Once-in-100 year temperatures in Sahel, West Africa impossible without man-made warming, study finds


April 18 (UPI) -- An extreme once-in-a-century heat wave in Africa's Sahel and western regions that saw temperatures soar to as high as 48.5 degrees Celsius at the end of March and early April was caused by human-induced climate change, an international climate study group said Thursday.

The extreme weather event, which saw Mali post its highest ever temperature, highs above 45 degrees Celsius in the Sahel but also severe heat in Senegal, Guinea, Burkina Faso, Niger, Nigeria and Chad, coincided with power cuts and people fasting for Ramadan to create deadly conditions for the populations of the affected countries, World Weather Attribution said in its report.

Significantly, conditions were exacerbated by elevated minimum and night-time temperatures, which normally offer some respite, remaining relatively high.

The Gabriel Toure hospital in the Mali capital, Bamako, recorded 102 deaths, half of them among people 60 and older from April 1-4 at the height of the heat wave, compared with 130 deaths for the whole of April 2023, with 44 burials at a single cemetery in the city on April 5.

WWA said that while information on the causes of death was not yet available, the hospital had indicated that heat likely played a role in many of the deaths.

Using climate models in combination with observations, the scientific team from Mali, Burkina Faso, Mozambique, the Netherlands, Sweden, the United States and Britain were able to show that the 1.2 degrees Celsius of global warming that has already occurred due to human activity was the cause of the extreme temperatures.

"Heat waves with the magnitude observed in March and April 2024 in the region would have been impossible to occur without the global warming of 1.2 degrees Celsius to date. Extreme 5-day maximum heat as rare as the observed event over Mali/Burkina Faso would have been 1.5 degrees Celsius cooler and 1.4 degrees Celsius cooler over the larger Sahel region if humans had not warmed the planet by burning fossil fuels," the report said.

"For minimum temperatures over Mali/Burkina Faso the change in intensity is even larger: in a 1.2 degrees Celsius cooler climate the nighttime temperatures would have been 2 degrees Celsius cooler," WWA said warning that future warming would intensify the heat trends.

The rare heat wave experienced by Mali and Burkina Faso would be 1 degree Celsius hotter when global warming reaches 2 degrees Celsius above the pre-industrial era and 10-times more frequent than in today's climate.

The team said they had taken the warming effect of the El Nino oceanic weather system in to account but had found only a small influence compared to human-induced climate change, contributing about 0.2 degrees Celsius of the observed 5-day heat event.

They also found rapid urbanization and loss of green spaces in major population centers like Bamako and Ouagadougou had contributed by amplifying a so-called "urban heat island effect" and called for both immediate and longer-term structural changes in Mali and Burkina Faso to mitigate the impacts of extreme temperatures.

"Coupled with high vulnerability, this highlights the need for sustainable urban planning that integrates green spaces, and building designs that account for high temperatures," the report argued.

"Critical infrastructure such as electricity, water, and healthcare systems needs to be strengthened to adapt to the increasing frequency and intensity of extreme heat, requiring increased investment to ensure reliable access and service delivery."

The WWA study comes four weeks after the United Nations identified the Sahel as a water scarcity "hot zone" that posed a threat to global security amid rising tensions and an uptick in disputes in the semi-arid region over water and productive land due to water loss through wetland degradation from ill-advised water development projects and climate change.

The U.N.'s World Water Development Report 2024 urged the settling of conflict over access to water in African and Middle East "hot zones" through greater international cooperation and transnational agreements, warning that brewing hostility over the scarce resource threatened world peace.

The extreme African heat event also comes on the heels of the European Union's Copernicus Climate Change Service reporting that March was the warmest ever March in modern times and the tenth straight temperature record-breaking month.

The global average recorded was a record 1.68 degrees Celsius higher, calculated from an estimate of the average March temperature during the "pre-industrial" reference period, designated as 1850-1900. The calculation also showed the temperature in the April 2023 to March 2024 period was 1.58 degrees Celsius higher than the pre-industrial average, Copernicus said in an air temperature climate bulletin.

Globally, the temperature in March averaged 14.14 degrees Celsius, 0.73 degrees Celsius higher than the 1991-2020 average for March and 0.10 degrees Celsius above the previous high set in March 2016.