Overview of Impacts, Adaptation, and Vulnerability to Climate Change
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1 Overview of Impacts, Adaptation, and Vulnerability to Climate Change STEPHEN SCHNEIDER (USA) AND JOSE SARUKHAN (MEXICO) Lead Authors: J. Adejuwon (Nigeria), C. Azar (Sweden),W. Baethgen (Uruguay), C. Hope (UK), R. Moss (USA), N. Leary (USA), R. Richels (USA), J.-P. van Ypersele (Belgium) Contributing Authors: K. Kuntz-Duriseti (USA), R.N. Jones (Australia) Review Editors: J. Bruce (Canada) and B. Walker (Australia) CONTENTS 1. 1 . Overview of the As s e s s m e n t 77 1. 4 . 4 . Sy n e r gies and Tra d e o ff s 93 1. 4 . 4 . 1 . Sy n e r gies and Tra d e o f fs between 1. 2 . What is Potentially at Stake? 82 Climate Change and Other 1. 2 . 1 . Climatic Change Represents Opportunities Environmental Issues 93 and Risks for Human Development 83 1. 4 . 4 . 2 . Sy n e r gies and Tra d e o f fs between 1. 2 . 1 . 1 . Allow Ecosystems to Ad a p t Adaptation and Mitigation 94 Naturally to Climate Change 84 1. 4 . 5 . Integrated As s e s s m e n t 94 1. 2 . 1 . 2 . Ensure that Food Production is not Th r e a t e n e d 84 1.5. How do Complexities of An a l y s i s 1. 2 . 1 . 3 . Enable Economic Development to Af fect the As s e s s m e n t ? 95 Proceed in a Sustainable Manner 85 1. 5 . 1 . Regional Climate Uncertainties 95 1.2.2. Human-Environment Systems: Implications 1. 5 . 2 . Socioeconomic Uncertainties 95 for Development, Equity, and Sustainability 85 1. 5 . 3 . Risk and Uncertainty 96 1. 5 . 4 . Low-Probability Catastrophic Events 96 1. 3 . How has Society Responded? 87 1. 5 . 5 . Valuation Methods—Monetary Measures 1. 3 . 1 . International Responses 87 or Multiple Numeraires 97 1. 3 . 2 . National and Local 1. 5 . 6 . Damage Aggregation and Distributional Effe c t s 97 Governmental Responses 87 1. 5 . 7 . Discounting 97 1.3.3. Or ganizational Responses 88 1. 5 . 8 . “Safe Emission Levels,” Cost-Effe c t i v e n e s s 1.3.4. Adaptive Responses 88 Analysis, and the Timing of Emission Ab a t e m e n t 98 1. 4 . How are Impacts, Adaptation, and 1. 5 . 9 . Val i d a t i o n 98 Vulnerability Assessed in this Report? 89 1. 4 . 1 . Se n s i t i v i t y , Ad a p t a b i l i t y , and Vul n e r a b i l i t y 89 1.6. How can this Assessment be Used to Ad d re s s 1. 4 . 2 . Detection and At t r i b u t i o n Policy-Relevant Questions? A U s e r s ’G u i d e 99 of Impacts to Climate Change 91 1.6.1. United Nations Framework Convention 1. 4 . 3 . Key Determinants of Impacts 91 on Climate Change 99 1. 4 . 3 . 1 . Magnitude of Change 91 1.6.2. Links to Biodiversity Loss, Desertification, 1. 4 . 3 . 2 . Rate of Change 91 Deforestation and Unsustainable Use of 1. 4 . 3 . 3 . Transient Scenarios 91 Forests, Stratospheric Ozone Depletion, 1. 4 . 3 . 4 . Climate Var i a b i l i t y and Other Global Environmental Issues 99 and Extreme Events 92 1. 6 . 3 . Resource Planners, Managers in National 1. 4 . 3 . 5 . Th r e s h o l d s 92 and Regional Institutions, and Actors in 1. 4 . 3 . 6 . Su r p r i s e s 93 Specialized International Ag e n c i e s 10 0 1. 4 . 3 . 7 . No n l i n e a r , Complex, and Discontinuous Responses 93 Re f e re n c e s 10 0 Overview of Impacts, Adaptation, and Vulnerability to Climate Change 77 1.1. Overview of the Assessment community since publication of the SAR. The evidence is drawn predominantly from published, peer-reviewed scientific The world community faces many risks from climate change. literature. Evidence also is drawn from published, non-peer- C l e a r l y, it is important to understand the nature of those reviewed literature and unpublished sources such as industry risks, where natural and human systems are likely to be most journals; reports of government agencies, research institutions, vulnerable, and what may be achieved by adaptive responses. and other organizations; proceedings of workshops; working To understand better the potential impacts and associated papers; and unpublished data sets. The quality and validity of d a ngers of global climate change, Working Group II of the information from non-peer-reviewed and unpublished sources Intergovernmental Panel on Climate Change (IPCC) offers this have been assessed by authors of this report prior to inclusion Third Assessment Report (TAR) on the state of knowledge of information from these sources in the report. The procedures concerning the sensitivity, adaptability, and vulnerability of for the use of information from non-peer-reviewed and physical, ecological, and social systems to climate change. un p u b lished sources are described in IPCC (1999a) and discussed Building on the Second Assessment Report (SAR), this new in Skodvin (2000). report reexamines key findings of the earlier assessment and emphasizes new information and implications on the basis