Japan faces 99 times more heatwaves if global warming intensifies, report warns

A new report reveals global warming could cause “once-in-a-century” heatwaves annually

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Young women use fans to seek relief from the heat in Tokyo. Japan’s weather agency says the country could face annual once-in-a-century heatwaves if global warming continues. Photo: AFP

Published: 9:30am, 29 Mar 2025Updated: 10:44am, 29 Mar 2025

Japan could experience once-in-a-century heatwaves every year if global warming spirals out of control, according to a warning from the country’s meteorological agency.

A report released on Wednesday indicated that the frequency of “centennial extreme temperatures” – hot days previously recorded only once per century – would occur 99 times per century in Japan if the global average temperature rises by 4 degrees Celsius. Under this scenario, these extreme temperatures would be nearly 6 degrees higher than pre-industrial levels.

The report, titled “Climate Change in Japan 2025,” was co-authored by the Japan Meteorological Agency and the Ministry of Education, Culture, Sports, Science, and Technology.

It builds on a similar study conducted in 2020 and shows that the average temperature in Japan is increasing at a rate of 1.4 degrees per century from 1898 to 2024.

The report highlighted the rising number of “extremely hot days,” defined as those with maximum temperatures of 35 degrees Celsius, and “true summer days,” with maximum temperatures exceeding 30 degrees.

Two extreme temperature events in Japan, which occurred in July 2018 and July 2023, would not have happened without global warming, the report said, underscoring global warming’s effect on frequency and intensity of extreme weather events.

The report also stated, if the global average temperature were to increase by 4 degrees, Japan would experience an additional 17.5 “extremely hot days” each year and 46.2 fewer days with minimum temperatures dropping below zero.