In the Sahel, the extreme heat wave is indeed due to climate change

At this level of heat, every tenth of a degree is an additional ordeal. On April 3, the town of Kayes, in western Mali, posted a temperature of 48.5°C at the end of the day, according to the National Meteorological Agency, beating the previous continental record (48.3°C). C) recorded in the town of Karima, on the banks of the Nile, in Sudan, in 2003. This surge in mercury is the most spectacular manifestation of the extreme heat wave which is hitting the Sahel and all of West Africa since the end of March. If this time of year marks the start of the hot season, the readings taken almost everywhere in the area – with average values ​​sometimes higher than 45°C – are abnormally high.

What is the cause ? Only climate change can explain such a situation, says the study published Thursday April 18 by the World Weather Attribution (WWA). This network of scientists created in 2014 examines the links between the multiplication of extreme climatic events (droughts, storms, etc.) and the warming of the atmosphere linked to the use of fossil fuels. “This heat wave would not have been possible without climate change,” he assures, focusing his analysis on data from the five hottest consecutive days observed between March 31 and April 4 in southern Mali but also in neighboring Burkina Faso, where extreme temperature peaks also occurred. .

To arrive at this observation, scientists used climate models to compare the data recorded in the current climate, marked by an average increase in global temperature of 1.2°C, and what they would have been in the colder climate of the pre-industrial era. According to their results, in southern Mali and Burkina Faso, maximum temperatures during the day increased by 1.5°C due to warming and 2°C at night, creating conditions that were difficult to bear for the most vulnerable. The persistence of nighttime temperatures exceeding 30°C prevents the body from resting and recovering, causing a real danger to health, the authors insist to justify the importance of this monitoring.

The probability of a heat wave of this intensity occurring is estimated at once every 200 years, the study specifies. In the scenario of global warming of 2°C – a highly probable hypothesis – its frequency would be multiplied by ten, with extreme temperatures even 1°C higher. Climatologists also carried out this attribution exercise in other countries located entirely or partly in the Sahelian strip, such as Mauritania, Senegal, Niger, Nigeria or Benin – where abnormally high temperatures, although lower than those of Burkina Faso and Mali were also observed. The responsibility for climate change remains pointed out.

Excess mortality

The study, however, only establishes a very marginal link between the Sahelian heatwave and the ongoing natural climatic phenomenon El Nino, the effects of which on southern Africa are, conversely, clearly identified.

These extreme heat conditions are the cause of excess mortality – difficult to quantify precisely – even among populations accustomed to arid climates. At the beginning of April, the Gabriel-Touré hospital center in Bamako warned of the increase in deaths of people aged over 60, mostly suffering from chronic illnesses: 100 admissions followed by deaths were recorded between 1^er and April 4, almost as many as during the entire month of April 2023. In Mali and Burkina Faso, due in particular to ongoing conflicts, several million people are in a humanitarian emergency situation and are all the more vulnerable to climate change.

“The heat that rages all year round is part of life in the Sahel. However, extreme temperatures have been unprecedented in many places. To some, a heatwave 1.4°C or 1.5°C hotter due to climate change may not seem like a significant increase. But this extra heat meant the difference between life and death for many people,” underlines Kiswendsida Guigma, from the Red Cross and Red Crescent Climate Center in Burkina Faso, who participated in the study.

The work carried out by the WWA aims to raise awareness of the impact of uncontrolled combustion of fossil fuels, but it could also be used in discussions on financing adaptation to climate change between industrialized nations and countries the poorest, particularly Africans, whose responsibility for global warming is insignificant.

However, the budgets necessary to deal with the consequences of droughts or floods continue to increase. “The cost of climate disasters has doubled in the poorest countries over the past decade, according to World Bank calculations published Monday. Economic losses attributable to climate represent on average 1.3% of GDP per year, four times the average for other emerging economies. »