The Challenges... | A Reseponse |
For over a decade nations have worked to formulate domestic policies and international agreements in response to the threat of global climate change. Much has been learned over this period, but two aspects stand out. First, we have begun to confront the sheer complexity of global climate as a policy issue : it would be hard to design a greater challenge to scientific research, public understanding, and reasoned political action. Second, the implications of its peculiarly long-term nature are becoming more evident. There is no short-term solution or targeted policy that can deal with the issue. Climate change is a century-scale threat requiring a century-long analysis effort and policy attention, plus the design of institutions that can sustain a response over generations.
Obvious difficulties are imposed on the policy process by our inadequate knowledge and incomplete observation of the climate system, our uncertainty regarding the influence of anthropogenic greenhouse emissions, and our limited knowledge of the effects of climate change on natural ecosystems. Also increasingly evident are the problems created by the complexities and uncertainties of potential efforts to control human influence on the atmosphere. For example, measures to limit emissions are intertwined with major segments of both the modern industrial economy and more traditional agriculture and forestry. Climate policy cannot be separated from issues of tax structure, international trade regimes, agricultural policy, energy security and conservation initiatives, and other environmental concerns such as urban air pollution and the appropriate role of nuclear power. Moreover, any long-term emissions control agreement inevitably raises questions of international equity, most importantly between the current industrial economies and developing nations.
This tangle of environmental threats, uncertainties, and intersecting policy concerns poses not only a political and economic challenge but also an intellectual one. Means need to be provided to develop and communicate an understanding of the climate issue in all its parts. It is all too easy for policy studies to move into their own orbit, disconnected from the natural science that motivates concern in the first place. Or for scientific research to proceed down its own path, with insufficient concern for distilling those discoveries that are crucial for policy discussion.
Integrating these diverse components of the issue is not an easy task and, like climate policy itself, the needed research and policy guidance is not a one-time task. Knowledge of fundamental climate processes and of detection and attribution of change is continuously evolving. It is not sufficient to assess this knowledge once for policy purposes, or even every four or five years. Effective long-term climate action will only emerge from a sequence of decisions over decades. Thus the process will need to be informed by a continuing flow of policy research and analysis as the science advances and economic and political conditions change, and as we experience the success and failure of agreements along the way.
In these demands, the climate issue is harder than most other environmental problems. Further, given the complicated set of social concerns that intersect at the point of climate discussion, the value of comprehensive, independent sources of analysis is arguably greater than for other issues as well. Indeed, a capacity to provide this type of research and assessment, and sustain it over time in a number of key countries, is itself an important component of needed institutional development.
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With a foundation of a half-century of work on weather and climate at MIT, the CGCS is a shared activity of the School of Science and School of Engineering. It is devoted to research on long-standing scientific problems that impede the ability to make accurate prediction of changes in the global environment. A key CGCS component, with which the Joint Program cooperates closely, is its Climate Modeling Initiative. It is applying fundamental work on climate processes, and global model construction, to studies of the science of climate prediction and its limits. The CEEPR conducts policy research on energy, natural resources, and environmental issues. Created in the 1970s, it is a shared effort of the Sloan School of Management, the Economics Department and the Energy Laboratory.
In addition, the Joint Program collaborates with other groups at the Institute who are working in related areas, such as problems of megacities, mobility, water resources, and international affairs. The Program brings together these experts in the natural and social sciences, energy technology, and political and policy analysis, and applies their talents and more discipline-oriented work to the interdisciplinary challenge of global climate change. Where capacity is lacking at MIT, cooperative efforts have been formed with groups outside the Institute. In particular, a long-term alliance with the Ecosystems Center of the Marine Biological Laboratoryin Woods Hole, Massachusetts, brings to the Program substantial expertise on the impacts of climate change on terrestrial ecosystems.
The Program's efforts are centered around the framework of the MIT Integrated Global System Model (IGSM), which includes an economic model for analysis of greenhouse and aerosol precursor gas emissions and mitigation proposals, a coupled model of atmospheric chemistry and climate, and models of natural ecosystems. All of these models are global but with appropriate levels of regional detail. Since human activity generates a many chemically and radiatively important trace gases, one challenge is to understand the relevant economics in order to predict the magnitude and distribution of these anthropogenic emissions. Predicting natural emissions of trace gases creates another challenge in that they depend on both climate and ecosystem states. Because the analytical models are complex and can require large computer resources, the linking together of the separate components is another source of difficulty.
Given the need for multiple model runs for both policy assessment and uncertainty studies, it is very important to achieve an appropriate trade-off between model detail and computational efficiency. For example, because regional air pollution policies inevitably affect emissions of greenhouse gases, atmospheric chemistry needs to be modeled in some detail. Similarly, appropriate detail is needed to handle feedbacks between climate and atmospheric chemistry, and to predict ecosystem exposure to irritants (e.g., ozone) and nutrients (e.g., nitrate). Unfortunately, the level of attainable detail in any of the models is limited by the corresponding computational demand. For instance, the computer power necessary to adequately resolve the important small-scale eddies in the ocean on a global scale, for multiple integrations over decade-to-century time scales, does not presently exist. Accurate, simplified treatments of these eddies are therefore essential, and a major challenge in the development of a coupled global chemistry/climate model is to distinguish those processes that most need to be included in detail, those which can be omitted, and those which must be included but can be represented in a simplified way.
The MIT IGSM is designed to address both policy issues and some outstanding questions in global change science. For example, how effective would specific policy measures be in alleviating relevant environmental and economic concerns? How costly are they? What are their distributional implications by nation, region, and economic sector? Given the current level of understanding of these phenomena, what are the advantages and risks of waiting for better scientific information and observational evidence before taking stronger policy measures? How will oceanic and terrestrial biospheric uptake of carbon dioxide (CO2), and terrestrial emissions of other greenhouse gases like methane (CH4) and nitrous oxide (N2O), be affected by changing climate? How will climate changes influence the chemistry of the atmosphere and thus the levels of climatically important species like ozone (O3), methane, and aerosols? Do these latter changes constitute a major climate-greenhouse gas or climate-aerosol feedback?
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