Climate change has increased the likelihood of intense rains causing historic floods in Nigeria 80-fold, which in recent months have killed more than 600 people and devastated agriculture in Africa’s most populous country, a study finds science released Wednesday.
These extraordinary floods, which also affected Niger, Chad and neighboring countries, displaced more than 1.4 million people and ravaged hundreds of thousands of hectares of crops, in the midst of a food crisis linked to the war in Ukraine.
Main cause: exceptional rainfall levels in the region around Lake Chad, since the start of the rainy season in June.
However, “climate change caused by human activity has made this event about 80 times more likely and about 20% more intense,” concludes the World Weather Attribution (WWA), author of the report published on Wednesday.
A pioneer, this global network of scientists has established itself in recent years by its ability to quickly assess the link between extreme weather events and climate change, this link not being systematic.
Among its previous studies, the WWA concluded that last summer’s drought in the northern hemisphere was made “at least 20 times more likely” by global warming linked to greenhouse gases. Or that the 2021 heat wave in northwestern Canada and the United States would have been “virtually impossible” without climate change. But that it was not however the major factor of the food crisis in 2021 in Madagascar.
Their results, produced urgently and made public without going through peer-reviewed journals, are obtained by combining methods approved by their peers, primarily historical weather data and climate models.
In the Lake Chad region, the “above-average rainfall” recorded this year “now has about a one in ten chance of occurring each year” whereas they were extremely rare before the climatic impact of the use of fossil fuels, estimates the WWA.
Scientists also looked at the 7-day peak rainfall along the lower Niger basin in Nigeria. They conclude that “climate change made the event about twice as likely and about 5% more intense.”
Losses and damages
The publication of these conclusions comes in the midst of negotiations in Egypt at COP27, where developing countries are asking the rich, polluters since the beginning of the industrial era, to pay for the “losses and damages” linked to climate change.
“It’s not up to us scientists to tell the negotiators what to do. We are just presenting the evidence here”, but even at 1.2°C of global warming, “we are already seeing increases in risk”, underlined Maarten van Aalst, director of the International Red Cross Climate Centre, during of an online press conference.
“It also shows very clearly that these impacts are not future, they are happening today: so we need these financing solutions,” he added.
WWA researchers also looked at the drought that has worsened the ongoing food crisis for people in the Sahel in Burkina Faso, Chad, Mali, Niger and Nigeria. This shortage “came after an erratic rainy season in 2021, which affected agricultural production and reduced food stocks months later”, recalls the WWA.
“But scientists have found that the variability of rainfall in the region and the lack of historical weather data […] did not determine whether human-induced warming had played a role,” the network writes.
The researchers therefore consider it “essential to invest in weather stations” in the region, essential to help populations “highly vulnerable to extreme weather conditions”, whether or not they are attributable to climate change.