The aim of this report is to promote research and development on climate modelling for near-future ranging from weeks to decades and their use in society.

It is an urgent task for Japan and even other countries to build an adaptive and resilient society that can cope with the risks of natural disasters and climate change appropriately. For that purpose, further improvements in predictions of weather and climate on a variety of temporal and spatial scales, and their use to assess the impact on human society and the natural environment is required. It is also necessary to deliver such information to stakeholders in a form that is easy to use, and to effectively convert it into countermeasure planning, decision making, and behavioral change. This is mainly done through weather forecasting and climate change prediction for the next 50 to 100 years. However, in recent years, there has been a growing demand for natural disaster response that considers climate change risks together. Local governments are increasingly aware of the need to predict weeks, months, years, or even decades ahead to plan and take measures for climate change mitigation/adaptation and disaster prevention/mitigation (Figure ES-1). The need for a similar time scale is seen in the industrial sector as well. Private companies are required to understand and disclose the financial impact of climate-related risks in response to the recommendations of the Task Force on Climate-related Financial Disclosure (TCFD).

Under these circumstances, the R&Ds of climate modelling for scales ranging from weeks to decades and assessment of the impacts of natural disaster and climate change on natural environment and human society has become more active in recent years. To accelerate these movements and connect the R&D and social applications, effective and systematic governmental supports are required. Therefore, this report proposes the R&D strategy aiming at the advancement of "prediction" (i.e., climate modelling) and "impact assessment" for time scales ranging from weeks to decades, and the promotion of their social utilization.

The R&D agenda consists of three pillars: "prediction," "impact assessment," and "data and analysis infrastructure" (Figure ES-2). The followings are some of the measures that should be taken to address these R&D issues. Common to all these measures is the importance of building a certain system or network and making efforts that transcend existing fields and sectors.

• (1) Strengthening cooperation between "prediction" and "impact assessment"
• (2) Establishment of a cross-disciplinary research environment
• (3) Concurrent promotion of multi research programs and projects
• (4) Strengthening collaboration between research and operations
• (5) Coevolution of R&D with data and analysis infrastructure
• (6) Strengthening collaboration with the fields of mathematical science and information science and technology
• (7) Encourage young researchers

Building a cross-disciplinary and mission-oriented network of scientists would be desirable to make predictions over a wide range of time scales. Collaboration with scientists and practitioners in the fields of "impact assessment" and social application is also essential to effectively connect the R&D of "prediction" and social applications. Individual relevant research programs and projects should be interlinked with each other. The Center for Climate System Research (CCSR) at the University of Tokyo established in 1991 has raised the level of Japan's R&D in climate change prediction to that of leading countries in this field. It would be useful to learn from these past experiences.

Reducing the risk of climate change and natural disasters is an urgent social and environmental issue. Since all citizens are involved it, collaboration with multi-stakeholders across the process of R&D, from its planning and social application. Planned R&D from a medium- to long-term perspectives is required as well as producing short-term results. When these can be promoted in a well-balanced manner, R&D of prediction on a scale of weeks to decades, which is the target of this proposal, can be effectively promoted.