ghana climate change vulnerability and adaptation assessment

however, many valuable timber trees were retained in cocoa fields, augmented by planting of fruit and otheruseful trees; thus, shade-grown cocoa was an agroforestry practice with greater biodiversity value than slashand burn agriculture (Duguma, Gockowski et al. 2001) and full sun cocoa farming.Cocoa yields in Ghana are below international averages; the potential increase from higher productivity couldbe more than double the yields in 2005 (FAO 2005; Breisinger, Diao et al. 2008). Increases could come fromnew varieties and increased use of fertilizer. Newer varieties have been shown to increase yields by at least 42percent and fertilizer use was associated with 19 percent higher cocoa yield per 50 kg bag of fertilizer (Edwinand Masters 2005). Research has demonstrated the technical advantages of fertilized, low shade or full sunhybrids and current recommendations from the Cocoa Research Institute of Ghana call for additions ofphosphorus, potassium, and micronutrient fertilizer, densely planted hybrid cocoa (1,111 trees ha -1 ), whileretaining at most 12-15 shade trees ha -1 (Gockowski and Sonwa). In practice, smallholders have been able toadopt only the low shade/full sun recommendation as they lack resources to acquire hybrid seeds andfertilizer. Little research has been directed towards increasing productivity of traditional shade grown cocoa(Gockowski and Sonwa ; Breisinger, Diao et al. 2008) although that is an alternative that would avoid thenegative effects of full sun hybrid cocoa on biodiversity (Belsky and Siebert 2003; Franzen and BorgerhoffMulder 2007).EFFECTS OF CLIMATE CHANGE ON AGRICULTURECrops are vulnerable to climate variability as evidenced most obviously by lowered yields during droughtperiods, less dramatically by year-to-year variation in productivity. Variability can take many forms; forexample less total annual precipitation, delayed onset of the rainy period, higher temperature or sub-optimummoisture during critical growth stages (too moist during establishment might favor diseases, such as dampingoff; too dry during grain-filling might lower yield). Changes in average climate values in regions currently atthe limit for growing some crops could reduce yields to non-viable levels, for example, causing a shift towardsagropastoral systems. The complexity of crop growth requires climate data (short-term variability, frequencyof extreme events) at spatial and temporal resolutions that are currently beyond the reach of climate changemodels (Challinor, Wheeler et al. 2007). In addition to inadequate climate models, crop modeling research hasfavored the major global food crops and devoted less attention to crops important to Ghana, such as milletand yams. Additionally, crop models generally are specified for monocropping and rarely considerintercropping. Improvements in both climate and crop models and the ability to model effects at scales fromthe farmer’s field to the region and nation will be critical to formulating adaptation options for agriculture andmainstreaming climate change into development programs (Challinor, Wheeler et al. 2007).Several assessments have been made of the potential effect of climate change on crop yields in Africa(Challinor, Wheeler et al. 2007). They are not readily compared because they use different global circulationmodels, IPCC emission scenarios, and crop models, but they generally indicate negative effects for maize,rice, millet and cereals in general; effects range from +16 percent to -98 percent change in annual yields(Challinor, Wheeler et al. 2007). Linking five climate models and five emissions scenarios with a spatiallyexplicit agro-ecosystem model and a global food system (trade) model provided an integrated system toexamine not only climate change effects on agriculture but the effects of limited agronomic adaptation(Fischer, Shah et al. 2005). Effects of climate change on agricultural production were relatively minor globallybut significant regionally. Ghana was projected to gain cereal-production potential by 2080, depending uponemission scenario (Fischer, Shah et al. 2005) but generally, semi-arid zones within sub-Saharan Africa (such asthe northern savanna zones in Ghana) would experience reductions in cereal-crop production (Fischer, Shahet al. 2005; Zhang and Cai 2011).72 GHANA CLIMATE CHANGE VULNERABILITY AND ADAPTATION ASSESSMENT