The likelihood of a heatwave lasting 12 consecutive days, such as the one we have just experienced, is almost five times greater in Belgium than it was in the 1980s research by climate scientists at the Flemish Institute for Technological Research (VITO) shows. Such extreme heatwaves now occur once every seven years.
A heatwave lasting 12 consecutive days, such as the one that ended on Monday, is extremely rare. Since 1975, only seven heatwaves lasting at least 12 days have been recorded at the Met Office in Ukkel (Brussels). However, according to the team of climate scientists at VITO, we can expect these to become increasingly common in the near future.
Possible scenarios
The scientists calculated the probability of such prolonged heatwaves occurring in Belgium. In the 1980s, that probability was a mere 3 per cent per year. It has now increased almost by a factor of five to 14 per cent per year.
Between 1975 and 2026, there were seven prolonged heatwaves, four of which occurred in the last 23 years. That is an average of once every seven years, whereas in the 1980s the average was once every 30 years.
What is a heatwave?
The Royal Meteorological Institute (RMI) defines a heatwave as a period during which a maximum temperature of 25 degrees Celsius is recorded in Ukkel for five consecutive days, three of which are above 30 degrees.
What about the future?
The projections for the situation in 2030 vary somewhat.
According to the most optimistic scenario, the frequency of lengthy heatwaves will stabilise after 2060 to once every four years. The most pessimistic scenario suggests that we can expect a lengthy heatwave every two to three years.
What can we do?
“If we want to reduce the risks posed by increasing heatwaves, we need to take action in two areas,” says climate researcher Hendrik Wouters of VITO.
Firstly, we must reduce greenhouse gas emissions by focusing on renewable energy, drive less using fossil fuels and make industry more sustainable.
At the same time, we must also adapt to the inevitable rise in temperatures. This means more green spaces and shaded areas in cities, building regulations that take higher temperatures into account, and effective heatwave plans to protect vulnerable members of society.
According to Wouters, most buildings are currently still constructed without taking the summer heat into account. Investing in smart insulation, sun protection and passive cooling is crucial to keeping us cool in the future without using more electricity.
The heat is particularly relentless in the major cities. That is why, according to Wouters, it is crucial to make cities more heat-resilient. “Smart urban management – with the right tree species in the right places, permeable pavements and cool public squares – can make all the difference for residents,” he says.