Advisers to the Nation on Science, Engineering, and Medicine

The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. Upon the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters. Dr. Ralph J. Cicerone is president of the National Academy of Sciences.

The National Academy of Engineering was established in 1964, under the charter of the National Academy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achievements of engineers. Dr. Charles M. Vest is president of the National Academy of Engineering.

The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, upon its own initiative, to identify issues of medical care, research, and education. Dr. Harvey V. Fineberg is president of the Institute of Medicine.

The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy’s purposes of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Academy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Ralph J. Cicerone and Dr. Charles M. Vest are chair and vice chair, respectively, of the National Research Council.

www.national-academies.org

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The implications of climate change for the environment and society depend not only on the rate and magnitude of climate change, but also on changes in technology, economics, lifestyles, and policy that will affect the capacity both for limiting and adapting to climate change. The workshop that is the subject of this report was organized by the National Research Council’s (NRC’s) Committee on the Human Dimensions of Global Change and the Climate Research Committee to initiate a dialogue among interested researchers to explore the requirements for descriptions of socioeconomic and environmental futures to complement climate scenarios. Participants came from several countries and considered approaches and methodological issues in developing socioeconomic scenarios, the forces and uncertainties that will affect adaptation potential and vulnerability as well as emissions and mitigation potential, and the possible elements of a research plan to advance development of socioeconomic scenarios and narratives.

The objectives of the workshop were to review the state of science for considering socioeconomic changes over long time frames; clarify definitions and concepts to facilitate communication across research communities; brainstorm about driving forces and key uncertainties that will affect impacts, adaptation, and vulnerability and mitigation in the future; and consider research needs and the elements of a strategy for describing socioeconomic and environmental futures for climate change research and assessment. Specifically, the participants reviewed narrative and quantitative methods from a range of disciplines for developing long-term

scenarios of socioeconomic futures; identified key factors that might influence adaptation, mitigation, and the environment in the coming decades and that need to be covered in future scenarios; discussed a new process for scenario development that uses representative concentration pathways (RCPs) of future forcing and examined the range of socioeconomic assumptions in model runs consistent with the RCPs; and shared prior experience in the use of narratives and scenarios.

The workshop addressed a number of specific methodological challenges and opportunities. First, any assessment of options to prepare for a changing climate requires not only current data on socioeconomic, climate, and other natural conditions, but also projections that extend for decades (centuries for some types of effects, such as sea level rise). Projections on these time scales challenge conventional scientific methods, and thus it is important to develop and apply socioeconomic scenarios consistent with their proper uses and limits, including a clear understanding that scenarios are not predictions but rather sets of internally consistent assumptions for testing the robustness of potential strategies to a range of potential futures.

Second, for assessments that seek to compare and synthesize information across different locations or systems, there is an additional need to provide an internally consistent set of data for diverse scenario elements—socioeconomic conditions, emissions, climate, broader environmental circumstances, and resources for responses. In previous assessments, both in the United States and internationally (e.g., the assessments of the Intergovernmental Panel on Climate Change [IPCC] or the Millennium Ecosystem Assessment), developing, disseminating, and applying consistent baselines and scenarios across scales from global to local have posed substantial challenges.

Another challenge in developing scenarios for an assessment is doing so in a way that blends scientific knowledge and input from users so that the scenarios are relevant to their concerns and will illuminate the consequences of different choices under their control in the context of broader uncertainties. Scenarios need to provide just the right amount of guidance and core information to facilitate coordination without overspecifying conditions or providing information that is irrelevant, lacks support from key stakeholders, or is not embedded in relevant institutional context. Again, past assessments have not been as successful as they might be on this score.

