IPCC Report.pdf - Adam Curry

Chapter 9Case Studiesbecause heat-related extreme events are projected to result in increasedmortality (Peng et al., 2010). Extreme heat events have been encounteredrecently in North America (Hawkins-Bell and Rankin, 1994; Klinenberg,2002), Asia (Kumar, 1998; Kalsi and Pareek, 2001; Srivastava et al., 2007),Africa (NASA, 2008), Australia (DSE, 2008b), and Europe (Robine et al.,2008; Founda and Giannakopoulos, 2009). This concern may also bepresent in non-temperate regions, but there is little research on this.As with other types of hazards, extreme heat events can have disastrousconsequences, partly due to increases in exposure and particular typesof vulnerabilities. However, it is important to note that reducing theimpacts of extreme heat events linked to climate change will necessitatefurther actions, some of which may be resource intensive and furtherexacerbate climate change.9.2.1.2.1. Vulnerabilities to heat wavesPhysiological: Several factors influence vulnerability to heat-relatedillness and death. Most of the research related to such vulnerability isderived from experiences in industrialized nations. Several physiologicalfactors, such as age, gender, body mass index, and preexisting healthconditions, play a role in the body’s ability to respond to heat stress. Olderpersons, babies, and young children have a number of physiological andsocial risk factors that place them at elevated risk, such as decreasedability to thermoregulate (the ability to maintain temperature within thenarrow optimal physiologic range; Havenith, 2001). Preexisting chronicdisease – more common in the elderly – also impairs compensatoryresponses to sustained high temperatures (Havenith, 2001; Shimoda,2003). Older adults tend to have suppressed thirst impulse resulting indehydration and increased risk of heat-related illness. In addition, multiplediseases and/or drug treatments increase the risk of dehydration(Hodgkinson et al., 2003; Ebi and Meehl, 2007).Social: A wide range of socioeconomic factors are associated withincreased vulnerability (see Sections 2.3 and 2.5). Areas with high crimerates, low social capital, and socially isolated individuals had increasedvulnerability during the Chicago heat wave in 1995 (Klinenberg, 2002).People in areas of low socioeconomic status are generally at higher riskof heat-related morbidity and mortality due to higher prevalence ofchronic diseases – from cardiovascular diseases such as hypertension topulmonary disease, such as chronic obstructive pulmonary disease andasthma (Smoyer et al., 2000; Sheridan, 2003). Minorities and communitiesof low socioeconomic status are also frequently situated in higher heatstress neighborhoods (Harlan et al., 2006). Protective measures areoften less available for those of lower socioeconomic status, and even ifair conditioning, for example, is available, some of the most vulnerablepopulations will choose not to use it out of concern over the cost (O’Neillet al., 2009). Other groups, like the homeless and outdoor workers, areparticularly vulnerable because of their living situation and being moreacutely exposed to heat hazards (Yip et al., 2008). Older persons may alsooften be isolated and living alone, and this may increase vulnerability(Naughton et al., 2002; Semenza, 2005).9.2.1.2.2. Impact of urban infrastructureAddressing vulnerabilities in urban areas will benefit those at risk.Around half of the world’s population live in urban areas at present, andby 2050, this figure is expected to rise to about 70% (UN, 2008). Citiesacross the world are expected to absorb most of the population growthover the next four decades, as well as continuing to attract migrants fromrural areas (UN, 2008). In the context of a heat-related extreme event,certain infrastructural factors can either amplify or reduce vulnerabilityof exposed populations. The built environment is important since local heatproduction affects the urban thermal budget (from internal combustionengines, air conditioners, and other activities). Other factors also play arole in determining local temperatures, including surface reflectivity oralbedo, the percent of vegetative cover, and thermal conductivity ofbuilding materials. The urban heat island effect, caused by increasedabsorption of infrared radiation by buildings and pavement, lack ofshading, evapotranspiration by vegetation, and increased local heatproduction, can significantly increase temperatures in the urban core byseveral degrees Celsius, raising the likelihood of hazardous heat exposurefor urban residents (Clarke, 1972; Shimoda, 2003). Street canyons wherebuilding surfaces absorb heat and affect air flow are also areas whereheat hazards may be more severe (Santamouris et al., 1999; Louka etal., 2002). The restricted air flow within street canyons may also causeaccumulation of traffic-related air pollutants (Vardoulakis et al., 2003).Research has also identified that, at least in the North American andEuropean cities where the phenomenon has been studied, these factorscan have a significant impact on the magnitude of heat hazards on aneighborhood level (Harlan et al., 2006). One study in France has shownthat higher mortality rates occurred in neighborhoods in Paris that werecharacterized by higher outdoor temperatures (Cadot et al., 2007). Hightemperatures can also affect transport networks when heat damagesroads and rail tracks. Within cities, outdoor temperatures can varysignificantly (Akbari and Konopacki, 2004), resulting in the need tofocus preventive strategies on localized characteristics.Systems of power generation and transmission partly explain vulnerabilitysince electricity supply underpins air conditioning and refrigeration – asignificant adaptation strategy particularly in developed countries, butone that is also at increased risk of failure during a heat wave (Sailorand Pavlova, 2003). It is expected that demand for electricity to powerair conditioning and refrigeration units will increase with rising ambienttemperatures. Areas with lower power capacities face increased risk ofdisruptions to generating resources and transmission under excessiveheat events.In addition to increased demand, there can be a risk of reduced outputfrom power generating plants (UNEP, 2004). The ability of inland thermalpower plants, both conventional and nuclear, to cool their generators isrestricted by rising river temperatures. Additionally, fluctuating levels ofwater availability will affect energy outputs of hydropower complexes.During the summer of 2003 in France, six power plants were shut downand others had to control their output (Parry et al., 2007).493