April heat points to scorching summer
Extreme weather will affect human health, agriculture and fishing, experts say
Temperatures across much of Japan soared to unseasonably high levels over the weekend, with the country’s meteorological agency warning of another scorching summer.
As extreme weather becomes more frequent, environmental experts say hotter and drier conditions threaten a range of sectors, from agriculture to fishing, with knock-on effects for human health and worsening habitat destruction.
“Japan has a rapidly ageing population, and it is this sector of society that will be hardest hit by high temperatures and humidity,” said Rajib Shaw, a professor at Keio University’s graduate school of media and governance who specialises in climate change adaptation.
“To already see 27 degrees [Celsius] in April is very worrying, and there will certainly be an impact on human health.”
Thermometers in central Tokyo touched a high of 26.1 degrees on Saturday, a level| typically not seen in the city until mid-June. Several other cities across Japan similarly recorded unusually warm conditions for the time of year, with Sano in Tochigi prefecture, just north of Tokyo, the hottest at 27.9 degrees.
The Japan Meteorological Agency has blamed the elevated temperatures on a high-pressure system moving over the main island of Honshu, with Isesaki in
Gunma prefecture, central Japan, reporting a maximum temperature of 27.1 degrees and the city of Funabashi, east of Tokyo, experiencing 26.6 degrees. It would be even hotter over the summer, the agency said.
In late July last year, the agency issued a nationwide warning of “once-in-a-decade temperatures”, with spot highs nudging 40 degrees. The daytime temperature for July typically averages from 23 to 30 degrees at night, but both figures have been climbing in recent years.
Record highs were reported last summer in all but four of the nation’s 47 prefectures, with the heatwave linked to the El Nino phenomenon affecting ocean temperatures and weather systems in the Pacific.
This summer is on course to match those withering temperatures. In its predictions for the April-to-June quarter, the Japan Meteorological Agency said there was a 60 per cent likelihood of the southern twothirds of the nation experiencing above-normal temperatures, with the Tohoku region of northern Japan and Hokkaido having a 50 per cent likelihood of elevated temperatures.
In a separate report, the agency said the surface temperature of the ocean surrounding Japan had reached a record high between June and February for the third consecutive year. Ocean monitors in Sendai Bay, northeast Japan, recorded a surface temperature of 13.5 degrees in mid-March, 4 degrees higher than at the same point in 2023 and 6.3 degrees above the average.
“Sea surface temperatures were already high in the western Pacific and this is one of the main reasons why temperatures across Japan are already high this year,” said Yoshihiro Iijima, a climatology professor at Tokyo Metropolitan University.
“Rising sea temperatures are a long-term trend linked to changes in the Black Current that flows up the east coast of Japan.”
The Kuroshio (Black Current) is a warm ocean current that typically curves east into the Pacific after reaching the Boso peninsula, to the east of Tokyo. Since the spring of 2023, it has continued flowing north off the coast of the Tohoku region, bringing warmer weather and species of fish commonly found in southern Japan.
“The current coming this close to the coast is likely to intensify annual temperatures and, combined with global warming, means that we can expect to see the development of more and more powerful anticyclone weather systems over Japan and East Asia,” he said.
In addition to the dangers to Japan’s elderly population, higher temperatures could also harm agriculture and fishing industries and exacerbate natural disasters, Keio University’s Shaw said.
The higher possibility of natural disasters linked to climate change was another serious concern. More frequent and powerful storms threatened to dump greater amounts of rain, leading to flooding, he said.