Over time, a variety of techniques to develop scenarios have been used, including temporal and spatial analogues and model-based scenarios. Traditional modeling approaches start from initial conditions and project forward, whereas other approaches identify desired future conditions and develop pathways for arriving at them. There have been

advances in the methods available for providing climate information at finer scales of resolution (e.g., statistical and dynamical downscaling methods), but less attention has been given to preparing quantitative and narrative socioeconomic information. Advances in computing capacity are making development of probabilistic scenarios a reality. Recently, the research community developed a new “parallel approach” for developing integrated sets of socioeconomic, climate, and environmental scenarios, which has at least two potentially useful attributes: (1) the introduction of climate scenarios focused on approximately the next three decades, and (2) more flexibility to create socioeconomic scenarios that are embedded in consistent global narratives but that focus on the needs of specific decision makers and locations.

These new techniques and developments provide many options, but it remains to be seen how they can best be used, given inherent challenges. Central motives for holding this workshop were to explore the current state of science in scenario development and application and to discuss opportunities for a next round of assessments, including those of the IPCC and the U.S. Global Change Research Program. The workshop succeeded in raising and exploring these issues and in suggesting new lines of research needed to prepare for development of new socioeconomic scenarios to support future integrated assessments. Consistent with its charge, the panel did not attempt to come to consensus on recommendations or a specific research agenda.

Participants in the workshop identified a number of research needs and opportunities that are described in the report. One particularly important issue is additional research on socioeconomic scenarios for local and regional vulnerability assessments with different degrees of coupling to the global context of the RCPs. Developing such geographically “nested” scenarios will require a better understanding of the nature of interdependence between global trends and local adaptation and mitigation potential. Institutionally, additional coordination and information exchange, integration of data systems, and support for users are needed to realize the potential for increased collaboration that the new RCP scenario process presents. A wider range of insights will be developed if researchers and users from developing countries are integrated into the process to explore interactions among development strategies, adaptation, and mitigation.

The workshop was intended not only to identify research needs and opportunities, but also to support the process of planning the next and fifth assessment report of the Intergovernmental Panel on Climate Change. I wish to thank several leaders of IPCC, Kris Ebi, Ottmar Edenhofer, Chris Field, and Patrick Matschoss, and additional IPCC participants for their engagement. I thank the members of the Panel on Socioeconomic Scenar-

ios for Climate Change Assessments, Kris Ebi, Kathy Hibbard, Anthony Janetos, Mikiko Kainuma, Ritu Mathur, Nebojsa Nakičenovič, and Thomas Wilbanks, who developed the structure for the workshop and selected the participants. Presenters and participants endured “snowmaggedon” in Washington during early February 2010 and contributed their insights and knowledge to a lively and productive discussion. Finally, special thanks are due to Paul Stern, director of the Committee on Human Dimensions of Global Change, and Linda DePugh, of NRC, for their tireless efforts to organize the workshop.

This report has been reviewed in draft form by individuals chosen for their diverse perspectives and technical expertise, in accordance with procedures approved by the Report Review Committee of the NRC. The purpose of this independent review is to provide candid and critical comments that will assist the institution in making its published report as sound as possible and to ensure that the report meets institutional standards for objectivity, evidence, and responsiveness to the study charge. The review comments and draft manuscript remain confidential to protect the integrity of the deliberative process. We wish to thank the following individuals for their review of this report: Karen Fisher-Vanden, Department of Agricultural Economics and Rural Society, Pennsylvania State University; Tom Kram, Global Sustainability and Climate Unit, Netherlands Environmental Assessment Agency; and Brian C. O’Neill, Climate and Global Dynamics Division and Integrated Science Program, National Center for Atmospheric Research (NCAR), Boulder, CO.

Although the reviewers listed above have provided many constructive comments and suggestions, they were not asked to endorse the conclusions or recommendations nor did they see the final draft of the report before its release. The review of this report was overseen by Edward Parson, School of Law, University of Michigan. Appointed by the NRC, he was responsible for making certain that an independent examination of this report was carried out in accordance with institutional procedures and that all review comments were carefully considered. Responsibility for the final content of this report rests entirely with the authoring committee and the institution. Nonetheless, we thank the reviewers and the review coordinator for their diligent analysis and scrupulous comments, which have significantly improved the quality of the report.

Richard H. Moss, Chair

Panel on Socioeconomic Scenarios for Climate Change Research and Assessment