TURN DO WN THE H E AT: C L IM AT E E X T RE ME S , R EGION A L IMPA C TS, A N D TH E C A SE FOR R ESILIENCE
increases of 16 percent along the eastern and southeastern coast of Sub-Saharan Africa (Madagascar, Mozambique, Tanzania, and Kenya). However, for the same regions with closer proximity to the coast, yield changes of –16 to –5 percent are projected. Increases of more than 100 percent at the coast of Somalia and South Africa are projected. Apart from the southern coast of Angola, for the western African coast—where fish contributes as much as 50 percent of animal protein consumed (Lam, Cheung, Swartz, and Sumaila 2012)—significant adverse changes in maximum catch potential are projected of – 16 to –5 percent for Namibia, –31 to 15 percent for Cameroon and Gabon, and up to 50 percent for the coast of Liberia and Sierra Leone (Cheung et al. 2010). Lam et al. (2012), applying the same method and scenario, report decreases ranging from 52–60 percent, Côte d’Ivoire, Liberia, Togo, Nigeria, and Sierra Leone. The analysis by Cheung et al. (2010) does not account for changes in ocean acidity or oxygen availability. Oxygen availability has been found to decline in the 200–700m zone and is related to reduced water mixing due to enhanced stratification (Stramma, Schmidtko, Levin, and Johnson 2010). At the same time, warming waters lead to elevated oxygen demand across marine taxa (Stramma, Johnson, Sprintall, and Mohrholz 2008). Hypoxia is known to negatively impact the performance of marine organisms, leading to additional potential impacts on fish species (Pörtner 2010). Accordingly, a later analysis by Cheung, Dunne, Sarmiento, and Pauly (2011), which built on that of William Cheung et al (2010), found that acidification and a reduction of oxygen content in the northeast Atlantic ocean lowered the estimated catch potentials by 20–30 percent relative to simulations not considering these factors. Changes in catch potential can lead to decreases in local protein consumption in regions where fish is a major source of animal protein. For example, in their study of projected changes to fishery yields in West Africa by 2055 in a 2°C world, V. W. Y. Lam, Cheung, Swartz, and Sumaila (2012) compare projected changes in catch potential with projected protein demand (based on population growth, excluding dietary shifts). They show that in 2055 Ghana and Sierra Leone are expected to experience decreases of 7.6 percent and 7.0 percent respectively from the amount of protein consumed in 2000. Furthermore, they project economic losses of 21 percent of annual total landed value (from $732 million currently to $577 million, using constant 2000 dollars). Côte d’Ivoire, Ghana, and Togo, with up to 40 percent declines, are projected to suffer the greatest impacts on their land values. The job loss associated with projected declines in catches is estimated at almost 50 percent compared to the year 2000 (Lam et al. 2012). Of the whole of Sub-Saharan Africa, Malawi, Guinea, Senegal, and Uganda rank among the most vulnerable countries to climate-change-driven impacts on fisheries. This vulnerability is based on the combination of predicted warming, the relative importance of fisheries to national economies and diets, and limited adaptive capacity (Allison et al. 2009). 52
The vulnerability to impacts on marine ecosystems, however, differs from community to community. Cinner et al. (2012) measure the vulnerability to observed climate impacts on reef ecosystems in 42 communities across five western Indian Ocean countries (Kenya, Tanzania, Madagascar, Mauritius, and the Seychelles). The study provides evidence that not all sites are equally exposed to factors that cause bleaching. Reefs in Tanzania, Kenya, the Seychelles, and northwest Madagascar are found to experience more severe bleaching, while southwest Madagascar and Mauritius are less exposed because of lower seawater temperatures and UV radiation and higher wind velocity and currents. These findings caution against generalizations about the exposure of both ecosystems and the people dependent on them. The sensitivity of human communities to the repercussions of bleaching events is highest in those communities in Tanzania and parts of Kenya and Madagascar that are most dependent on fishing livelihoods.
Human Impacts Climate change impacts as outlined above are expected to have further repercussions for affected populations. Other impacts may also occur and interact with these to result in severe threats to human life. The human impacts of climate change will be determined by the socio-economic context in which they occur. The following sections discuss some of the identified risk factors to affected populations and the potential repercussions for society.
Human Health The increased prevalence of undernutrition is one of the most severe climate-related threats to human health in Sub-Saharan Africa. Insufficient access to nutrition already directly impacts human health, with high levels of undernutrition across the region. Undernutrition is the result of inadequate food intake or inadequate absorption or use of nutrients. The latter can result from diarrheal disease (Cohen, Tirado, Aberman, and Thompson 2008). Undernutrition increases the risk of secondary or indirect health implications because it heightens susceptibility to other diseases (World Health Organization 2009; World Bank Group 2009). It can also cause child stunting, which is associated with higher rates of illness and death and which can have long-term repercussions into adulthood, including reduced cognitive development (Cohen et al. 2008). In fact, undernutrition has been cited as the single most significant factor contributing to the global burden of disease; it is already taking a heavy toll, especially among children (IASC 2009). In Sub-Saharan Africa in 2011, the prevalence of undernourishment in the population ranges from 15–65 percent depending on the sub-region (Lloyd, Kovats, & Chalabi, 2011). Lloyd et al.