Could the death toll rise by another 451,000?

The Japan Meteorological Agency said on Friday that sea surface temperatures in the Pacific Ocean region it monitors for El Niño were 4.0°C above normal.

This is the highest reading since records began in 1949, surpassing the previous record of 3.6°C set in December 1997.

The agency expects temperatures to continue rising through the Northern Hemisphere winter, when the weather phenomenon is expected to reach record levels.

Meteorologists have been warning for months that this year's El Niño could be the strongest ever recorded, dubbing it a “super El Niño.”

What is El Niño?

El Niño is the warm phase of a natural cycle known as the El Niño–Southern Oscillation, a climate pattern that influences weather conditions around the world.

It tends to raise global temperatures and disrupt rainfall patterns across large regions, causing drought in some areas and heavy rainfall in others. It typically occurs every two to seven years.

Japan's warning comes after the World Meteorological Organization (WMO), the United Nations' weather agency, said on Thursday that El Niño would continue to intensify, reaching its peak around December.

“WMO forecasts indicate a nearly 100% probability that it will persist through February 2027, potentially making it one of the strongest events since 1949,” said Celeste Saulo, WMO Secretary-General.

451,000 additional deaths

Researchers at the University of Chicago's Climate Impact Lab estimated in a report last month that heat associated with the phenomenon could cause as many as 451,000 additional deaths worldwide between June and February 2027.

The Japanese laboratory also said that the number of extremely hot days is expected to increase by 44 percent compared with normal years, explaining that this figure is a projection based on modeled increases in extreme heat.