Climate Impact Lab projects 451,000 extra El Niño heat deaths by February 2027

The projection's control is a calendar average. The Climate Impact Lab compares expected heat-related deaths with the average for the same months in 1996-2025 ^[4]. Every death in its total is therefore an excess over the past 30 years of the same season. Heat deaths that an ordinary year would bring are already inside that baseline ^[4].

The design has two stages. First, the team took the European Centre for Medium-Range Weather Forecasts' seasonal forecast of how far temperatures will depart from normal over the next six months ^[3]. Then it converted those departures into deaths using the lab's peer-reviewed research, which estimates how temperature changes death rates in 24,378 regions ^[3][5]. Those estimates account for local climate, people's risk and their ability to cope with heat ^[5]. In the model, the same anomaly produces more deaths in a poorer place than in a wealthier one ^[9].

For the Sahel, the forecast drives the result. "Some of the largest temperature anomalies across the globe over the next six months will be across the Sahel, which is why the region faces greater impacts from the super El Niño than other regions," said Michael Greenstone, one of the four researchers ^[8][2]. Nigeria, Sudan, Niger and Chad together make up about 15% of the global projection ^[1]. Nigeria alone accounts for 47% of the four-country total ^[2]. Spread over Nigeria's 237.5 million residents, its projected toll comes to roughly 13 extra deaths per 100,000 people for the season ^[3]. The four country figures sum to 66,900, which is 100 more than the published group total. A gap that size is consistent with rounding ^[4].

The researchers set those numbers beside poverty and power data. More than 60% of Nigerians lived below the national poverty line in 2025, and even homes with electricity face power cuts ^[11]. In Sudan, where war has damaged power supplies, an estimated 57% of people lived in extreme poverty in 2025 ^[12].

The thing this doesn't tell you is how confident to be. The figures are published as point estimates, such as the 451,000 ^[1], with no uncertainty range attached. Each one stacks a mortality model on a six-month forecast, so any error in the forecast carries straight into the death count. A health ministry also cannot wait for the forecast to be checked. The months the forecast covers are the months in which the projected deaths would occur ^[6].

"While our study did not directly address who is most at risk, there is already a large body of research on who is most affected by heat," Greenstone said ^[13]. That research points to people over 65, children up to age four and people with chronic health conditions ^[14]. In Africa, it adds outdoor workers such as farmers, and anyone without indoor cooling ^[15].