of Although this report builds on previous assessments, including more recent studies. the SAR and the IPCC’s Special Report on Regional Impacts of Climate Change (IPCC, 1998), the TAR departs from them Human activities—primarily burning of fossil fuels and in important respects. In comparison to previous assessments, changes in land cover—are modifying the concentration of greater attention is given to climate change adaptation; multiple atmospheric constituents or properties of the Earth’s surface pressures on systems; links between climate change, sustainable that absorb or scatter radiant energy. In particular, increases in development, and equity; and characterization of the state-of- the concentrations of greenhouse gases (GHGs) and aerosols the-science and confidence levels associated with key conclusions are strongly implicated as contributors to climatic changes of the assessment (see Box 1-1). This overview chapter does not observed during the 20th century and are expected to contribute attempt to provide a comprehensive summary of the principal to further changes in climate in the 21st century and beyond. findings of the TAR, but it helps to illustrate basic concepts by These changes in atmospheric composition are likely to alter selectively reporting on a few key conclusions, as well as temperatures, precipitation patterns, sea level, extreme events, p r oviding a more comprehensive road map to the materials and other aspects of climate on which the natural environment presented later in the report: and human systems depend. • Part I sets the stage for assessment of impacts, One of several primary issues this report has been organized to a d a ptation, and vulnerability by discussing the context address is a key question before the United Nations Framework of climate change, methods for research on impacts, Convention on Climate Change (UNFCCC): What are the and development of scenarios. These are important potential impacts for societies and ecosystems of different additions to what was emphasized in the SAR. atmospheric concentrations of GHGs and aerosols that absorb Consideration of the context of change (in this chapter) and scatter sunlight (United Nations, 1992)? Answering this draws attention to the relationship of climate change question is a necessary step in assessing what constitutes and sustainable development, including interactions of “ d a ngerous anthropogenic interference in the climate system.” climate variability and change with other environmental This report does not make any judgments about what level of changes and evolving demographic, social, and concentrations is “dangerous” because that is not a question of e c onomic conditions that affect driving forces of science per se but a value judgment about relative risks and change and resources available for adaptation. tradeoffs. The task is to make the evidence about relative risks Assessment of methods (Chapter 2) and approaches as clear as possible. This report therefore describes what is for developing and applying scenarios (Chapter 3) known about the distribution of impacts; how, why, and to cover scientific and technical aspects of research on what extent they differ from region to region or place to place; impacts, providing a review of the science underlying and how this relates to the distribution of vulnerability and the topics covered in other chapters of the report. capacity to adapt. However, it critically assesses the literature • Part II assesses recent advances in experimental work, to help inform policymakers about effects associated with observations, and modeling that contribute to the current d i fferent concentration levels, so they may judge what levels of state of knowledge of baseline trends, vulnerabilities, risk are acceptable. Assessment of what constitutes dangerous and adaptation options in six sectors or resource areas. interference in the climate systems will require analysis of This section of the report integrates material that had the interactions of climate change and social and economic been covered in 18 chapters in the SAR, focusing to a conditions, which are inextricably linked. Understanding the greater extent on cross-sectoral issues. For example, role of socioeconomic factors, particularly adaptive responses Chapter 5, Ecosystems and their Goods and Services, and capacity, is critical. integrates what had been separate chapters on forests, rangelands, deserts, mountain regions, wetlands, Part of the justification for a TAR at this time is the abundance a g r iculture, food security, and other systems; it also of new evidence that has come to the attention of the expert adds assessment of climate change impacts on 78 Overview of Impacts, Adaptation, and Vulnerability to Climate Change wildlife—an issue not covered in the SAR.