In the past decade, some progress has been made in evaluating potential socioeconomic impacts of climate change and sea-level rise on coastal and marine systems. This progress, however, has not been as substantial as that relating to biogeophysical impacts; nor has it been especially comprehensive (Turner et al., 1995, 1996). To date, emphasis has been in three areas. First, research has focused on the coastal zone itself (we are not aware of any studies of the socioeconomic impact of climate change on open-ocean marine ecosystems). Second, there has been an emphasis on the potential socioeconomic impact of sea-level rise but little on any other climate change variables. Third, emphasis has been on economic effects, not on impacts on social and cultural systems. These emphases are evident in the following review, in which we consider socioeconomic impacts initially as a component of the methodology for vulnerability assessment and then through economic cost-benefit analyses of coastal zones in general and infrastructure developments in particular. In these cases, "benefits" derive from the inclusion of adaptation options—primarily shore protection—into the analyses to derive some net cost. Finally, we consider attempts that have been made to "value" natural systems, as well as the potential social and cultural impacts of climate change.

In the SAR, Bijlsma et al. (1996) reviewed several country case studies that had applied the IPCC Common Methodology for assessing the vulnerability of coastal areas to sea-level rise. These case studies offered important insights into potential impacts and possible responses. Many of the assessments emphasized the severe nature of existing coastal problems such as beach erosion, inundation, and pollution, as well as the effects of climate change acting on coastal systems that already are under stress.

The Common Methodology defined vulnerability as a country's degree of capability to cope with the consequences of climate change and accelerated sea-level rise. The methodology of seven consecutive analytical steps allowed for identification of coastal populations and resources at risk and the costs and feasibility of possible responses to adverse impacts. The SAR also identified the strengths and weaknesses of the Common Methodology. More recently, Klein and Nicholls (1999) have evaluated the IPCC's approach and results, concluding that the Common Methodology has contributed to understanding the consequences of sea-level rise and encouraged long-term thinking about coastal zones. They went on to develop a new conceptual framework for coastal vulnerability assessment that identifies the main components of the natural system and the socioeconomic system, as well as the linkages between them and climate change and other change variables. This framework is outlined in Box 6-5.

In the SAR, data on socioeconomic impacts were derived from country and global vulnerability assessment studies. Figures for several countries were given relating to the population affected, capital value at loss, and adaptation/protection costs (Bijlsma et al., 1996, Table 9-3). For the coastal zone, the authors concluded that:

• There will be negative impacts on several sectors, including tourism, freshwater quality and supply, fisheries and aquaculture, agriculture, human settlements, financial services, and human health.
• The number of people potentially affected by storm-surge flooding is expected to double (or triple) in the next century, ignoring potential adaptation and population growth.
• Protection of low-lying island states and nations with large deltaic areas is likely to be very costly.
• Adaptation to sea-level rise and climate change will involve important tradeoffs, which may include environmental, economic, social, and cultural values.

Since the SAR, there have been several summaries of the socioeconomic results of the vulnerability assessment studies, presenting data at local, regional, and global levels. Examples include case studies of Poland and Estonia (Kont et al., 1997; Zeider, 1997), the Philippines (Perez et al., 1999), Bangladesh (Ali, 1999), Egypt (El-Raey et al., 1999), and The Gambia and Abidjan (Jallow et al., 1999), as well as the regional analyses and global synthesis of Nicholls and Mimura (1998). The initial global vulnerability assessment has been revised on the basis of scenarios for global sea-level rise derived from the Hadley Centre's HadCM2 ensemble simulations and HadCM3 simulations for GHG-only forcing (Nicholls et al., 1999). This assessment indicated that by the 2080s, the potential number of people flooded by storm surge in a typical year will be more than five times higher than today (using a sea-level rise of 0.38 m from 1990 to 2080) and that between 13 million and 88 million people could be affected even if evolving protection is included. Broadly similar results are given in the study undertaken by DETR (1999). However, they note that the flood impacts of sea-level rise are reduced by emissions scenarios that lead to stabilization of CO₂. By the 2080s, the annual number of people flooded is estimated to be 34 million under the 750-ppm scenario and 19 million under the 550-ppm scenario.

Klein and Nicholls (1999) have categorized the potential socioeconomic impacts of sea-level rise as follows

• Direct loss of economic, ecological, cultural, and subsistence values through loss of land, infrastructure, and coastal habitats
• Increased flood risk of people, land, and infrastructure and the aforementioned values
• Other impacts related to changes in water management, salinity, and biological activities.

They also developed a methodology that has not yet been applied in any case studies.

Box 6-5. Conceptual Framework for Coastal Vulnerability Assessment In the scheme illustrated below, analysis of coastal vulnerability starts with a notion of the natural system's susceptibility to the biogeophysical effects of sea-level rise and its capacity to cope with these effects (resilience and resistance). Susceptibility reflects the coastal system's potential to be affected by sea-level rise; resilience and resistance determine the system's robustness or ability to continue functioning in the face of possible disturbance. Together, these factors determine the natural vulnerability of the coastal zone. Resilience and resistance are functions of the natural system's capacity for autonomous adaptation, which represents the coastal system's natural adaptive response. Resilience and resistance often are affected by human activities, which need not only be negative: Planned adaptation can reduce natural vulnerability by enhancing the system's resilience and resistance, thereby adding to the effectiveness of autonomous adaptation. The biogeophysical effects of sea-level rise impose a range of potential socioeconomic impacts. This impact potential is the socioeconomic equivalent of susceptibility; it is dependent on human influences. Socioeconomic vulnerability is determined by the impact potential and society's technical, institutional, economic, and cultural ability to prevent or cope with these impacts. As with the natural system's resilience and resistance, the potential for autonomous adaptation and planned adaptation determines this ability to prevent or cope. Dynamic interaction takes place between natural and socioeconomic systems. Instead of being considered as two independent systems, they are increasingly regarded as developing in a co-evolutionary way, as shown by the feedback loop from the socioeconomic system to the natural system. Sources: Klein and Nicholls (1999); Mimura and Harasawa (2000).

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