A primary response to concerns about climate change has been international action to address the issue, particularly through the UNFCCC. International action to date has focused mainly on mitigation, although adaptation is mentioned in UNFCCC Article 4.1 (e) and in funding by the Global Environment Facility (GEF) of adaptation studies (e.g., the Caribbean Planning for Adaptation to Climate Change program). Multinational action is required because no single country or small group of countries can reduce emissions sufficiently to stop GHG concentrations from continuing to grow and because wherever emissions originate, they affect climate globally. Because the extent and urgency of action required to mitigate emissions depends on our vulnerability, a key question is the degree to which human society and the natural environment are vulnerable to the potential effects of climate change.

At the first meeting of the Conference of Parties to the UNFCCC in 1995, governments reviewed the adequacy of existing international commitments to achieve this goal and decided that additional commitments were required. They established the Ad Hoc Group on the Berlin Mandate (AGBM, 1995) to identify appropriate actions for the period beyond 2000, including strengthening of commitments through adoption of a protocol or another legal instrument. The AGBM process culminated in adoption of the Kyoto Protocol in December 1997 (United Nations, 1997). In the Kyoto Protocol, industrialized countries (Annex I Parties to the UNFCCC) agreed to reduce their overall emissions of six GHGs by an average of 5% below 1990 levels between 2008 and 2012. The Protocol also allowed the Parties to account for the removal of GHGs by sinks resulting from direct, human-induced land-use change and forestry activities, emissions trading, “joint implementation” (JI) between developed countries, and a “clean development mechanism” (CDM) to encourage joint emissions reduction projects between developed and developing countries and a commitment to provide assistance in meeting the costs of adaptation for countries deemed most vulnerable to the adverse effects of climate change using the proceeds of the CDM (Article 12). To date, the Kyoto Protocol has not entered into force. The UNFCCC also established national reporting requirements for all Parties regarding their emissions and their potential vulnerabilities/adaptation options. These reporting obligations are being fulfilled through preparation of National Communications to the UNFCCC.

The foundation for any policy to address the climate change problem is information on GHG emissions, the climate system and how it may change, likely impacts on human activities and the environment, and the costs and co-benefits (e.g., protecting primary forests not only retains stored carbon in the trees but also confers the “co-benefit” of biodiversity protection; Kremen et al., 2000) of taking steps to reduce GHG emissions or to change land use. To provide the best available scientific information for policymakers and the public, governments established the IPCC to periodically assess and summarize the state of knowledge in the literature related to climate change. The IPCC completed comprehensive assessments in 1990 and 1995 of the effects of human activities on the climate system, potential consequences of climate for natural and human systems, and the effectiveness and costs of response options (IPCC, 1990, 1996a,b,c). In addition, the IPCC has prepared numerous special reports, technical papers, and methodologies on topics ranging from radiative forcing of climate to technologies, policies, and measures for emissions mitigation. As knowledge has progressed, IPCC assessments have added a regional focus by assessing regional climate modeling and regional sensitivities and adaptive capacity.

Other international bodies also are taking up the challenge of climate change. These organizations include the World Bank, the United Nations Environment Programme (UNEP), the UN Development Programme (UNDP), and the GEF, as well as a variety of regional institutions. Although a primary audience for this report is those who are involved in negotiating and implementing the UNFCCC and, to some extent, other international agreements on global environmental problems, the report also contains information that is useful to other international institutions. The report has been designed to be useful in assessing potential projects and opportunities for investment that will be robust to potential negative effects and to emerging opportunities from climate change.

Governments have initiated a spectrum of responses, ranging from international assessments of climate science, impacts, and abatement strategies (the United States, for example) to implementation of a legally binding mitigation policy (Sweden, for example, has implemented a domestic carbon tax on direct fuel use and on fuel use in the transportation sector; see also OECD, 1999). Governments also have produced country studies, vulnerability assessments of sea-level rise, and national communications; carried out GHG reductions in other countries; and created research opportunities and fora for exchanges of ideas and data. Such management of climate-related research and educational activities has accelerated in the wake of climatic assessment that suggested a discernible human influence on climate (IPCC, 1996a). Similarly, many countries have implemented policies for reasons unrelated to climate change that nevertheless have led to reductions of GHG emissions (e.g., the ethanol program in Brazil, support to renewable energy and energy efficiency in a large number of countries). With regard to adaptation, the first National Communications to UNFCCC from most countries contained analyses of vulnerability and adaptation options.

At the local level, dozens of cities—mainly in industrialized countries—have adopted GHG emission reduction targets and have taken measures to implement them, mostly in the energy and transport sector. In many cases, these policies have been defined by coupling climate protection objectives with other, more local objectives: co-benefits such as reducing air pollution, traffic congestion, or waste production. Some measures, such as water conservation, are adaptive (more resilient to drought) and reduce emissions (less energy for pumping). The use of “social” policy instruments such as public awareness campaigns, information, and technical assistance is commonplace (OECD, 1999). With regard to adaptation, for example, the Federation of Canadian Municipalities is promoting adaptation as well as mitigation measures.

