Japan lost a potential 2.2 billion labor hours due to extreme heat last year, rising 50% compared with the annual average in the 1990s and suffering a potential economic loss of $37.5 billion, according to the latest Lancet Countdown report, which was released this week.

Globally, heat-related deaths of elderly people increased at record levels that year, with Japan being among the most severely hit countries, according to the report, which tracks the impact of human-caused climate change on people’s health.

Last year saw Japan’s joint-hottest summer on record, with that degree of heat being matched again this year.

The annual report says the world is facing elevated threats in 10 of 15 health indicators, experiencing more heat-related deaths, increased transmission potential for the dengue disease and heightened food insecurity and undernutrition brought on by the greater frequency of heat waves and droughts.

“In 2023, people were exposed, on average, to an unprecedented 50 more days of health-threatening heat than expected without climate change, resulting in 167% more annual deaths of adults older than 65 years than in the 1990s,” the report says.

Moreover, the hours of sleep lost due to heat exposure in 2023 were 6% above the hours lost annually between 1986 and 2005. Heat exposure, meanwhile, led to record losses in the hours available for safe outdoor physical activity and labor, as well as the record worsening of people’s emotional states globally, the report points out.

At the same time, compared with the decade through 1960, the climate suitability for the transmission of dengue by Aedes albopictus, a mosquito species common in temperate regions including Japan, increased by 46.3% in the 2014-2023 period, while the suitability for Aedes aegypti, which typically breeds in tropical and subtropical regions, increased by 10.7% over the same period, the report says.

For Japan, the report estimates that, between 2014 and 2023, the total number of heat wave days experienced annually by children under age 1 was 2.4 times greater than the equivalent demographic between 1986 and 2005, while adults over age 65 experienced 4.7 times more heat wave days across the same time frame.

In terms of labor hours lost, construction workers were hit the hardest, seeing 35% of the potential hours lost and 41% of the potential income lost.

Dr. Takeo Fujiwara, a professor of public health at the Institute of Science Tokyo who was not directly involved in the Lancet report, said doctors in Japan should step up advocacy and education efforts.

“There is this mindset in Japan that climate change is happening somewhere far away,” he told a media briefing on Friday. “(But) no one can escape the health effects of climate change, unlike other health risks like tobacco smoking, where various risk reduction measures have been taken.

“The report emphasizes that, unless we change our heavy subsidies to fossil fuels, climate change will ultimately damage our health and disadvantage the world economy.”