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

6.6.3 Limits and trade-offs in adaptation

Recent studies suggest that there are limits to the extent to which natural and human coastal systems can adapt even to the more immediate changes in climate variability and extreme events, including in more developed countries (Moser, 2005; Box 6.6). For example, without either adaptation or mitigation, the impacts of sea-level rise and other climate change such as more intense storms (Section 6.3.2) will be substantial, suggesting that some coastal low-lying areas, including atolls, may become unviable by 2100 (Barnett and Adger, 2003; Nicholls, 2004), with widespread impacts in many other areas. This may be reinforced by risk perception and disinvestment from these vulnerable areas. Adaptation could reduce impacts by a factor of 10 to 100 (Hall et al., 2006; Tol, 2007) and, apart from some small island nations, this appears to come at a minor cost compared to the damage avoided (Nicholls and Tol, 2006). However, the analysis is idealised, and while adaptation is likely to be widespread, it remains less clear if coastal societies can fully realise this potential for adaptation (see Box 6.6).

Adaptation for present climate risks is often inadequate and the ability to manage further increases in climate-related risks is frequently lacking. Moreover, increases in coastal development and population will magnify the risks of coastal flooding and other hazards (Section 6.2.2; Pielke Jr et al., 2005). Most measures to compensate and control the salinisation of coastal aquifers are expensive and laborious (Essink, 2001). Frequent floods impose enormous constraints on development. For example, Bangladesh has struggled to put sizeable infrastructure in place to prevent flooding, but with limited success (Ahmad and Ahmed, 2003). Vietnam’s transition from state central planning to a more market-oriented economy has had negative impacts on social vulnerability, with a decrease in institutional adaptation to environmental risks associated with flooding and typhoon impacts in the coastal environment (Adger, 2000). In a practical sense adaptation options for coral reefs are limited (Buddemeier, 2001) as is the case for most ecosystems. The continuing observed degradation of many coastal ecosystems (Section 6.2.2), despite the considerable efforts to reverse the trend, suggests that it will also be difficult to alleviate the added stresses resulting from climate change.

Knowledge and skill gaps are important impediments to understanding potential impacts, and thus to developing appropriate adaptation strategies for coastal systems (Crimp et al., 2004). The public often has conflicting views on the issues of sustainability, hard and soft defences, economics, the environment and consultation. Identifying the information needs of local residents, and facilitating access to information, are integral components in the process of public understanding and behavioural change (Myatt et al., 2003; Moser, 2005, 2006; Luers and Moser, 2006).

There are also important trade-offs in adaptation. For instance, while hard protection can greatly reduce the impacts of sea level and climate change on socio-economic systems, this is to the detriment of associated natural ecosystems due to coastal squeeze (Knogge et al., 2004; Rochelle-Newall et al., 2005). Managed retreat is an alternative response, but at what cost to socio-economic systems? General principles that can guide decision making in this regard are only beginning to be developed (Eurosion, 2004; Defra, 2006). Stakeholders will be faced with difficult choices, including questions as to whether traditional uses should be retained, whether invasive alien species or native species increasing in abundance should be controlled, whether planned retreat is an appropriate response to rising relative sea level or whether measures can be taken to reduce erosion. Decisions will need to take into account social and economic as well as ecological concerns (Adam, 2002). Considering these factors, the US Environmental Protection Agency is preparing sea-level rise planning maps that assign all shores along its Atlantic Coast to categories indicating whether shore protection is certain, likely, unlikely, or precluded by existing conservation policies (Titus, 2004). In the Humber estuary (UK) sea-level rise is reducing the standard of protection, and increasing erosion. Adaptation initiatives include creation of new intertidal habitat, which may promote more cost-effective defences and also helps to offset the loss of protected sites, including losses due to coastal squeeze (Winn et al., 2003).

Effective policies for developments that relate to the coast are sensitive to resource use conflicts, resource depletion and to pollution or resource degradation. Absence of an integrated holistic approach to policy-making, and a failure to link the process of policy-making with the substance of policy, results in outcomes that some would consider inferior when viewed within a sustainability framework (Noronha, 2004). Proponents of managed retreat argue that provision of long-term sustainable coastal defences must start with the premise that “coasts need space” (Rochelle-Newall et al., 2005). Some argue that governments must work to increase public awareness, scientific knowledge, and political will to facilitate such a retreat from the “sacrosanct” existing shoreline (Pethick, 2002). Others argue that the highest priority should be the transfer of property rights in lesser developed areas, to allow for changing setbacks in anticipation of an encroaching ocean. This makes inland migration of wetlands and beaches an expectation well before the existing shoreline becomes sacrosanct (Titus, 2001). Property rights and land use often make it difficult to achieve such goals, as shown by the post-Katrina recovery of New Orleans. Economic, social, ecological, legal and political lines of thinking have to be combined in order to achieve meaningful policies for the sustainable development of groundwater reserves and for the protection of subsurface ecosystems (Danielopol et al., 2003). Socio-economic and cultural conditions frequently present barriers to choosing and implementing the most appropriate adaptation to sea-level rise. Many such barriers can often be resolved by way of education at all levels, including local seminars and workshops for relevant stakeholders (Kobayashi, 2004; Tompkins et al., 2005a). Institutional strengthening and other interventions are also of importance (Bettencourt et al., 2005).