They are called ‘Medicanes’, Mediterranean hurricanes. How devastating and deadly they can be appeared in Libya on September 10. Storm Daniel reached a peak over the northeast of the country, with average wind speeds of seventy to eighty kilometers per hour, but above all with large amounts of precipitation, locally between 150 to 240 millimeters in one day. More than 414 millimeters fell above the city of Al-Bayda between September 10 and 11 in the morning, the World Meteorological Organization writes based on the scant data from Libya itself. That is the largest amount of rain ever measured in dry land.
Storm Daniel had already been in the region for about six days. It developed from a low-pressure area above Greece, where a measuring station in the village of Zagora recorded as much as 750 millimeters of rain on September 5 – the same amount as usually falls there in a year and a half.
Omega blockade
It was the downside of the sweltering autumn weather in the Netherlands and Germany, says Dim Coumou, professor of weather extremes at the VU in Amsterdam. Coumou explains that a so-called omega blockage had arisen, a loop in the jet stream, which caused exceptionally warm September days in the Netherlands and a severe depression with cold air from the north in Greece.
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According to Coumou, these types of blockages can be quite “persistent”. “Usually in Europe we deal with a westerly current,” he explains. “It ensures that the weather changes a little every two to five days. But due to such a blockage, the weather can remain the same for a long time. A week to ten days and sometimes even several weeks. Omega blockages also existed a century ago, but in a warmer atmosphere this can cause higher temperatures or more extreme showers. Then you get the most intense heat waves, such as in 2003 in Western Europe and in 2010 in Russia.”
Storm Daniel also raged over the western part of Turkey and Bulgaria, before gaining significant strength above the sweltering seawater of the Mediterranean Sea and becoming a medicane. Even though it is not yet clear whether Daniel can be entirely attributed to climate change, it is certain that these types of weather extremes will hit harder due to warming. In its latest series of reports, the IPCC, the United Nations scientific climate panel, concludes that medication may decrease slightly in number, but not in severity.
Storms like Daniel are fueled by the increasingly warmer sea water in the summer, Coumou says. With their spinning air and a windless eye, they are somewhat like the Atlantic hurricanes in the Caribbean and the United States – although they do not reach that enormous strength. “This summer the water in the Atlantic Ocean is extremely warm,” said Coumou. As a result, we have seen bizarre heat waves in the US, in China and also in the Mediterranean. Because the heat of the water is in the system and that drives the extremes.” It ultimately gave Daniel the opportunity to grow into such a deadly storm.
Inadequate infrastructure
Yet it would be too simplistic to point to climate change as the sole cause of the dramatic events in Libya. Just as important is how the country deals with the increasing risks of climate change. After the Paris climate agreement, almost all countries in the world submitted a climate strategy to the United Nations, Libya is one of the few exceptions. According to the Carnegie Endowment for International Peace the country is rapidly depleting its water supplythe infrastructure has long been unable to cope with the increasing extremes, and the country’s income is largely dependent on oil extraction, which is carried out in a rather reckless and polluting manner.
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In such a situation, climate change acts as a catalyst that can painfully expose society’s weaknesses. “This storm hit the country at an extremely vulnerable time,” says Coumou. “That has led to the enormous drama we are seeing now. It is a sum of inadequate infrastructure, lack of care for people and lack of a early warming system. A lot of misery could have been prevented if people had been warned in time.”
A lot of misery could have been prevented if people had been warned in time
Dim Coumou professor of weather extremes
In addition to being old, the infrastructure in Libya is also not designed to handle such large amounts of water. This is not surprising in a country that is known as extremely dry. The hardest-hit city of Derna is located at the end of a so-called wadi, a riverbed that only occasionally drains water. Before Daniel released his water over Libya, the wadi was completely dry. The valley through which the wadi passes had also dried out. If a large amount of precipitation falls in a short time, it is not easily absorbed into the hard soil, but the water flows very quickly towards the coast.
It is a risk that they know all too well in Libya, and certainly in Derna. The city has repeatedly suffered from flooding, including a very heavy one in 1959 and then in 1968. It was the reason for a Yugoslavian company to have two dams built in the wadi in the 1970s. One with a capacity of 1.5 million cubic meters, and a second, closer to the city, which could accommodate 22.5 million cubic meters.
Narrow funnel
Storm Daniel has been fatal for the dams. British earth scientist Dave Petley, an expert on landslides, does not rule out that they were not designed for such large amounts of water in such a short time. According to him, they could also have collapsed due to poor maintenance. Petley suspects that after the collapse of the smaller dam, such a large amount of water and sediment suddenly arrived at the second dam that it could not possibly withstand the pressure.
The second dam is only a kilometer from the city, when it broke the water was pushed with so much force into a narrow funnel, with houses right along the water and with many bridges, that everything was swept away in a devastating stream. There was insufficient time for the residents to find a safe haven.
Warn in time
The World Meteorological Organization (WMO) is working with other UN agencies on a global system to warn people in time when a storm is approaching. “In India and Bangladesh you see that this works,” says Dim Coumou, although this does not prevent material damage. “Cyclones often cost thousands of lives in those countries in the past. Now the number of victims remains very limited.”
Libya is still a long way from that. According to the WMO, the Libyan National Meteorological Center issued a warning of extreme weather 72 hours before Daniel made landfall. An email to a large number of government agencies urged preventive measures. In some eastern regions this led to a state of emergency being declared, but without a further evacuation plan this had little effect. “That is the painful conclusion,” says Coumou. “This disaster might have been prevented.”