Browsing by Subject "East Africa"

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    Open Access
    Madagascar: A pacemaker for the Agulhas Current system?
    (2006) Penven, P; Lutjeharms, J R E; Florenchie, P
    [1] Western boundary currents are driven by zonally integrated wind-stress curl over the width of subtropical basins. This cross-basin integration is interrupted in the South Indian Ocean where Madagascar presents a formidable barrier. Nevertheless, a western boundary current has been thought to exist in the Mozambique Channel, the Mozambique Current. Recent observations have however shown that no such current exists and that the flow in the channel instead consists of a train of eddies. Is this western boundary anomaly due to the presence of Madagascar? We have used a primitive equations model to investigate the flow in the South West Indian Ocean as if there were no Madagascar. We show that a normal, continuous western boundary current is then formed that constitutes a continuum with the Agulhas Current. The presence of Madagascar is shown to affect the frequency of inter-ocean exchange events south of Africa.
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    Open Access
    Simulating the impact of climate change on maize production in Ethiopia, East Africa
    (Springer Berlin Heidelberg, 2018-02-13) Abera, Kidist; Crespo, Olivier; Seid, Jemal; Mequanent, Fasil
    Background: Climate change is expected to signifcantly impact agricultural production across Africa. While a number of studies assessed this impact in semi-arid southern Africa, or tropical West Africa, only a limited number took interest in the mountainous and climatically varying Ethiopia of eastern Africa. This study assesses the impact of climate change on maize production in three representative sites of maize growing areas in Ethiopia. The assessment relies on the DSSAT crop model simulation of maize under current climate and future projections (19 Global Climate Models and 2 Representative Concentration Pathways). The period 1980–2010 was used to represent the baseline climate, while future climate projections cover three periods; near term (2010–2039), mid-century (2040–2069) and end-of-century (2070–2099). Climate, soil and crop management data were collected for the study sites representing the maize growing areas in the country. Results: Results show that maize yields will decrease by up to 43 and 24% by the end of the century at Bako and Melkassa stations, respectively, while simulated maize yield in Hawassa show an increase of 51%. On the one hand, rainfall variability and rising temperatures are determining factors explaining yield decrease in Bako and Melkassa, while projected rainfall increase in Hawassa explain simulated yield increases. Conclusion: The terrain and climate high variability of Ethiopia is emphasizing the extremely diferent responses of current agricultural systems to climate change. Though adaptation approached can address some negative impacts, and in some case can take advantage of changes, this study reveals that dedicated local knowledge is necessary for national and regional decision makers to respond with local relevance to a global exposure, in order to face food security challenges.
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    The myth of the East African 'Bushmen'
    (2003) Morris, Alan G
    Recent genetic studies of living African peoples have suggested that the KhoiSan in particular are of very ancient stock and that they share some ancient genetic features with living East Africans. Archaeological and linguistic evidence for an ancient KhoiSan presence in East Africa has been used to support these arguments. A re-examination of the archaeological evidence does not support this stance. In particular, the bulk of the osteological evidence for KhoiSan presence in East Africa is flawed because it is drawn from a typological context where individual osteological features were interpreted as KhoiSan and the total morphological pattern was not considered. More recent studies of archaeological specimens and living East Africans have not confirmed any KhoiSan linkage with East Africa. Linguistic evidence is also equivocal and the clicks found in East Africa may represent the remains of ancient linguistic phonemes rather than remnants of KhoiSan languages. Without the support of archaeological and linguistic evidence, the genetic similarities of East and South Africans should be seen as a more distant commonality of underlying genetic features of all Africans rather than a specific KhoiSan genetic identity. (The terminology used in this paper conforms to that of Jenkins & Tobias [1977]. The spelling of KhoiSan was adopted by the session on Nomenclature of People at the Origins of Humanity Workshop at Stellenbosch in September 2002 as part of the HSRC Africa Genome Initiative.)