The storm that sank the “Bayesian,” a luxury yacht anchored off the Sicily coast, was sudden, violent and deadly — and scientists say it may be a warning of what’s to come as global warming fuels more extreme weather in the Mediterranean.
The superyacht, which was carrying 22 people, sank in the early hours of Monday morning, near the port of Porticello, claiming at least five lives. Rescue operations are still ongoing, hampered by the difficulties of reaching the vessel, which is resting on the sea floor approximately 165 feet deep.
The incident has shocked many. The Mediterranean, prized for its crystal clear, tranquil waters, is a prime summer destination for the very wealthy and their superyachts.
But these waters can still be dangerous — one of the reasons thousands of people die every year trying to migrate across it — and experts say it’s only becoming more so as human-caused climate change warms the sea, whipping up stronger and more intense storms.
The reasons for the sinking of the Bayesian are still being investigated. “It was dark and no images are available,” said Luca Mercalli, president of the Italian Meteorological Society.
But many believe the yacht was struck by a waterspout — one of several types of tornadoes. The coast guard reported the yacht was struck by a tornado, and a waterspout was reported to the European Severe Weather Database around the same time. Storms that day resulted in at least two dozen waterspout reports across Italy.
Waterspouts are narrow spinning columns of air below a thunderstorm which happen over water, and thrive on heat and humidity.
Most waterspouts are fairly weak “with a few seconds of strong, gusty winds before they move on or dissipate,” said Peter Inness, a meteorologist at the University of Reading. “But some can be much stronger.”
There aren’t huge amounts of data about waterspouts as they often happen unobserved out at sea, but there is evidence ocean temperatures can affect them. A study by University of Barcelona scientists, which was focused on Spain’s Balearic Islands, found waterspouts are more likely when the ocean is very warm.
However, drawing a link between climate change and more frequent or more intense waterspouts “is a step too far at the moment,” Inness said. They require several different conditions to form in addition to heat, including winds and temperature differences between the air and sea.
What is clear however, is that climate change is leading to more intense storms, some of which are fueled by warm ocean water.
And the Mediterranean is currently very, very hot.
Water temperatures around Sicily are approximately 30 degrees, Mercalli said. That’s 3 degrees Celsius (5.4 Fahrenheit) warmer than average for this time of year — an “extreme” anomaly, he told CNN.
While ocean heat is affected by natural climate fluctuations, such as El Niño, scientists are clear that it is being supercharged by human-caused global warming driven by burning fossil fuels.
When oceans are hot, they are able to inject more energy into the atmosphere. This can be converted into strong winds or rapid updrafts of air in thunderstorms, Inness said. Warm air is also able to hold more moisture, so when storms produce rain, it can be heavier and more intense.
There has been an increase in heavy thunderstorms dumping large amounts of rain, as well as downbursts — strong winds that descend from thunderstorms — in Italy and worldwide over the past few decades, Mercalli said.
The storm that hit Sicily reached the Mediterranean from the west, where it gained energy from high ocean temperatures, said Justino Martínez, a researcher at the Institute of Marine Scientists in Spain.
Spain’s Balearic Islands were particularly affected. Torrential rain last week flooded roads, forced evacuations and flight cancellations and overturned yachts moored on the popular island of Formentera.
The storm then gained more energy before reaching Italy, Martínez told CNN. In addition to the waterspout, other strong storms across Sicily brought torrential rainfall late Sunday, dumping more than 100 mm of rainfall, or 4 inches, in Brolo in less than four hours.
The Mediterranean region is on the frontlines of the climate crisis. Dubbed a climate change hot spot, it’s warming around 20% faster than the global average. And the toll is clear in the extreme weather the region is experiencing, from brutal rolling heat waves to ferocious storms bringing catastrophic flooding.
“Global warming — and specifically warming of the Mediterranean Sea — is quite likely to lead to an intensification of a number of potentially dangerous weather systems in that region,” Inness said.
Italy, surrounded by the fast-warming waters of the Mediterranean, is particularly affected. Last year, a downburst hit a ship on Lake Maggiore in northern Italy, killing four people.
The country also grappled with “once in a century” deadly floods that killed at least 14 people in May last year, while Sicily hit 48.8 degrees Celsius (119.8 Fahrenheit) last August, breaking Europe’s temperature record.
Outside Italy, last year’s Storm Daniel, fueled by unusually warm ocean waters, claimed lives in Greece, Turkey and Bulgaria. But by far the most devastation from the storm happened in Libya.
Flash flooding killed thousands of people following a so-called medicane — a rare, hurricane-like cyclone in the Mediterranean that gains energy from warm water.
“Global warming is intensifying all extreme weather events,” Mercalli said, “with huge costs for people and society.”