IPCC_Managing Risks of Extreme Events.pdf - Climate Access

Changes in Impacts of Climate Extremes: Human Systems and EcosystemsChapter 4of the developed world, societies are aging and hence can be moresensitive to climate extremes, such as heat waves (Hennessy et al.,2007). Heat extremes can claim casualties even in tropical countries,where people are acclimatized to the hot climate; McMichael et al.(2008) evaluated the relation between daily temperature and mortalityin middle- and low-income countries, and reported that higher mortalitywas observed on very hot days in most of the cities, including tropicalcities, such as Bangkok, Thailand; Delhi, India; and Salvador, Brazil.Floods can cause deaths and injuries and can be followed by infectiousdiseases (such as diarrhea) and malnutrition due to crop damage (seeSection 4.4.2.3). In Dhaka, Bangladesh, the severe flood in 1998 wasassociated with an increase in diarrhea during and after the flood, andthe risk of non-cholera diarrhea was higher among those from a lowersocioeconomic group and not using tap water (Hashizume et al., 2008).Floods may also lead to a geographical shift of malaria epidemicregions by changing breeding sites for vector mosquitoes. Outbreaks ofmalaria were associated with changes in habitat after the 1991 floods inCosta Rica’s Atlantic region (Saenz et al., 1995; for another example, seeCase Study 9.2.6). Malaria epidemics can also occur when people withlittle immunity move into endemic regions, although the displacementof large populations has rarely occurred as a result of acute naturaldisasters (Toole, 1997).Drought can affect water security, as well as food security throughreduction of agricultural production (MacDonald, 2010), and it can be afactor contributing to human-ignited forest fires, which can lead towidespread deforestation and carbon emissions (D’Almeida et al., 2007;van der Werf et al., 2008; Field et al., 2009; Phillips et al., 2009; Costaand Pires, 2010). Also, drought can increase or decrease the prevalenceof mosquito-borne infectious diseases such as malaria, depending on thelocal conditions (Githeko et al., 2000), and is associated with meningitis(Molesworth et al., 2003). Studies indicate that there is a climate signalin forest fires throughout the American West and Canada and that thereis a projected increase in severe wildfires in many areas (Gillett et al.,2004; Westerling et al., 2006; Westerling and Bryant, 2008). As describedby McMichael et al. (2003a), the direct effects of fire on human healthcan include burns and smoke inhalation, with indirect health impactspotentially resulting from loss of vegetation on slopes, increased soilerosion, and resulting increased risk of landslides.Evaluation of how impacts of climate extremes affect human health tendto focus on the direct, immediate effects of the event, using parametersthat are often easier to obtain and quantify like death statistics orhospitalizations. These direct observable outcomes are used todemonstrate the extremity of an event and as a comparison metric tomeasure against other extreme events. However, indirect health impactsare not often reported, because they are one step removed from theevent. Because indirect impacts are hard to monitor and are oftentemporally separated from the event, they are effectively removed fromthe cause-and-effect linkage to that event. Examples of indirect healthimpacts from extreme weather events include illnesses or injury resultingfrom disruption of human infrastructure built to deal with basic needs likemedical services; exposure to infectious or toxic agents after an extremeevent like cyclones or flooding (Schmid et al., 2005); stress, anxiety, andmental illness after evacuation or geographical displacement (Fritze etal., 2008) as well as increased susceptibility to infection (Yee et al.,2007); and disruption of socioeconomic structures and food productionthat leads to increases of malnutrition that might not manifest untilmonths after an extreme event (Haines et al., 2006; McMichael et al.,2006). Indirect health impacts are therefore a potentially large butunder-examined outcome of extreme weather events that lead to asubstantial underestimation of the total health burden.There is a growing body of evidence that the mental health impact fromextreme events is substantial (Neria et al., 2008; Berry et al., 2010).Often overshadowed by the physical health outcomes of an event, thepsychological effects can be long lasting and can affect a large portion ofa population (Morrissey and Reser, 2007). An extreme event may affectmental health directly from acute traumatic stress from an event, withcommon outcomes of anxiety and depression. It can also have indirectimpacts during the recovery period associated with the stress andchallenges of loss, disruption, and displacement. Furthermore, indirectmental health impacts could even affect individuals not directly associatedwith an event, like grieving friends and family of those who die from anevent or the rescue and aid workers who suffer post-traumatic stressdisorder (PTSD) after their aid efforts. Long-term mental health impactsare not often adequately monitored, but the body of research conductedafter natural disasters in the past three decades suggests that the burdenof PTSD among persons exposed to disasters is substantial (Neria et al.,2008). A range of other stress-related problems such as grief, depression,anxiety disorders, somatoform disorders, and drug and alcohol abuse(Fritze et al., 2008) have lasting effects, long after the causative event.There remain large limitations in evaluating health impacts of climatechange. The largest research gap is a lack of information on impactoutcomes themselves in developing countries in general. This includes themortality/morbidity data and information on other contributing factorssuch as nutritional status or access to safe water and medical facilities.4.4. Regionally Based Aspects ofVulnerability, Exposure, and Impacts4.4.1. IntroductionThe regional subsections presented here discuss the impacts of extremeweather and climate events within the context of other issues andtrends. Regional perspective, in social and economic dimensions, isimportant especially since decisionmaking often has a strong regionalcontext. For a comprehensive assessment of observed and projectedregional changes in climate extremes, see Sections 3.3 to 3.5 andTables 3-2 and 3-3.For various climate extremes, the following aspects are considered on aregional basis: exposure of humans and their activities to given climate252