Many countries have developed national climate strategies that are based on a diverse range of policy instruments such as economic instruments, regulation, research and development, and public awareness and information. Energy efficiency, fuel switching, public transportation, and renewable energies typically are promoted. The government sector itself is an increasingly common target for GHG mitigation, and “greening” of government purchasing policies has started to take place in some countries (OECD, 1999).

Overall, these policies and measures to date have had limited effect on emissions, probably because of their lack of integration in a truly global, long-term framework, as well as continued economic growth around the world (AGBM, 1995).

Numerous private businesses have developed plans to facilitate trading of permits for carbon emissions or have set up schemes to help manage CDM transactions if the Kyoto Protocol is ratified or some other instrument of carbon policy is put in place by some nations. Moreover, large multinational corporations such as Shell International and BP Amoco have declared that they will voluntarily observe elements of the Kyoto Protocol (van der Veer, 1999; Browne, 2000). International scientific organizations have responded to the prospect of climate changes for more than 2 decades, from the second objective of the Global Atmospheric Research Program (GARP) to a series of World Climate Conferences sponsored by the World Meteorological Organization and UNEP. The International Council of Scientific Unions and dozens of national scientific societies have responded by creating journals to publish the results of climatic assessments, organizing many meetings and symposia to further our understanding of climate-related scientific issues, and creating committees to help steer research in promising directions.

Similarly, environmental nongovernmental organizations (NGOs) around the world have initiated climate campaigns with the aim of convincing citizens and governments to strengthen the Kyoto Protocol. Meanwhile, direct advertisements have appeared in the media—primarily sponsored by organizations that are attempting to influence public opinion to oppose the Kyoto Protocol.

Natural and human systems have adapted to spatial differences in climate. There also are examples of adaptation (with varying degrees of success) to temporal variations—notably, deviations from annual average conditions. Many social and economic systems—including agriculture, forestry, settlements, industry, transportation, human health, and water resource management—have evolved to accommodate some deviations from “normal” conditions, but rarely the extremes.

Adaptations come in a huge variety of forms. Autonomous adaptations invariably take place in reactive response (after initial impacts are manifest) to climatic stimuli as a matter of course, without directed intervention by a public agency. The extent to which society can rely on autonomous, private, or market adaptation to reduce the costs of climate change impacts to an acceptable or nondangerous level is an issue of great interest. There is little evidence to date that efficient and effective adaptations to climate change risks will be undertaken autonomously (see Chapter 18).

Planned adaptations can be reactive or anticipatory (undertaken before impacts are apparent). Potential adaptations include sharing losses, modifying threats, preventing or decreasing effects, changing use, and changing location. There are many lists of adaptation measures, initiatives, or strategies that have potential to moderate impacts, if they were implemented. Such lists indicate the range of strategies and measures that represent possible adaptations to climate change risks in particular sectors and regions. Only in a few cases have such lists of potential adaptations considered who might undertake them, under what conditions might they be implemented, and how effective might they be.

Knowledge of processes by which individuals or communities actually adapt to changes in conditions over time comes largely from analog and other empirical analyses. These studies indicate that autonomous adaptations tend to be incremental and ad hoc, take multiple forms, occur in response to multiple stimuli (usually involving a particular catalyst, rarely climate alone), and are constrained by economic, social, technological, institutional, and political conditions

Although an impressive variety of adaptation initiatives have been undertaken across sectors and regions, responses are not universally or equally available. Adaptation options generally occur in socioeconomic sectors and systems in which turnover of capital investment and operating costs is shorter, and less often where long-term investment is required. Examples include purchase of more efficient irrigation equipment by individual farmers in anticipation of increased evapotranspiration in a warmer climate, design of bridges or dams to account for an expected increase in sea level or extremes of drought and flood, purchase of insurance, abandonment of insurance coverage to people living in high-risk areas such as coastlines, and creation of migration corridors for species expected to be forced to migrate with climate change.

Often more than one adaptation option is available. People rarely seem to choose the best responses—those among available options that would most effectively reduce losses—often because of an established preference for, or aversion to, certain options. In some cases, there is limited knowledge of risks or alternative adaptation strategies. In other cases, adoption of adaptive measures is constrained by other priorities, limited resources, or economic or institutional barriers. Recurrent vulnerabilities, in many cases with increasing damages, illustrate less than perfect adaptation of systems to climatic variations and risks. Chapter 18 describes some evidence that the costs of adaptations to climate conditions are growing.

Current adaptation strategies with clear applications to climate change in agriculture include moisture-conserving practices, hybrid selection, and crop substitution. In the water resources sector, current management practices often represent useful adaptive strategies for climate change. Some analysts go further to point out that certain adaptations to climate change not only address current hazards but may be additionally beneficial for other reasons. Such evaluations are further complicated by the existence of secondary impacts, related to the adaptation itself. For example, water development projects (adaptations to water supply risks) can have significant effects on local transmission of parasitic diseases. Improved water supply in some rural areas of Asia has resulted in a dramatic increase in Aedes mosquito breeding sites and, consequently, outbreaks of dengue (Section 18.4.4).

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