Several French temperature records were broken on 28 June during this historic heatwave, including the highest temperature ever recorded in the country since records began – 45.9C. The previous high was set during the 2003 heatwave, which was the most significant episode in France’s meteorological history until now.
Saharan air has engulfed the country. On 20 June, while meteorologists were discussing the projections of the American global forecast system model, a map with a disturbing resemblance to Munch’s painting The Scream came to my attention. Within a few days, the media spotted this comparison and the image went viral. In 15 years of model observation I had never seen such high temperatures predicted for France, especially in June. The forecast, made more than a week in advance, proved correct: records were not just broken, they were smashed.
But summer still has a long way to go, and the fact that temperatures have risen so much so early in the season is not reassuring. With a pre-industrial climate, the probability of an episode such as the 2003 (and now the 2019) heatwave was less than 1 in 100 according to climate models. Today, the same risk is 25%. If we reach an increase in global temperatures of 1.5C the chance will rise to 40%; at +2C it will be more than 60%.
At the same time, the probability of events colder than normal in both summer and winter is decreasing. When a heatwave occurs, physical processes trigger its continuation: less ground humidity, increasingly high energy flows and increasingly hotter air masses, even at altitude. Thus we observed temperatures of up to 7C at the top of Mont Blanc, at 4,800m, which is 14C above seasonal norms.
The 2003 heatwave could have been a European trigger for global action against the climate crisis. During the very high temperatures 16 years ago, more effective health responses were put in place to limit the number of deaths were such a phenomenon to recur. But that was all. We cannot make that mistake again. The 2019 heatwave should be a warning to us: as scientists have been warning for decades, it is time for a Europe-wide response to fight the climate crisis.
We must come up with a better plan for how to deal with these heatwaves. Even if we limit the current warming to +2C, our continent will experience heatwaves as intense, and even more intense, than the one we have just lived through far more frequently. Our societies will not be able to get through such violent episodes without significant damage.
• Ruben Hallali is a French meteorologist and founder of HD Rain