There is a growing need to integrate multiple simulations (integrated simulation)?in order to simulate complicated system's behavior. Earth system simulation is a typical example. If we want to simulate total behavior of the earth system, we need to integrate simulations of atmospheric circulation, oceanic circulation, aerosol diffusion, ecological system, traffic system, economic system and so on. Researchers in different fields, such as climatology, oceanography, geochemistry, etc. are developing simulation programs for their own research purposes. To understand and predict the behavior of the earth system, which is a quite complicated system involving all of such fields, it is necessary to integrate the simulation programs developed independently for different purposes. Only limited effort, however, has been so far made to make the integration possible.

From this point of view, this strategic program proposes:
1. Building a community of collaborative researchers who are willing to accept a certain level of restrictions in their simulation programs to make them interoperative, and
2. Developing infrastructure that allows the researchers' community to carry out integrated simulations without imposing an excessive burden on the researchers.

Taking advantage of achievements made through prior investment, freely accessed/ open environment for integration of multiple simulations is recommended to be constructed and research and development should be carried out going ahead of other countries.

In recent years, the problems of global environments get worse, as seen in global warming, environmental pollution, the exhaustion of resources, the reduction of biodiversity, and so forth. Concrete targets for mitigating the climate change have been set in international negotiation. It is urgent to tackle the problems so as to achieve the targets. In addition, it is sufficiently recognized that the creation of a social system adapted for the climate change is urgent. Policy decisions meeting such social needs have huge influences over the future.
In order to make decisions more reasonable and convincing, it is required to properly forecast future and also design countermeasures against the problems. The object of the forecast and the design is an "earth system" in which a variety of elements are interacted mutually. Accordingly, it is strongly required that the policy decisions are technologically supported by simulations. Pieces of knowledge have been accumulated in the disciplines of atmospheric circulation, oceanic circulation, aerosol diffusion, ecological system, traffic system, economic system, and so forth. On the other hand, the system for linking and using the pieces of knowledge is extremely insufficient.

It is difficult for researchers carrying out intellectual exploration to have an incentive for taking care of a technical consistency with other disciplines. That is why it difficult to link and use simulation programs each other. To overcome this difficulty, a new community should be built which has an incentive different from that of individual disciplines. The community will work to construct a system for the integration of multiple simulations. Community building is recommended to be promoted with an issue of "Creating a New Society Adapted for Climate Change". Driven by a strong social wish adapting for climate change, the government and the researchers collaborate to overcome this difficult issue.

The community should be formed by researchers interested in the integrated simulation from the academic disciplines such as climatology, oceanography, geochemistry, bionomics, social psychology, traffic engineering, economics, and so on in which their own simulation programs have been constructed for their own researches, and from the academic disciplines such as statistical mathematics, computer science, and so on which can provide scientific knowledge required to execute the integrated simulation. In the community, the whole image of a required simulation and technological specifications necessary for integrated simulations should be investigated, defined, and agreed.

A technological platform on which the integrated simulations are executable should be constructed based on the agreed technological specifications. On the technological platform, a number of simulation programs and databases will be connected via an information network, and a control program will be implemented. In addition, statistical mathematics technologies for optimizing a large-scale simulation program will be developed through a number of integrated simulations. The community members will build their own simulation programs and databases on the technological infrastructure, and will try to get new perspectives through the collaborations. Accordingly, the technological infrastructure should be continuously developed through the trial and error.

To continuously develop the technological infrastructure, a project head office, the core of the newly formed community, is recommended to be set up in a public research organization1. A program officer as a president for this project and a fund manager as a responsible person for fund-raising should be deployed in the head office. They will captain the project teams and provide research-fund. Engineers staffed in the project head office should support the construction and maintenance of a research infrastructure through close cooperation with the researchers from home and abroad.
Continuous fund-raising, dialogues and cooperation with the researches from home and abroad are necessary for the research and development of fundamental infrastructures. In the past, such efforts were made by researchers themselves. Reflecting on the facts, financially and technologically supported research environment should be provided to researchers under the leadership of program officer and fund manager. It makes the research project attractive and continuous.

As the technological platform is aiming at the platform for mutual connections, it should be common. The related technological trends of other countries should be studied, and the collaboration should be made appropriately. The project promotes that the technological platform becomes widely used and is recognized as a world standard. Japan should provide technological leaderships to solve the large-scale, complicated global problems. Researchers from abroad (including developing countries having no large-scale computational resources) are welcome to construct shared technological infrastructures.

It is very beneficial for the society that the results of research are opened for public and are accountable. The head office should ensure accountability for the results without imposing an excessive burden on individual researchers. Under the system, open mind-set of the researchers will be encouraged.