Photo/Illutration An Asian tiger mosquito (Provided by the Department of Medical Entomology of the National Institute of Infectious Diseases)

One likely consequence of climate change is a growing risk in Japan of mosquito-borne infectious diseases, according to a draft assessment report presented Sept. 9 by an expert panel of the Environment Ministry.

The document also cited a recent succession of disasters triggered by heavy rains, typhoons and other phenomena that it said points to a growing likelihood of global warming having an impact on urban infrastructure.

Such assessment reports are issued every five years after a comprehensive study of literature on the subject.

In this case, 1,400 or so reports and other studies were taken into account, about three times the corresponding figure for the previous study.

The document assessed the impact of climate change in 71 categories in the seven sectors of farming, forestry and fisheries, water environments, ecosystems, disasters, health, the economy and urban life, from the three viewpoints of “significance,” “urgency” and “confidence.” The confidence level was raised in 31 categories.

The “urgency” rating, which reflects the need for new measures, was revised from “medium” to “high” for infectious diseases transmitted by mosquitoes.

The habitat in Japan of the Asian tiger mosquito, which carries the viruses responsible for dengue fever, Zika fever and other diseases, is spreading north as temperatures heat up. The mosquito in 2016 was confirmed to have moved to Aomori Prefecture at the tip of the main island of Honshu.

The draft report mentions the possibility that an alien mosquito species that carries the Japanese encephalitis virus might spread in the future to Kagoshima Prefecture or further north.

“There is a need to strengthen surveillance, so any case of infection can be discovered early, and also to disseminate knowledge on dengue fever diagnosis among medical practitioners,” said Masahiro Hashizume, a professor of environmental epidemiology at the University of Tokyo.

The draft report also includes mention of the fact that weather disasters, including heavy rains of 2018 in western Japan, have led roads to collapse and caused cutoffs of critical services, such as electricity, gas and water supply.

The confidence rating for the impact on urban infrastructure was revised from “low” to “high” as climate change increases the frequency of short-term intense rainfall events and powerful typhoons.

The report will be finalized by the end of this year after receiving input from the public, after which the central government will revise its Climate Change Adaptation Plan in fiscal 2021.

Local governments will also be revising, or working out, similar plans of their own.

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IMPACT OF CLIMATE CHANGE

Key categories in which ‘significance,’ ‘urgency,’ ‘confidence’ are all rated ‘high’

Farm production infrastructure: Water shortage due to smaller snowfalls

Water availability: Drought

Coastal ecosystem in subtropics: Coral bleaching, dead mangroves

Heatstroke: Growth in number of patients transported by ambulance, deaths

Water supply, transportation: Impact on infrastructure, critical services due to growing number of powerful typhoons

(Source: Environment Ministry expert panel’s draft assessment report on impact of climate change)

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