| 英文摘要: | In southern Africa, the connections between climate and the water–energy–food nexus are strong. Physical and socioeconomic exposure to climate is high in many areas and in crucial economic sectors. Spatial interdependence is also high, driven, for example, by the regional extent of many climate anomalies and river basins and aquifers that span national boundaries. There is now strong evidence of the effects of individual climate anomalies, but associations between national rainfall and gross domestic product and crop production remain relatively weak. The majority of climate models project decreases in annual precipitation for southern Africa, typically by as much as 20% by the 2080s. Impact models suggest these changes would propagate into reduced water availability and crop yields. Recognition of spatial and sectoral interdependencies should inform policies, institutions and investments for enhancing water, energy and food security. Three key political and economic instruments could be strengthened for this purpose: the Southern African Development Community, the Southern African Power Pool and trade of agricultural products amounting to significant transfers of embedded water.
Numerous challenges coalesce to make southern Africa emblematic of the connections between climate and the water–energy–food nexus, which has important economic influence throughout the region. Physical and socioeconomic exposure to climate is high in socioeconomically vulnerable areas and crucial sectors, such as agriculture, but also in energy generation and mining. For example, almost 100% of electricity production in the Democratic Republic of Congo (DRC), Lesotho, Malawi and Zambia is from hydropower. Hydropower further comprises a major component of regional energy security through extensive sharing as part of the Southern African Power Pool (SAPP). The region's population is concentrated in areas exposed to high levels of hydrometeorological variability1 and is projected to roughly double by 20502. Of the 13 mainland countries and Madagascar (Table 1) that comprise the Southern African Development Community (SADC), six are defined as low income, three as lower-middle income and four as upper-middle income, according to the World Bank classification (using 2012 gross national income per capita). There are few quantified examples of the links between climate and economic activity in the region, although South Africa experienced a decrease in gross domestic product (GDP) in the 1983 El Niño year3, and economic modelling studies in Malawi and Zambia indicate that the severe 1992 drought caused a drop in GDP of approximately 7–9% and adversely affected household poverty4. Climate variability has important consequences for resource management in the region, including for non-equilibrium production systems such as rangeland ecology5, irrigation6 and lakes7. Southern Africa is also a region where seasonal climate forecasts can potentially benefit areas where sustained forecast skill is demonstrated. Seasonal climate forecasting has been the subject of many studies in sub-Saharan Africa (SSA)8, 9 and the Southern Africa Regional Climate Outlook Forum provides advance information about the likely character of seasonal climate. Yet, despite more than a decade of research on hydrological applications of seasonal forecasts, there is limited evidence of their operational use in the water sector9. With ongoing climate change, annual precipitation, soil moisture and runoff are likely to decrease, while rising temperatures could increase evaporative demand in large parts of the region10 (Fig. 1).
| http://www.nature.com/nclimate/journal/v5/n9/full/nclimate2735.html
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