This summer, which saw weeks of sweltering, dangerous heat across Japan, has been the hottest on record, Japan’s weather agency said. The abnormal heat, which shot to above 40 degrees Celsius in several places, has caused thousands of cases of heatstroke and damaged industries, including agriculture and fisheries.
The Meteorological Agency says the average temperature in Japan from June to August was 1.76 degrees Celsius higher than usual, tying with last summer for the hottest since modern record-keeping began in 1898.
On one day in July, the mercury surged to a crushing 40 degrees or higher in six different places.
An agency expert panel termed the heat from July on as “abnormal.”
The experts said Japan was covered by a tall and warm high-pressure system as westerly winds meandered northward. They also said the Pacific high pressure system expanded toward western Japan particularly in July.
University of Tokyo Professor Nakamura Hisashi, who heads the Meteorological Agency expert panel, said it cannot be denied that long-term global warming is raising temperatures. He warned that the hot weather may continue.
Agriculture and fisheries suffering
The record-breaking heat is starting to affect autumn delicacies.
Kyoho, a famous variety of large grape ― in this case grown in the city of Matsudo in Chiba Prefecture ― is one victim.
Kyoho is known for its deep-purple skin, but the grapes on the vine here are still greenish, the scorching heat delaying their coloring.
The farmer says Kyoho start darkening when nighttime temperatures are about 20 to 25 degrees Celsius. But he is having trouble this year because the temperature at night has remained around 30 degrees in recent days.
The orchard normally allows visitors to harvest grapes beginning in early August. But this year, it had to delay the start by a week.
The farmer says the greenish grapes taste as delicious as the deep-purple ones, but customers do not value them as much. So the greenish grapes are sent for processing.
This orchard worker is trying to ease the heat impact on grapes by watering them at night and leaving many leaves on the vines to create shadows.
The extreme heat is also having a major impact on Japan’s fisheries industry.
This aquafarm in Kagoshima Prefecture is cultivating a fish called kanpachi, or greater amberjack, of which Kagoshima is a major producer.
According to a local fisheries cooperative, the overall water temperature has risen due to factors including the extreme heat. As a result, the fish eat only 50 percent to 80 percent of what they usually would, and don’t grow as much. The best water temperature for raising the fish is said to be around 28 degrees Celsius, but it has been over 30 degrees for many days since mid-August.
It usually should take about an hour to feed the fish in an outdoor tank, but this year, the fish have stopped eating after just 30 minutes.
The fisheries cooperative says that if sea temperatures continue to rise above 30 degrees Celsius, it will be difficult for the fish to grow. Some may even suffer from having their meat turn white due to the heat, damaging its quality.
Shinohara Shigeto, head of the Tarumizu City fisheries cooperative, said he prays the water temperatures will drop next year. But he added that measures will have to be taken based on the assumption that sea temperatures will rise to 32 degrees, and to encourage the fish to grow before temperatures hit 30.
Heatstroke has increased
According to the Fire and Disaster Management Agency, 83,238 people across the country were taken to hospitals for heatstroke from April 29 to August 25 – an increase of more than 5,200 compared to the same period last year.
Of these, 108 died and 28,682 had severe or moderate symptoms that required hospitalization.
Why’s it so hot?
A research team that included the Japan Meteorological Agency analyzed this year’s record heat and concluded that global warming may have had an impact.
In an analysis method called “Event Attribution,” it is possible to compare a hypothetical Earth, where global warming has not progressed, and the real Earth, where global warming has advanced, in simulations. It also can show how much global warming has affected individual events such as extreme heat and heavy rain.
When this sort of analysis was applied to July’s extreme heat, a designation of a “once in 10 years event” was appropriate if the impact of global warming was considered. However, when the model with no impact from global warming was used, the simulations showed that intense heat would almost never occur.
A different hazard of Japanese summers is typhoons.
In recent years, research has shown that typhoons are moving more slowly ― including the recent Typhoon Shanshan, which crawled across the nation for close to a week. This increases the chance of damage from heavy rain.
University of Tokyo Professor Nakamura Hisashi said that if sea surface temperatures continue to rise, more typhoons could stay strong. He warned that vigilance is still needed this year since the typhoon season has yet to end.
