IPCC_Managing Risks of Extreme Events.pdf - Climate Access

Chapter 9Case StudiesThe development failures that have led to an accumulation of disasterrisk in Mumbai and allowed its transmission beyond the urban core arecommon to many other large urban centers. The IPCC FourthAssessment Report (AR4) stated with very high confidence that theimpact of climate change on coasts is exacerbated by increasinghuman-induced pressures, with subsequent studies being consistentwith this assessment (see Section 3.5.5).The AR4 also reported with very high confidence that coasts will beexposed to increasing risks, including coastal erosion, over comingdecades due to climate change and sea level rise, both of which will beexacerbated by increasing human-induced pressures (see Section 3.5.5).The July 2005 flooding in Mumbai underscores the fact that coastalmegacities are already at risk due to climate-related hazards (DeSherbinin et al., 2007; McGranahan et al., 2007). Refuse and debriscommonly clog storm drains, causing flooding even on the higherground in Mumbai’s slums, and landslides are another threat to squattercommunities that are near or on the few hillsides in the city (De Sherbininet al., 2007). Urban poor populations often experience increased ratesof infectious disease after flood events, and after the July 2005 floodsthe prevalence of leptospirosis rose eightfold in Mumbai (Maskey et al.,2006; Kovats and Akhtar, 2008).To the present, drivers of flood risk have been largely driven bysocioeconomic processes and factors, such as poverty, ecosystemdegradation, and poorly governed rapid urbanization (Revi, 2005, 2008;De Sherbinin et al., 2007; Huq et al., 2007; UNISDR, 2009c, 2011b;Hanson et al., 2011; Ranger et al., 2011). These processes are interrelated,and within these cities, vulnerability is concentrated in the poorestneighborhoods, which often lack access to sanitation, health care, andtransportation infrastructure, and whose homes and possessions areunprotected by insurance (Revi, 2005; De Sherbinin et al., 2007; UNISDR,2009c; Ranger et al., 2011).Slum settlements are often located in sites with high levels of risk dueto environmental and social factors. For example, they are often locatedin floodplains or on steep slopes, which means their residents suffer froma considerable degree of physical exposure and social vulnerability tolosses from flood events (Huq et al., 2007; McGranahan et al., 2007;Chatterjee, 2010).Mumbai is one of many coastal megacities that have been built in parton reclaimed land, a process that increases flood risks to low-lyingareas where slums are frequently located (Chatterjee, 2010). Its slumsdo not benefit from structural flood protection measures and are locatedin low-lying areas close to marshes and other marginal places andare frequently flooded during monsoon season, especially when heavyrainfall occurs during high tides (McGranahan et al., 2007; Chatterjee,2010). A rise in sea level of 50 cm, together with storm surges, wouldrender uninhabitable the coastal and low-lying areas (De Sherbinin etal., 2007) where many of Mumbai’s informal settlements are currentlylocated.9.2.8.4. Outcomes/ConsequencesIndia’s 2001 census indicated that in Mumbai 5,823,510 people (48.9%of the population) lived in slums (Government of India, 2001). In 2005,the global slum population was nearly 1 billion, and it is projectedto reach 1.3 to 1.4 billion by 2020, mostly concentrated in cities indeveloping countries (UN-HABITAT, 2006). In addition to Mumbai,Hanson et al. (2011) found that the following cities will have the greatestpopulation exposure to coastal flooding in 2070: Kolkata, Dhaka,Guangzhou, Ho Chi Minh City, Shanghai, Bangkok, Rangoon, Miami, andHai Phòng. Many of these cities are already characterized by significantpopulation and asset exposure to coastal flooding, and all but Miamiare located in developing countries in Asia.Africa does not have a large share of the world’s biggest coastal citiesbut most of its largest cities are on the coast and large sections of theirpopulation are at risk from flooding (Awuor et al., 2008; Adelekan, 2010).Compared to Asia, Europe, and the Americas, a greater percentage ofAfrica’s population lives in coastal cities of 100,000 to 5 million people,which is noteworthy because Africa’s medium-to-large cities tend to bepoor and many are growing at much higher rates than cities on theother continents (McGranahan et al., 2007).The amount of vulnerability concentrated within these cities will definetheir risks, and in the absence of adaptation there is high confidencethat locations currently experiencing adverse effects, such as coastalerosion and inundation, will continue to do so in the future (see Section3.5.5).However, there is a certain limit to adaptation given that these cities arefixed in place and some degree of exposure to hazards is ‘locked in’ dueto the unlikelihood of relocation (Hanson et al., 2011). For example, India’slarge infrastructure investments, which have facilitated Mumbai’s rapidgrowth, were built to last 50 to 150 years (Revi, 2008). This foreclosessome adaptation and DRR strategies, such as risk avoidance.Furthermore, all large coastal cities are centers of high populationdensity, infrastructure, investments, networking, and information(McGranahan et al., 2007; Chatterjee, 2010). This concentration andconnectivity make them important sources of innovation and economicgrowth, especially in developing countries where these ingredients maybe absent elsewhere. This underscores the importance of governanceand economic relations, including insurance and more general basicneeds of health and education, in allowing urban systems and those atrisk to build resilience if they cannot avoid hazard.9.2.8.5. Lessons IdentifiedMeasures to reduce exposure to existing weather-related hazards canalso serve as means of adapting to climate change (McGranahan et al.,2007; UNISDR, 2009c, 2011b; Chapters 1 and 2). At the time of the2005 flood, Mumbai lacked the capacity to address a complex portfolioof (interrelated) risks (De Sherbinin et al., 2007; Revi, 2008), and its511