This story was originally published by the Guardian and is reproduced here as part of the Climate Desk collaboration.

More than 450,000 people are projected to die from the additional heat brought by the super El Niño by February, according to estimates by climate scientists.

The toll is on top of the early deaths resulting from temperatures already driven up by the climate crisis. It will strike across the globe, from Indonesia to India, and Nigeria to the United States. Many further deaths are expected from the droughts, wildfires, and flooding that El Niños bring.

The heat deaths have been estimated at regional level, and the researchers said the projections therefore identified where measures to protect people could be put in place and save lives. Such actions could include better heat forecasts, cooling centers where people can shelter, increased staffing for medical facilities at the hottest times and protections for outdoor workers.

The El Niño currently heating up the planet burst through the highest temperature ever recorded for the phenomenon on Monday, several months before its expected peak. The heat is so much greater than previous events that scientists have called it “mind-blowing” and “Godzilla-level.” El Niños are natural climate events but may be made worse by global heating.

A major El Niño in 1877-1878 led to more than 50 million deaths due to drought and famine.

“The estimate of 451,000 people is such a large number that it can be numbing, but it is made up of parents and children, grandparents and neighbours, people going to work, caring for families, and living their lives,” said Michael Greenstone, co-founder of the Climate Impact Lab and a professor at the University of Chicago, who co-authored the report.

The estimate of deaths is for the period June 2026—as some heat deaths will have already occurred—to February 2027, which is when current temperature forecasts end. But elevated levels of heat deaths are expected to continue until June or July 2027.

The most affected countries in the next six months are the tropical nations of Nigeria, Indonesia, Sudan, India, and Brazil. The US is in the top 20 most affected nations, with 3,500 projected additional heat deaths. More broadly, the Sahel region in Africa and Southeast Asia are heavily affected.

The El Niño is also a “postcard from our future,” the researchers said, pushing up temperatures to the level the climate crisis is projected to deliver in 20 years.

“Increasing emergency response and better targeting our efforts can save many lives this year,” said report co-author Tamma Carleton at the University of California, Berkeley. “But 20 years from now, once today’s extreme temperatures become the new normal, we don’t want to be in a constant state of emergency… We need to mobilize now to design, deploy, and evaluate the tools that will save lives in the years ahead.”

The projections were made using peer-reviewed methods that track the month-by-month relationship between temperature and additional heat deaths in 24,378 regions across the world. This was combined with the forecasts for higher temperatures due to El Niño in the months ahead. The baseline was the number of heat deaths in the average month from 1996 to 2025.

“People have been able to forecast when there’s going to be shocks to crops, and give advance warning of that,” said Greenstone. “This new report is opening the door to being able to do it for an even more important outcome—I would say the most important outcome—which is death.” The report will be submitted to a peer-reviewed journal, but Greenstone said that, given the urgency of the situation, “it would have been irresponsible to sit on it.”

Food supplies will also be hit by El Niño, with the World Food Programme warning in August that its impacts were likely to push about 50 million people into acute hunger and drive prices up. A major El Niño in 1877-1878 led to more than 50 million deaths due to drought and famine, with India, Brazil, and China severely affected.

Friederike Otto, a professor at Imperial College London, told The Guardian on Monday: “The [current El Niño] event is a huge redistribution of energy in the climate system and is dangerous, because it is unfolding on top of a much warmer, human-influenced climate system.”

“So, he continued, “in many places around the world we will see never-before-experienced heat extremes, with all their consequences on health, food security and water stress. El Niño comes and goes, but as long as we continue to burn fossil fuels, it occurs on an increasingly hotter baseline, making it much more difficult for communities to deal with the consequences.”