Exactly a year ago, as October 2018 came to a close, an exceptional spell of extreme weather hit Italy from north to south. Overflowing rivers, mudslides, landslides and storm surges caused major damage and at least twelve deaths, at an estimated cost of almost three billion euro.
The most dramatic element of all this was the furious south wind which lashed the whole country. In the space of just a few hours, whole forests in the north-east were literally leveled by gusts reaching 200 kilometres per hour.
Something unprecedented had happened. As the measuring stations confirmed, the quantity of precipitation and wind speeds broke the historical records, and the overflowing rivers flooded areas which hadn’t been reached for decades. The exceptional nature of the event was all too clear to people on the ground: millions of trees dropped like toothpicks. In just a few hours, the landscape had changed entirely.
The affected regions had already experienced a long series of natural disasters, which had leveled entire woodland areas. However, even in 1966, with the great flood which brought Italy to its knees, ten times fewer trees were felled by wind.
Nevertheless, storms of this kind, while exceptional, aren’t exactly unfamiliar to Europe. Wind is the major source of damage to continental European forests (much more so than fire), with more than seventeen million cubic metres of trees blown down each year – a figure which, according to estimates , could double by 2050. The areas most affected are central-west Europe, especially the countries facing the Atlantic, and northern Europe.
In 1999 the “Christmas storms” Lothar and Martin caused unprecedented damage: 240 million cubic metres of woodland were flattened. France and Germany were the countries most affected, with 176 and 34 cubic metres destroyed, respectively. Direct victims numbered around 140, and at least one hundred people died the next year during the perilous restoration process. The timber market was ravaged, and the total damages amounted to over ten billion euro.
Taking a look at similar catastrophes, even storm Vaia in October 2018 pales in comparison. Storms of this kind strike only rarely on the southern side of the Alps. While one event is not enough to blame global warming, numerous studies indicate that storms in the future are likely to affect much larger areas, and coniferous forests (like those in the Alps) will be the most vulnerable.
If the storm hits the mountains
The massive damage to forests over the past year have had a particularly bad impact in eastern Trentino and Belluno. Mountainous regions are more fragile, and vulnerable to hydrogeological instability, especially in an era of climate change and depopulation.
Within the affected woodlands, more than forty percent of trees were completely leveled, mostly on the steep, high-altitude areas. These areas, once stripped of trees, are prone to avalanches and rockslides, sometimes close to inhabited areas, streets or other infrastructure. In the province of Trento alone, 280 sites are identified as at risk in the aftermath of Vaia, and this is without taking into account all the tricky and dangerous work involved in removing stumps and making these areas safe.