Strong heat then torrential rain, Belgium is experiencing extreme weather: “There is a very challenging parameter”

Strong heat then torrential rain, Belgium is experiencing extreme weather: “There is a very challenging parameter”

Last weekend, Belgium experienced major heat waves. An unusual phenomenon so early in the year. This weekend, the MRI announces a climate opposite to what we experienced seven days ago. Heavy rain, hail, thunderstorms… all of Belgium is on yellow alert for bad weather. But how to explain such a difference? “The situation we experienced this Thursday is not abnormal. The current storms are something quite common. On the other hand, the high temperatures of last weekend are quite exceptional”, comments Pascal Mormal at the microphones of La Première. For the IRM meteorologist, global warming plays a key role in these situations. “These high temperatures have already occurred once in 1996 (32.6° in Uccle). But since 1980, we have noticed that global warming has had effects. Previously, these were isolated events. For 30 years , there is a repetition and intensification of heat wave phenomena.

Pascal Mormal carefully observes these different trends. But one of them worries him more than another. “There is a very striking parameter: heat waves. When we analyze our statistical series, between 1892 and 1990, we experience these waves approximately every four years. Since 1990, we have experienced… 20 in 30 year !” Another element to take into consideration: cold spells. “During the first century of observation, we experienced more or less the same number of heat and cold waves. In the last thirty years, we have only experienced two cold waves. This evolution is very impressive”he admits.

Can we therefore speak of climate change? For the climatologist, this tends in this direction. “In Uccle, a station that is quite representative of Belgium, we have seen an increase of 1.2° in thirty years. This figure represents half since the beginning of the industrial era, i.e. 1850 in only a third century. Which is really considerable.” Pascal Moral also believes that the notion of season is less and less marked. “Indeed, the summer is getting longer and longer. And the winter is getting shorter and shorter. From now on, we can experience strong heat from May or June. And they can extend until September. last year, it was more than 34° in mid-September for example. In the opposite direction, we experience very few cold spells. Except for last February, it has been a good ten years since we last better known about this phenomenon.

For Belgians, it also means a warmer summer with more sunshine and rising mercury. Not enough to make them sad from day to day. “Obviously, there are positive sides for the population. What I can say is that it is necessary to take advantage of it… but not to rejoice too much. The most alarmist forecast models predict a rise of 4 to 5 degrees temperatures at the end of the century. I hope we don’t reach such peaks because that would mean that we have entered another world.”

Last year, Belgium also experienced torrential rains which fell particularly in the Province of Liège. “It’s the face of the same coin. When we talk about climate change, we automatically think of a heat wave. Instead of being faced with an anticyclonic phenomenon, we experienced a low pressure phenomenon. With in particular this famous cold drop. Throughout the summer, we had poor weather. And the climax of this situation was the floods in mid-July. We were helpless because we had never experienced such an extreme phenomenon in Belgium.”

This resulted in two and a half months of rain in just 48 hours. If this type of extreme phenomenon were to happen again, could Belgium cope? “We have learned lessons from this crisis. But faced with such a wild nature, we realize that we are very little.” The other question is what to expect this summer. “The risk of a major drought has been ruled out, as we have experienced heavy rains. This has limited the damage. For the moment, the signals tell us that we are going to experience a summer that is generally warmer than average and perhaps drier But I remain very careful because it changes very quickly and cold drops could reappear.”

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