The 21st Century climate challenge

enign climate change scenarios point to deepvulnerabilities.Small-island developing states are on thefront line of climate change. They are alreadyhighly vulnerable to climate disasters. Annualdamages for the Pacific islands of Fiji, Samoaand Vanuatu are estimated at 2–7 percent ofGDP. In Kiribati, one estimate of the combinedannual damage bill from climate change andsea-level rises in the absence of adaptation putsthe figure at a level equivalent to 17–34 percentof GDP. 90Islands in the Caribbean are also at risk.With a 50 centimetre increase in sea levels, overone-third of the Caribbean’s beaches wouldbe lost, with damaging implications for theregion’s tourist industry. An increase of 1 metrewould permanently submerge about 11 percentof the land area in the Bahamas. Meanwhile,the intrusion of salt water would compromisefreshwater supplies, forcing governments toundertake costly investments in desalination. 91More intense tropical storm activity is oneof the givens of climate change. Warming seaswill fuel more powerful cyclones. At the sametime, higher sea temperatures and wider climatechange may also alter the course of cyclonetracks and the distribution of storm activity.The first-ever hurricane in the South Atlanticstruck Brazil in 2004, and 2005 marked thefirst hurricane to hit the Iberian peninsula sincethe 1820s.Scenarios for tropical storm activity demonstratethe importance of interactions withsocial factors. In particular, rapid urbanizationis placing a growing population in harm’s way.Approximately 1 billion people already live ininformal urban settlements, and numbers arerising. UN-HABITAT estimates that if currenttrends continue there will be 1.4 billion peopleliving in slums by 2020 and 2 billion by 2030:one in every three urban dwellers. While morethan half the world’s slum population todaylives in Asia, sub-Saharan Africa has some ofthe world’s fastest growing slums. 92Living in makeshift homes often located onhillsides vulnerable to flooding and landslides,slum dwellers are both highly exposed andhighly vulnerable to climate change impacts.Table 2.5 Rising sea levels would have large social and economic impactsMagnitude of sealevel rise (m) Land area Population GDP Urban areaAgriculturalareaWetlandarea1 0.3 1.3 1.3 1.0 0.4 1.92 0.5 2.0 2.1 1.6 0.7 3.03 0.7 3.0 3.2 2.5 1.1 4.34 1.0 4.2 4.7 3.5 1.6 6.05 1.2 5.6 6.1 4.7 2.1 7.3Source: Dasgupta et al. 2007.These impacts will not be determined purelythrough physical processes. Public policiescan improve resilience in many areas, rangingfrom flood control to infrastructural protectionagainst landslides and the provision of formalsettlement rights to urban slum dwellers.In many cases the absence of formal rightsis a deterrent to investment in more robustbuilding materials.Climate change will create mountingthreats. Even robust mitigation will do littleto lessen those threats until 2030. Until then,the urban poor will have to adapt to climatechange. Supportive public policies could helpthat adaptation. The starting points: creatingmore secure tenure rights, investing in slumupgrading and providing clean water andsanitation to the urban poor.Ecosystems and biodiversityIPCC projection: There is a high confidenceprobability that the resilience of many ecosystemswill be undermined by climate change,with rising CO 2levels reducing biodiversity,damaging ecosystems and compromising theservices that they provide.Human development projection: Theworld is heading towards unprecedentedlosses of biodiversity and the collapse ofecological systems during the 21 st Century.At temperature increases in excess of 2°C,rates of extinction will start to increase.Environmental degradation will gather pace,with coral, wetland and forest systems sufferingrapid losses. The processes are already underImpact (% of global total)2Climate shocks: risk and vulnerability in an unequal worldHUMAN DEVELOPMENT REPORT 2007/2008 101