IPCC Fourth Assessment Report: Climate Change 2007
Climate Change 2007: Working Group II: Impacts, Adaptation and Vulnerability

6.7 Conclusions: implications for sustainable development

The main conclusions are reported in the Executive Summary and are reviewed here in the context of sustainable development. Coastal ecosystems are dynamic, spatially constrained, and attractive for development. This leads to increasing multiple stresses under current conditions (Section 6.2.2), often resulting in significant degradation and losses, especially to economies highly dependent on coastal resources, such as small islands. Trends in human development along coasts amplify their vulnerability, even if climate does not change. For example, in China 100 million people moved from inland to the coast in the last twenty years (Dang, 2003), providing significant benefits to the national economy, but presenting major challenges for coastal management. This qualitative trend is mirrored in most populated coastal areas and raises the conflict between conservation and development (Green and Penning-Rowsell, 1999). Equally the pattern of development can have tremendous inertia (Klein et al., 2002) and decisions made today may have implications centuries into the future (Box 6.6).

Climate change and sea-level rise increase the challenge of achieving sustainable development in coastal areas, with the most serious impediments in developing countries, in part due to their lower adaptive capacity. It will make achieving the Millennium Development Goals (UN Secretary General, 2006b) more difficult, especially the Goal of Ensuring Environmental Sustainability (reversing loss of environmental resources, and improving lives of slum dwellers, many of whom are coastal). Adapting effectively to climate change and sea-level rise will involve substantial investment, with resources diverted from other productive uses. Even with the large investment possible in developed countries, residual risk remains, as shown by Hurricane Katrina in New Orleans (Box 6.4), requiring a portfolio of responses that addresses human safety across all events (protection, warnings, evacuation, etc.) and also can address multiple goals (e.g., protection of the environment as well as adaptation to climate change) (Evans et al., 2004a; Jonkman et al., 2005). Long-term sea-level rise projections mean that risks will grow for many generations unless there is a substantial and ongoing investment in adaptation (Box 6.6). Hence, sustainability for coastal areas appears to depend upon a combination of adaptation and mitigation (Sections 6.3.2 and 6.6.5).

There will be substantial benefits if plans are developed and implemented in order to address coastal changes due to climate and other factors, such as those processes that also contribute to relative sea-level rise (Rodolfo and Siringan, 2006). This requires increased effort to move from reactive to more proactive responses in coastal management. Strengthening integrated multidisciplinary and participatory approaches will also help improve the prospects for sustaining coastal resources and communities. There is also much to be learnt from experience and retrospective analyses of coastal disasters (McRobie et al., 2005). Technological developments are likely to assist this process, most especially in softer technologies associated with monitoring (Bradbury et al., 2005), predictive modelling and broad-scale assessment (Burgess et al., 2003; Cowell et al., 2003a; Boruff et al., 2005) and assessment of coastal management actions, both present and past (Klein et al., 2001). Traditional practices can be an important component of the coastal management toolkit.

Box 6.6. Long-term sea-level rise impacts (beyond 2100)

The timescales of ocean warming are much longer than those of surface air temperature rise. As a result, sea-level rise due to thermal expansion is expected to continue at a significant rate for centuries, even if climate forcing is stabilised (Meehl et al., 2005; Wigley, 2005). Deglaciation of small land-based glaciers, and possibly the Greenland and the West Antarctic ice sheets, may contribute large additional rises, with irreversible melting of Greenland occurring for a sustained global temperature rise of 1.1 to 3.8°C above today’s global average temperature: this is likely to happen by 2100 under the A1B scenario, for instance (Meehl et al., 2007). More than 10 m of sea-level rise is possible, albeit over very long time spans (centuries or longer), and this has been termed ‘the commitment to sea-level rise’. The potential exposure to these changes, just based on today’s socio-economic conditions, is significant both regionally and globally (Table 6.12) and growing (Section 6.3.1). Thus there is a conflict between long-term sea-level rise and present-day human development patterns and migration to the coast (Nicholls et al., 2006).

The rate of sea-level rise is uncertain and a large rise (>0.6 m to 0.7 m/century) remains a low probability/high impact risk (Meehl et al., 2007). Some analyses suggest that protection would be an economically optimum response in most developed locations, even for an arbitrary 2 m/century scenario (Anthoff et al., 2006). However, sea-level rise will accumulate beyond 2100, increasing impact potential (Nicholls and Lowe, 2006). Further, there are several potential constraints to adaptation which are poorly understood (Section 6.4.3; Nicholls and Tol, 2006; Tol et al., 2006). This raises long-term questions about the implications of ‘hold the line’ versus ‘retreat the line’ adaptation policies and, more generally, how best to approach coastal spatial planning. While shoreline management is starting to address such issues for the 21st century (Eurosion, 2004; Defra, 2006), the long timescales of sea-level rise suggest that coastal management, including spatial planning, needs to take a long-term view on adaptation to sea-level rise and climate change, especially with long-life infrastructure such as nuclear power stations.

Table 6.12. Indicative estimates of regional exposure as a function of elevation and baseline (1995) socio-economics. MER – market exchange rates (after Anthoff et al., 2006).

 Exposure by factor and elevation above mean high water 
Region Land area (km2) Population (millions) GDP MER (US$ billions) 
 1m 5m 10m 1m 5m 10m 1m 5m 10m 
Africa 118 183 271 14 22 11 19 
Asia 875 1548 2342 108 200 294 453 843 1185 
Australia 135 198 267 38 51 67 
Europe 139 230 331 14 21 30 305 470 635 
Latin America 317 509 676 10 17 25 39 71 103 
North America 640 1000 1335 14 22 103 358 561 
Global (Total) 2223 3667 5223 145 268 397 944 1802 2570