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

6.6.2 Costs and benefits of adaptation

The body of information on costs of adaptation has increased dramatically since the TAR, covering the range from specific interventions to global aggregations. Most analyses quantify the costs of responses to the more certain and specific effects of sea-level rise. Selected indicative and comparative costs of coastal adaptation measures are presented in Table 6.11. They reveal a wide range in adaptation costs. But in most populated areas such interventions have costs lower than damage costs, even when just considering property losses (Tol, 2002, 2007). Climate change affects the structural stability and performance of coastal defence structures and hence significantly raises the costs of building new structures (Burgess and Townend, 2004) or upgrading existing structures (Townend and Burgess, 2004). Financial cost is not the only criterion on which adaptation should be judged – local conditions and circumstances might result in a more expensive option being favoured, especially where multiple benefits result.

Table 6.11. Selected information on costs and benefits of adaptation.

Optimal (benefit-cost) coastal protection costs and remaining number of people displaced given a 1 m rise in sea level (Tol, 2002) (see also Figure 6.11). 
Region Protection Costs (109 US$) Number of People Displaced (106)   
Africa 92 2.74   
OECD Europe 136 0.22   
World 955 8.61   
Construction costs for coastal defence in England and Wales (average total cost in US$/km) (Evans et al., 2004a) 
Earth embankment 970,000 Culverts 3.5 million 
Protected embankment 4.7 million Sea wall 4.7 million 
Dunes (excl. replenishment) 93,000 Groynes, breakwater (shingle beach)  9 million 
Costs (US$/km) to protect against 1 m in rise in sea level for the USA (Neumann et al., 2000) 
Dike or levee 450,000 – 2.4 million Sea wall; bulkhead construction 450,000 – 12 million 
Capital costs (US$/km) for selected coastal management options in New Zealand (Jenks et al., 2005) 
Sand dune replanting, with community input (maintenance costs minimal) 6,000 – 24,000 
Dune restoration, including education programmes (maintenance costs minimal) 15,000 – 35,000 
Dune reshaping and replanting (maintenance costs minimal) 50,000 – 300,000 
Sea walls and revetments (maintenance costs high – full rebuild every 20 – 40 years) 900,000 – 1.3 million 
Direct losses, costs and benefits of adaptation to 65 cm sea-level rise in Pearl Delta, China (Hay and Mimura, 2005)  
Tidal level Loss (US$ billion) Cost (US$ billion) Benefit (US$ billion) 
Highest recorded 5.2 0.4 4.8 
100 year high water 4.8 0.4 4.4