Typhoons striking or approaching Japan from the Pacific side of the archipelago have increased by 20 percent over the past 40 years, notably in the Kanto, Tokai, Kinki and Shikoku regions, researchers found.
Tokyo, in particular, has weathered a 50-percent increase in typhoons since 1980, according to data released Aug. 25 by the Meteorological Research Institute.
Researchers believe that a high-pressure system develops more often than before in the north and west over the Pacific Ocean, drawing typhoons to these islands.
The scientists compared the number of typhoons that approached Japan in the last 20 years with the figure for 20 years previously.
They found that the number of typhoons that approach many areas of Japan except Kyushu and those on the Sea of Japan coast has markedly increased.
At most observation points, the number of typhoons that hit in the last 20 years rose by 20 percent or more than in the previous 20 years.
In Kyushu, Okinawa Prefecture and other areas on the Sea of Japan side, the difference was not significant, researchers said.
Typhoons, which move along the edge of a high-pressure system, used to pass through the Pacific Ocean south of the Japanese islands.
But during the past 40 years, a high-pressure system has developed annually from summer over the Pacific Ocean that on average stretches about 500 kilometers to the west and 300 km to the north.
The change has drastically affected the course of typhoons, with the result that they more often get closer to land.
During the past 40 years, the power of typhoons has intensified but they move slower, the researchers said.
They said the change was most likely related to global warming and were unsure if the trend will continue.