ghana climate change vulnerability and adaptation assessment

6. VULNERABILITY TOCLIMATE CHANGEThe African continent is considered to be among the most likely to suffer adverse impacts of climate changebecause of vulnerable social and natural systems (Dixon, Smith et al. 2003), multiple interacting stresses, and lowadaptive capacity (Boko, Niang et al. 2007). Ghana spans a range of climatic and edaphic zones from coastalmangroves and rainforests along the coast to savanna in the north.The previous section described this variabilityin natural systems and livelihood strategies. The following discussion of vulnerability of natural and social systemsbuilds on this framework. In much of sub-Saharan Africa, precipitation is inherently variable from year to year.This is often expressed as recurrent drought and periodic flooding. Between 1991 and 2008 Ghana experiencedsix major floods with >2 million people affected by the floods in 1991 (GFDRR, undated). The northern savannazone is exposed to floods as well as drought. In 2007, floods followed a period of drought and affected >325,000people. In most of Africa, climate is a key driver of food security (Gregory, Ingram et al. 2005; Müller, Cramer etal. 2011). Because most agriculture is rain-fed and rural populations in many countries lack resources to moderateor adapt to drought (Dixon et al. 2003), the agricultural sector is particularly vulnerable (Haile 2005).The major findings for Africa of the Fourth Assessment Report of the IPCC confirm earlier reports, including awarming trend since the 1960s (Boko, Niang et al. 2007). In West Africa, rainfall has declined 20 percent to 40percent (average of 1968-1990 as compared to 1931-1960), although the decline in the tropical rainforest zone hasbeen only 4 percent (Malhi and Wright 2004). Despite advances in our understanding of the complex mechanismsdriving rainfall patterns, much uncertainty remains. Drought, a manifestation of extreme rainfall variability, haslong been a feature of the continental West African climate with severe and long-lasting impacts on natural andsocial systems. The decline in rainfall from the 1970s to the 1990s, for example, caused a 25-35 km southwardshift of the savanna zone (Sahelian, Sudanese, and Guinean savanna zones) with loss of grassland and woodlandand displacement of human populations (Gonzalez 2001). Besides long-term climatic trends and extreme events,ecosystems in West Africa have been degraded by human activity, which often interacts with climate. Majorstressors (drivers of degradation) are deforestation, wildfire, and soil erosion in upland areas and overfishing incoastal areas. In this chapter, we examine resource and social vulnerability.NATURAL SYSTEMS VULNERABILITYMost natural resources are climate-sensitive; plant and animal species are sensitive to weather extremes andcommunities are broadly distributed along climatic gradients. Soil resources are less sensitive to climate extremesbut develop over time within a climatic regime characterized by mean values. Thus, climate variability and changepotentially could affect these resources and the human communities that depend upon them. Here, we examineresource vulnerability at the national level in terms of climate hazards, stressors, resource systems, and outcome.We further categorize hazards as continuous or discrete; discrete hazards are further divided between those thatare recurrent or singular. Brooks (2003) provides the rationale for approaching hazards in this fashion, noting thatclimate hazards operate over different timescales that may require different adaptation responses. Continuoushazards relate to changes in mean climate over many years or decades, such as the decreased rainfall in thesavanna zones. Discrete recurrent hazards are transient, often extreme weather events such as storms, drought, orextreme rainfall events that lead to flooding. Discrete singular hazards are sudden shifts in climatic conditions thatprevail for centuries or millennia – for example, the onset of Ice Ages (Brooks, 2003). Contemporary exampleswould be the melting of the Greenland or west Antarctic ice sheets (Schneider, Semenov et al. 2007). In ourtreatment, we regard sea-level rise as such a singular event because it is best regarded as exceeding a thresholdlevel.GHANA CLIMATE CHANGE VULNERABILITY AND ADAPTATION ASSESSMENT 91