Japan Climate Resilience Policy Indicator

• Both the temperature and the number of days with heavy rainfall have increased in Japan. This trend is likely to persist until the end of this century, affecting energy consumption and peak demand.
• Japan is highly exposed to the risk of tropical cyclones, with their frequency and intensity expected to increase over the course of the century. Intense tropical cyclones can pose a significant threat to energy supply reliability, causing disruptions such as those created by typhoons Faxai and Hagibis in 2019.
• With adoption of the Climate Change Adaptation Law in 2018, Japan established a legal foundation for climate change adaptation. It then completed a comprehensive assessment of climate change impacts and established a Climate Change Adaptation Plan. The Strategic Energy Plan (2018) and the Act for Establishing Energy Supply Resilience (June 2020) cover energy sector resilience to natural disasters. However, strategic planning to enhance climate change adaptation and resilience in the energy sector is still at an initial stage, partly because there has not been extensive research on the impact of climate change on energy systems.

Temperature

Japan’s average annual temperature rose 1.24°C per century since 1898. According to the Japan Meteorological Agency, temperature increases were more pronounced in the spring and autumn than in the winter and summer over the last century. The number of hot days (above 35°C) increased in the last century, while the number of extreme cold days decreased. Geographically, the increase in temperature has been more pronounced in urban areas than in rural ones, with Tokyo’s average temperature climbing twice as quickly as that of rural areas.

Compared with the end of the 20th century, annual average temperature is projected to increase by 1.1°C to 4.4°C over the next century, depending on the future level of greenhouse gas concentrations. Both maximum and minimum temperatures are expected to rise, but winter temperatures will likely increase more than summer ones.

With fewer heating degree days (HDDs) and a greater number of cooling degree days (CDDs) in the past two decades, the overall temperature increase has reduced winter heating needs but boosted cooling in the summer. Some studies indicate that summer peak electricity demand may increase as a result of higher cooling needs, except in the northern islands of Hokkaido, where electricity demand is highest in winter. 

Precipitation

Japan’s annual mean precipitation has shown wide-ranging interannual variability, and no clear long-term trend has been identified for annual rainfall levels in the 20th century. However, the number of heavy precipitation days annually increased significantly from 1901 to 2019 and there are fewer days with little or no rainfall.

Although climate projections do not establish a clear trend for annual precipitation, they suggest that heavy and short-term intense rains will become more frequent across the country in 2076-2095 than they were at the end of the 20th century1. The number of dry days per year is also projected to increase steadily.

Tropical cyclones and storms##2##

Regarding extreme weather events, tropical cyclones, also called as typhoons, are Japan’s greatest concern. Although the trend for the number of tropical cyclones is not clear, climate projections suggest that their intensity around Japan may increase in the future. In fact, the INFORM Risk Index gives Japan the highest score for physical exposure to tropical cyclones. Indeed, tropical cyclones have repeatedly caused blackouts in Japan, compromising electricity supply reliability. For instance, Typhoon Faxai damaged the electricity grid in the Tokyo area in September 2019, leaving some 900 000 households without power. Typhoon Hagibis, which struck the same region one month later, again caused power outages for 27 000 homes.

The 2018 Climate Change Adaptation Law established the legal foundation for adaptation measures in Japan, mandating adoption of the Climate Change Adaptation Plan in 2018 (to be renewed every five years) and requiring the development of information systems, reinforcement of regional-level adaptation, and international co‑operation. Regional governments are encouraged to draw up their own adaptation plans and set up local adaptation centres to act as hubs for the collection, analysis and provision of local climate risk data and information on adaptation measures.

To support the implementation of adaptation measures based on the Climate Change Adaptation Law and the Adaptation Plan, the Climate Change Adaptation Information Platform (A-PLAT) provides centralised information related to the impacts of climate change. It aims to help local governments, businesses and individuals develop climate change adaptation measures.

The Climate Change Adaptation Plan introduces seven basic strategies, including incorporating climate change adaptation into relevant policies; developing a scientific research; collecting and analysing climate information; adapting programmes to regional features; improving public awareness; providing aid for climate change adaptation in developing countries; and cross-governmental co‑operation. The Plan estimates the importance of energy sector adaptation as “not high” and the urgency for adaptation as “low”, citing a lack of consensus on the climate impacts on energy systems. Accumulating scientific knowledge on domestic and overseas climate impacts in collaboration with businesses was suggested as an adaptation action.

The 2020 Climate Change Impact Assessment Report, which provides an overview of climate change impacts in seven sectors, assesses the energy sector under the category of “industry and economic affairs”, consistent with the Climate Change Adaptation Plan. The report reaffirms the view of the Climate Change Adaptation Plan, estimating the level of importance as “not high” and the urgency for adaptation as “low” for the energy sector. It states that there is little concrete research on the impacts of climate change on energy systems, even though Japan has witnessed soaring electricity demand during heatwaves and physical damage by strong typhoons.

Nevertheless, even though strategic planning specific to energy sector climate resilience is in its infancy because its importance is hardly recognised, climate-related disasters such as storms and floods have been well managed under natural disaster risk management strategies. As one of the world's most disaster-prone countries, Japan has taken in-depth measures in response to natural disasters, including earthquakes, windstorms and floods, to ensure energy supply stability. The Strategic Energy Plan, which aims for balance among the issues of energy security, economic efficiency and the environment (with safety as the basic premise), recognises the importance of being resilient to natural disasters and supply crises.

Meanwhile, the June 2020 Act for Establishing Energy Supply Resilience goes a step further, stipulating the establishment of a collective action plan for electricity network operators to ensure electricity supply reliability in cases of disaster. While specification to climate resilience is limited, the approach of leveraging policies already in place for responding to natural disasters has been sufficient to manage earthquakes and windstorms. The draft Japan’s 6^th Strategic Energy Plan released on 4 August 2021 also focuses on overcoming the challenges that Japan’s energy system face, including providing stable energy supply against natural disaster.