As Japan's summers have become hotter and more humid than in the past due to climate change, an estimated loss of about 2.9 billion hours of labor time per year has occurred.
On the 5th, Nihon Keizai Shimbun reported, based on data from the U.S. National Oceanic and Atmospheric Administration (NOAA) and other sources analyzing the climates of major cities around the world from 2020 to last year, that Tokyo's maximum temperatures and humidity in July–August were at levels similar to Bangkok, Thailand, or Singapore.
According to Nikkei, Tokyo's temperatures and humidity in July–August both rose compared with the 2000s and the 2010s. The "tropicalization" phenomenon, in which Japan's summer is changing into a hot and humid climate similar to major cities in Southeast Asia, has become pronounced.
In hot and humid weather, the human body's thermoregulation function is prone to decline. This leads to reduced work efficiency for workers and, ultimately, the expense of climate change can appear as a loss of productivity.
The British international journal The Lancet estimated the hours of decreased work efficiency due to heat based on labor intensity by industry and the number of employed persons, and found that Japan's per capita labor time loss in 2024 totaled 43 hours a year. Based on an eight-hour workday, that exceeds five days.
Converted to all workers in Japan, the loss reached 2,890,820,000 hours. Compared with the average annual loss of 1,427,710,000 hours in the 2010s, it doubled.
Labor losses due to extreme heat are not unique to Japan. In China, where many are employed in agriculture and construction, the per capita labor time loss in 2024 was 96 hours a year, more than double Japan's. Globally, the potential economic loss from extreme heat was estimated at $1 trillion.
Countries are hurrying to prepare countermeasures such as rules to restrict work during heat waves. Japan also revised its Industrial Safety and Health Regulations last year, making it mandatory for employers to establish a reporting system and emergency response procedures when heatstroke occurs at worksites where heatstroke is a concern and to inform workers of them.
However, despite institutional improvements, damage at industrial sites is growing. According to Japan's Ministry of Health, Labor and Welfare, the number of casualties from heatstroke at industrial sites last year was 1,681, up 40% from the previous year, the highest since related statistics began to be compiled in 2005.