2011 was in retrospect, a historic year of major disasters such as the earthquake and tsunami in March, the heavy rainfalls and mudslides in the Kii Peninsula caused by Typhoon No. 12 in September, and the floods in Thailand in October. The reconstruction of new communities is underway in areas damaged by the Great East Japan Earthquake. On the other hand, from a long-term point of view, it is unlikely that various areas in Japan can avoid natural disasters such as earthquakes, tsunami, typhoons, heavy rains and high tides even in the future. In addition, climate change, energy and resource problems, ageing population, etc. are predicted to become even more prominent. In other words, a big issue in this century will be how to respond to these risks, and the complex risks that arise from a multiplication of these risks. Well, in order to construct a sustainable society, what should we learn about risk management based on the experience of 2011?

One of the lessons we should learn from the March 11 earthquake and nuclear accident is that it is extremely important to take predictive measures against risks. From past, people have been saying “providing is preventing,” but I want to focus on a new idea that has appeared about this “providing.” In September last year, the Central Disaster Prevention Council published a report in which two stages of response to disasters were given. Disaster reduction (protection of human lives through evacuation and rescue) will be the response for a tsunami of maximum scale, and disaster prevention will be the response for a once-in-a-hundred-year tsunami which a person may possibly experience in his or her life. Furthermore, at the end of the year on December 27, the Basic Disaster Prevention Plan was revised based on this. Nature surrounding us can be extremely violent and at times exert a force that surpasses the protective equipment made by humans. Warding off these external forces and suppressing human casualties to a minimum through evacuation in such cases is the idea of disaster reduction.

On the other hand, as human lives and economic damage will occur frequently without any protection, under a certain amount of external force (design tsunami), several protective facilities will have to be combined to protect human lives, property, economic activities, etc. What is important in this idea is that the largest-scale tsunami should be assumed as a premise for preventive measures in tsunami disaster prevention. I urged the authorities to clearly include this in the disaster prevention policy, and to take measures to reduce damage to the minimum even for a tsunami that cannot be prevented. From past, it has been said that the strength of nature surpasses human efforts, and the importance of disaster reduction was also a lesson from the 1995 Great Hanshin Earthquake, yet it cannot be denied that this awareness has not permeated across the whole society. For potentially major risks to the safety of the society such as a major disaster or nuclear accident, it is necessary to once again recognize the importance of this idea and be specific about risk measures.

Predictive measures are also important in evacuation during emergencies. What is important in order to avoid huge damage is information transmission and when a tsunami occurs, the challenge is how to transmit the information accurately to the residents. Currently, the main information transmission methods during a tsunami are the tsunami warnings and advisories from the Japan Meteorological Agency, and the way they are being released is being improved. Together with such warnings based on predictions, I think it is also necessary to provide real-time information through monitoring. If tsunami information observed at the coast is transmitted to personnel in self-governing organizations near the coast, residents and tourists, I am sure it will be a strong motivation for early evacuation. If all the coasts of Japan were included in this observation network, it is possible to inform residents of an on-coming tsunami approximately 10 to 20 minutes before its arrival. The preparation of ocean bottom seismographs and tsunami observation networks will be included in the budget proposal for the next fiscal year.

Meanwhile, the importance of preventive measures against climate change, a risk on a global scale, is also coming to be recognized internationally. Reports on damage such as increased rainfalls, floods and droughts, mudslides, effects on agriculture, and heat strokes have become annual affair and the effects of climate change are slowly becoming more obvious. In the future, as there will be a sudden increase in people who will be affected due to population increases in developing countries, climate change should be recognized as not just an environmental problem, but a security problem of a global society.

There are two measures against climate change, mitigation measures to reduce carbon dioxide (CO₂), and adaptation measures to provide against the adverse effects. The aim of the mitigation measures is to suppress the reckless advancement of global warming, and stabilize it below the level at which human society can adapt. This can be said to be a measure to avoid the earth environment becoming unmanageable. What should be noted in this unmanageable situation is the consideration for a faraway future that a catastrophic change whereby over a long time, the glaciers of Greenland melts and raises the sea level around the world by as much as seven meters will not be triggered. On the other hand, adaptation measures are predictive measures taken against the adverse effects of global warming because a certain degree of global warming cannot be avoided even when the mitigation measures have been effective. It can therefore, be said to be measures against unavoidable adverse effects. An optimal combination of these two measures will be the desired measure for climate change.

Nevertheless, at the COP17, global warming negotiations, held at Durban at the end of last year, agreement was not reached on the emission reduction framework for major CO₂ emitting countries, including the United States and China. Under the current situation whereby global greenhouse gases continue to increase, we have to expect the advancement of global warming in the next few decades. As a result, the need for mitigation and adaptation measures has increased. The base of predictive measures against climate change is climate prediction. In other words, based on earth observation including satellites, and future predictions based on environment monitoring and climate model, to predict the extent of the possible effects and damage and utilize them to implement measures. On the other hand, as inaccuracies remain in future predictions for the climate, it is necessary to flexibly repeat examinations of measures. Improve climate prediction based on the latest observation and research development, and change the current climate change adaptation measures into something more appropriate. I believe that flexible policy developments based on the link between such science and policy will become more important in the future.

In the column of January 1^st, 2009, Hiroyuki Yoshikawa, former president of The University of Tokyo, wrote the following on how science should be in order to understand and realize sustainability of the earth and society: “Traditional use of science has clarified the nature of existence in the laboratory in as clean environments as possible while magnifying two dimensional spaces with microscopes and three dimensional spaces with telescopes. However, unlike the above, research on sustainability must determine how we should act in reality, not just in the laboratory, and take into account the variations that occur from the past through to the future. To achieve this goal constitutive theory to obtain the proper action guidelines will need to be made using simulations on a supercomputer, which can be regarded as a fourth dimensional lens, while also forecasting possible variations.” (January 1^st, 2009 Opinions “Scientific Sustainability Research”). The predictive measures discussed thus far mean exactly the same as taking proper actions while forecasting variations. Therefore, it is necessary to construct science that will predict and analyze the natural environment and society of the future.

Faced with the March 11 earthquake and nuclear accident, and with climate change becoming more obvious, the importance of ensuring the safety and security of a society has once more become widely recognized as a foundation for a sustainable society. Climate change or natural disasters are not the only risks though, because they are varied and complex and include socio-economic costs as well. In order to ensure the safety and security of a society, it is important to take predictive measures as far as possible, and not respond after a disaster, accident or crisis has happened. There are differences of time, space and risk features between climate change which advances over more than several decades, and natural disasters which create huge damage within a few hours. Therefore, in order to take predictive measures against various risks, it is necessary to develop a wide range of science and technology which will provide proper action guidelines while forecasting risk changes accurately to society. Predictive risk management is an important scientific issue in order to understand and realize sustainability of the earth and society and here it plays a big role in science and technology for solving issues of the 21^st century.

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