The prolonged October heatwave in Madagascar would not have occurred without human-caused climate change, according to a rapid analysis by World Weather Attribution that is the first study to quantify the influence of climate change on a heatwave in Sub-Saharan Africa.
The heatwave was an extreme event that would have affected millions of people. However, like many heat events in Africa, the heatwave in Madagascar received almost no international attention and online reporting of heat-related impacts could not be identified by the authors of the study. The researchers say there is a low-level of awareness of the dangers of extreme heat in most of Africa and the lack of reporting of health impacts could make it harder for countries to negotiate access to climate finance.
Madagascar experienced its hottest October on record this year. Temperatures were more than 2.5°C above average, a heat which is normally not experienced until December or January. Antananarivo, the capital city in the Madagascar highlands and home to more than three million people, experienced some of the most intense and unusual heat.
It is well established that climate change is making heatwaves hotter and more frequent. To quantify the effect of climate change on the heatwave in Madagascar, scientists analysed weather data and model simulations to assess how the event has changed between today’s climate with approximately 1.2°C of global warming, with the cooler pre-industrial climate, following peer-reviewed methods.
The study looked at three variables to investigate the persistent heatwave: the October average temperatures over Madagascar, the seven-day maximum temperatures in Antananarivo and the seven-day minimum temperatures in Antananarivo. This latter metric refers to heat at nighttime, which can be dangerous for human health as the body does not have a chance to rest and recover.
The scientists found that the October heatwave over Madagascar and seven-day minimum temperatures in Antananarivo were at least 100 times more likely because of climate change and would have been virtually impossible in a 1.2°C cooler world without warming from the burning of fossil fuels. The seven-day maximum temperatures were at least 10 times more likely due to climate change.
Global warming caused by the burning of fossil fuels made the heat more intense than it would otherwise have been. The analysis found that human-caused climate change made the month-long heat, seven-day maximum temperatures and seven-day minimum temperatures about 1-2°C hotter.
In today’s climate, a hot October such as this year’s is still a relatively rare event. Such October temperatures in Madagascar can be expected approximately once every 100 years in the region, while the seven-day maximum temperatures and seven-day minimum temperatures in Antananarivo are expected to occur about once every 20-25 years.
However, if fossil fuels are not rapidly phased out these heat episodes will become much more frequent and extreme. If global warming reaches 2°C, similar October heatwaves in Madagascar and Antananarivo will become even more likely, occurring about twice a decade, and an additional 0.8°C hotter compared to today’s climate.
Despite the dangerous temperatures recorded in Madagascar, the researchers could not identify reported impacts associated with the heat. Extreme heat is underreported and understudied in most African countries, making it more difficult for governments to highlight ongoing climate impacts.
