medicine . . . is very It could be a result of rising ocean surface temperatures and man-made climate change.”

Most drugs have a radius of 70 to 200 kilometers and retain their tropical characteristics for up to three days. They can travel 1,000 to 3,000 kilometers until they lose contact with the sea surface that powers them. Although the phenomenon occurs year-round, activity usually peaks between September and January.

Experts say Libya’s infrastructure is clearly overwhelmed by heavy rainfall.

Even if a dam does have a spillway, water levels can be too high.

“If you experience heavy rainfall over a significant period of time, the reservoir fills up and the spillway activates because you want to avoid water overflowing the dam and eroding the structure, which can result in loss of stability,” Du said. Simon Mathias of the University of London said. “The spillway may not be able to carry the water fast enough.”

The World Meteorological Organization said many of the casualties could have been avoided if Libya had better weather services to provide information and warnings. At least 5,500 people were declared dead and 10,000 missing.

Some academics say that while rising temperatures increase the likelihood of extreme weather events, it’s too early to link such events to climate change.

Lizzie Kendon of the University of Bristol said: “We should expect extreme events unprecedented in the observational record.”

“Storm Daniel illustrates the type of devastating flood events we may increasingly expect in the future, but such events may occur simply due to natural changes in climate, as they have in the past.”