Unprecedented Heavy Rains in Japan and Climate Change Impacts in the Summer of 2013

Warnings of “unprecedented heavy rain,” were issued by the Japanese Meteorological Agency (JMA) for Fukui, Kyoto and Shiga, using a new warning system. The 18th typhoon of 2013 covered two thirds of Japan and unleashed torrential rain and strong winds which included Fukushima Prefecture, where radioactive water was discharged to prevent the damaged Fukishima nuclear complex from flooding.

According to local police tallies, Typhoon Man-yi had left at least three people dead and four missing and presumed dead while 70 people sustained injuries from the bad weather and nearly 1,500 houses were flooded. Almost half a million (498,000) Japanese residents were evacuated with some 268,000 residents ordered to leave in Kyoto alone. In Osaka, about 290,000 residents in the city’s harbor area were forced to flee.

In 48 hours there was about 300 mm of rain in Kyoto and Otsu which is more than they usually get for the entire month. Precipitation exceeded 500 mm in parts of Mie and Nara. Transportation was impacted across the country including trains, expressways and air travel.

According to a report from the Japanese Meteorological Agency, the nation experienced a number of extreme weather events in the summer of 2013 including heavy precipitation. In places like the Tohoku region, July was 182 percent above average and Hokuriku region was 151 percent above average. Areas in Yamaguchi, Shimane, Akita and Iwate Prefectures were also hit by unprecedented heavy rains.

In the summer of 2013 Japan had highest average temperature ever recorded and the country registered a new national record maximum temperature of 41.0°C in Ekawasaki in Shimanto City, Kochi Prefecture. A total of 143 observation stations broke or tied their daily high temperature records.

The JMA report concludes that temperatures will continue to increase and attributes these increases to increases in atmospheric CO2:

"It is virtually certain that the summer (June-July-August) mean surface temperature over Japan has risen in the period from 1898 onward and the annual number of days with a maximum temperature of 35°C or above in the country has increased in the period from 1931 onward, analyzing observational records at stations considered to have been affected to a lesser extent by local urbanization. These long-term trends can be attributed in large part to global warming caused by increased concentrations of greenhouse gases such as CO2."