IPCC_Managing Risks of Extreme Events.pdf - Climate Access

Changes in Impacts of Climate Extremes: Human Systems and EcosystemsChapter 4air temperatures may increase evaporative water requirements in birds,thus influencing survival during extreme heat events (McKechnie andWolf, 2010). Heat waves could also cause increased likelihood ofcatastrophic avian mortality events (McKechnie and Wolf, 2010).4.3.3.2. DroughtA rapid, drought-induced die-off of overstory woody plants at asubcontinental scale was triggered by the 2000–2003 drought insouthwestern North America. Following 15 months of diminished soilwater content, more than 90% of the dominant tree species, Pinus edulis,died. Limited observations indicate that die-off was more extensive thanduring the previous drought of the 1950s, also affecting wetter siteswithin the tree species’ distribution (Breshears et al., 2005). Regionalscalepiñon pine mortality was observed following an extended drought(2000–2004) in northern New Mexico (Rich et al., 2008). Dominantplant species from diverse habitat types (i.e., riparian, chaparral, andlow-to high-elevation forests) exhibited significant mortality during adrought in the southwestern United States; average mortality amongdominant species was 3.3 to 41.4% (Gitlin et al., 2006).Evergreen coniferous species mortality caused by the coupling of droughtand higher temperatures from winter to spring has been observed in theRepublic of Korea (Lim et al., 2010). In 1998, 2002, 2007, and 2009, yearsof high winter-spring temperatures and lower precipitation, P. densifloraand P. koraiensis were affected by droughts, with many dying in thecrown layer, while deciduous species survived. Similarly, Abies koreana,an endemic species in Korea, at high elevation has declined following arise in winter temperatures since the late 1990s (Lim et al., 2010). Beechcrown condition was observed to decline following severe drought in1976 (Power, 1994), 1989 (Innes, 1992), and 1990 (Stribley andAshmore, 2002). Similarly, the percentage of moderately or severelydamaged trees displayed an upward trend after the 1989 drought inCentral Italy, especially for P. pinea and Fagus sylvatica (Bussotti et al.,1995). As final examples, defoliation and mortality in Scots pine observedin each year during 1996 to 2002 was related to the precipitation deficitand hot conditions of the previous year in the largest inner-alpinevalley of Switzerland (Valais) (Rebetez and Dobbertin, 2004), and bothgross primary production and total ecosystem respiration decreased in2003 in many regions of Europe (Granier et al., 2007).In a shallow temperate southern European estuary, the Mondego Estuaryin Portugal, the severe drought in 2004–2005 was responsible forspatial shifts in the estuary’s zooplankton community, with an increasein abundance and diversity during the period of low freshwater flow(Marques et al., 2007).4.3.3.3. FloodsFloods also impact ecosystems. Floods can cause population- andcommunity-level changes superimposed on a background of moregradual trends (Thibault and Brown, 2008). As an example, an extremeflood event affected a desert rodent community (that had beenmonitored for 30 years) by inducing a large mortality rate, eliminatingthe advantage of previously dominant species, resetting long-termpopulation and community trends, altering competitive and metapopulationdynamics, and reorganizing the community (Thibault andBrown, 2008).4.3.3.4. Other EventsOther events, such as hurricanes and storms, can also impact ecosystems.Hurricanes can cause widespread mortality of wild birds, and theiraftermath may cause declines due to the birds’ loss of resourcesrequired for foraging and breeding (Wiley and Wunderle, 1994). Winterstorms can also impact forest ecosystems, particularly in pre-alpine andalpine areas (Faccio, 2003; Schelhaas et al., 2003; Fuhrer et al., 2006). Inaddition, saltmarshes, mangroves, and coral reefs can be vulnerable toclimate extremes (e.g., Bertness and Ewanchuk, 2002; Hughes et al.,2003; Fischlin et al., 2007).4.3.4. Food Systems and Food SecurityFood systems and food security can be affected by extreme events thatimpair food production and food storage and delivery systems (foodlogistics). Impacts transmitted through an increase in the price of foodcan be especially challenging for the urban poor in developing countries(FAO, 2008). Global food price increases are borne disproportionally bylow-income countries, where people spend more of their income onfood (OECD-FAO, 2008).When agricultural production is not consumed where it is produced, itmust be transported and often processed and stored. This processinvolves complex interdependent supply chains exposed to multiplehazards. At every step of the process, transport and associatedinfrastructure such as roads, railways, bridges, warehouses, airports,ports, and tunnels can be at risk of direct damage from climateevents, making the processing and delivery chain as a whole at risk ofdisruption resulting from damage or blockages at any point in thechain.The economies of many developing countries rely heavily on agriculture,dominated by small-scale and subsistence farming. People’s livelihoodsin this sector are especially exposed to weather extremes (Easterlingand Apps, 2005; Easterling et al., 2007). Subsistence farmers can beseverely impacted by climate and weather events. For example, themajority of households produce maize in many African countries, butonly a modest proportion sells it – the great majority eat all theyproduce. In Kenya for example, nearly all households grow maize, butonly 36% sell it, with 20% accounting for the majority of sales (FAO,2009). Both such famers and their governments have limited capacityfor recovery (Easterling and Apps, 2005).246