According to a report published in the scientific journal Nature, climate researchers in France are of the opinion that rising summer temperatures could increasingly negatively affect Tour de France cyclists in the future.
According to a report by researchers at the National Research Institute for Sustainable Development at the University of Montpellier, the Tour's organizers have so far managed to avoid France's most severe heat, but they warn that more frequent and higher peak summer temperatures are creating health risks for both the race and spectators.
"Our analysis shows that, for example, Paris has exceeded the high-risk threshold for heat in July five times, four of which have occurred since 2014," said lead author Ivana Cvijanovic. "Other cities have had many days of extreme heat in July, but fortunately not on the date of a Tour stage."
Yes, transporting equipment and setting up the start and finish areas would be logistically more complex, cyclists would have to eat breakfast earlier, and the race would not be broadcast during prime time for television viewers. But if the weather becomes such that athletes and spectators cannot survive a stage safely, it may be time to consider other solutions.
The Union Cycliste Internationale (UCI) established an extreme weather protocol in 2015 using the same metrics as the study's authors, but it has rarely been implemented due to high heat.
In 2022, the protocol was applied during stage 15 of the Tour – a grueling 202.5 km ride on melting asphalt roads from Rodez to Carcassonne, when forecasts predicted air temperatures of up to 40 degrees Celsius. The only changes were the earlier opening of feeding stations and an extension of the time limit. Although there have since been several stages where cyclists have coped with the heat by dousing themselves with ice socks and cold water, no stages have been cancelled due to heat in the Tour at least – but it is only a matter of time before it becomes necessary.
"In a sense, you could say it is an extraordinarily lucky race, but record heatwaves are becoming more frequent, and it is only a matter of time before the Tour encounters a day of extreme heat stress that will put existing safety protocols to a serious test," said Cvijanovic.
Her team studied the so-called wet-bulb globe temperature (WBGT – an index that accounts for air temperature, relative humidity, solar radiation, and wind) at different times of the day in July across six regions of France between 1974 and 2023.
They found that in five out of six regions, the highest historical WBGT at 3 PM has been measured since 2018, and days of "high heat stress" (according to the threshold of the UCI's extreme weather protocol) have become more frequent and intense in recent decades.
Furthermore, regions where Tour stages frequently take place – such as Toulouse, Pau, Bordeaux, Perpignan, and Nîmes – have experienced episodes of high heat stress. "New heat stress hotspots are emerging: for example, Paris and regions in Central France are increasingly exceeding the UCI's high-risk WBGT threshold of 28 degrees," the authors write. "The morning hours are the safest part of the day, while high heat stress can persist for most of the afternoon. Scheduling the race in the morning and avoiding the afternoons would significantly increase the safety of cyclists and spectators. Mountain regions remain (for now) predominantly within low or moderately low-risk WBGT values throughout the day."
Although most professional cyclists are accustomed to pushing themselves under high load in summer heat, conditions become dangerous when the air temperature rises above body temperature. At this level, cyclists and spectators can no longer cool themselves through sweating, which can lead to a rise in body temperature, heat exhaustion, or heatstroke – the latter of which can be fatal.
If climate studies are accurate, extreme heat will sooner or later reach the Tour as well, and the authors believe it is time to consider changing the current organizational scheme and moving the race to an earlier time. If stages start around 12 PM and end around 5 PM, it means cyclists are racing for the majority of the stage during the hottest part of the day. Moving the start to, for example, 9 AM would significantly reduce this.
"We reiterate all these recommendations and suggest continuing the development and reassessment of hot weather emergency protocols for future editions of the Tour de France," the authors added.