In late March and early this April, extreme heat impacted countries in the Sahel and West Africa. The hottest temperature occurred on April 3, when Mali recorded 48.5°C. In Bamako, the Gabriel-Toure Hospital announced a surge in excess deaths, with 102 deaths over the first four days of April.
Around half were over the age of 60 and the hospital reports that heat likely played a role in many of the deaths. A lack of data in the countries affected makes it impossible to know how many people were killed, however it’s likely there were hundreds or possibly thousands of other heat-related deaths.
Climate change, caused by burning fossil fuels like oil, coal and gas, and other human activities, is making heatwaves more frequent, longer and hotter around the world. To quantify the effect of human-caused warming on the extreme temperatures in the Sahel and West Africa, scientists analysed weather data and climate models to compare how these types of events have changed between today’s climate, with approximately 1.2°C of global warming, and the cooler pre-industrial climate using peer-reviewed methods.
The analysis looked at the five-day average of maximum daily temperatures in two areas: one that includes southern regions of Mali and Burkina Faso, where the heat was most extreme, and a larger area including regions of Niger, Nigeria, Benin, Togo, Ghana, Côte d'Ivoire, Mauritania, Senegal, Gambia, Guinea-Bissau and Guinea, where temperatures were widely above 40°C.
To investigate hot night time temperatures, which can be dangerous when the human body cannot rest and recover, the researchers also analysed the five-day average of minimum temperatures for the Mali and Burkina Faso region.
The scientists found that both the daytime and nighttime heatwaves, across both regions, would have been impossible if humans had not warmed the planet by burning fossil fuels like oil, coal and gas, and with other activities like deforestation. Climate change made the maximum temperatures 1.5°C hotter and the nighttime temperatures 2°C hotter for the Burkina Faso and Mali region, and the five-day daytime temperatures for the wider region 1.4°C hotter.
A heatwave like the recent one is still relatively rare, even in today’s climate with 1.2°C of warming, the researchers found. Across the wider West Africa region, similarly high daytime temperatures can be expected about once every 30 years. However, daytime temperatures like those experienced in Mali and Burkina Faso, where heat-related fatalities were reported, are expected around once in every 200 years.
But events like these will become much more common, and even more dangerous, unless the world moves away from fossil fuels and countries rapidly reduce emissions to net zero. If global warming reaches 2°C, as is expected to occur in the 2040s or 2050s unless emissions are rapidly halted, similar events will occur 10 times more frequently.
The researchers also quantified the possible influence of El Niño on the heat, but found that its effect was not significant when compared with the influence of human-caused climate change.
The study highlights factors that worsened the impacts of the heat across the region. The heat occurred at the end of Ramadan when many Muslim people fast during the day. The Sahel region has a large Muslim population and while high temperatures are common in April, the researchers say the relentless day and nighttime heat would have been overwhelming for many people who were abstaining from food and water.
They also note that conflict, poverty, limited access to safe drinking water, rapid urbanisation and strained health systems likely worsened the impacts.
Heat action plans that set out emergency responses to dangerous heat are extremely effective at reducing heat-related deaths during heatwaves. However, neither Burkina Faso nor Mali has one in place. Given the increasing risk of dangerous heat in the Sahel and West Africa, the researchers say developing heat action plans will help to save lives and lessen the burden of extreme heat on health systems.
A Guest Editorial