990 resultados para Pan-African belt


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Objectives. The overarching aim of this paper is to consider the relationship between social entrepreneurship and rural development, and as a mechanism to address social exclusion in the Global South, with specific reference to Sub-Saharan Africa. Drawing upon a number of case examples of social purpose ventures in Kenya, Mozambique and Zambia the objectives of this paper are: - To provide a synthesis of existing literature on the interaction between social purpose ventures and rural BoP communities in the developing world; - To explore extant social exclusion literature including economic, political and international development dimensions; and - To analyse the case study examples to consider the channels through which social purpose ventures contribute to tackling social exclusion amongst the rural BoP. Prior Work. There is growing interest in the role that social enterprises and wider social purpose ventures can play in sustainable development in the Global South. In many developing countries the majority of the population still reside in rural areas with these areas often particularly marginalised and underdeveloped. Previous studies have provided anecdotal examples where social purpose ventures have the potential to provide innovative solutions to the development challenges faced by rural households and communities. Yet research in this area remains relatively nascent and fragmented. In depth empirical studies examining social purpose ventures and rural development in the Global South are furthermore limited. Approach. Data was collected during in-depth case study research with social purpose ventures in Zambia, Kenya and Mozambique. Cases were selected through a purposive sample with access negotiated to rural BoP communities through gatekeeper partners. Qualitative research methods were primarily employed including interviews, stakeholder focus groups and observational research. Results Six channels through which social purpose ventures contribute to tackling social exclusion amongst rural BoP communities are identified. These include ventures with the BoP as employees, producers, consumers, entrepreneurs, service users and shareholders. A number of shared characteristics for successful social purpose ventures are also outlined. Finally implications for policy, practice and research are discussed. Implications. Despite the increasing attention being given to social purpose ventures as a mechanism for global sustainable development many questions remain unanswered. Limited empirical work has been undertaken on such ventures operating in rural settings in the developing world, particularly Africa. The paper will add to academic and practitioner knowledge in this area especially in relation to up-scaling impact, the long term sustainability and viability of social purpose enterprise ventures, and effective supporting interventions. This paper adds to knowledge in the field of social purpose venturing in the developing world. It identifies various channels through which such ventures help tackle rural social exclusion and also factors influencing their success. The paper provides insights for practitioners and policy makers, particularly in relation to facilitating successful social purpose venturing. Value This paper will provide insights relevant to both academic and practitioner audiences. It addresses a subject area and geographical region that has received limited research attention to date. The paper adds to knowledge on social purpose ventures and social entrepreneurship in Africa and wider developing world environments, and contributes to debates on its potential and present limitations as a vehicle for development and societal transformation

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Seasonal-to-interannual predictions of Arctic sea ice may be important for Arctic communities and industries alike. Previous studies have suggested that Arctic sea ice is potentially predictable but that the skill of predictions of the September extent minimum, initialized in early summer, may be low. The authors demonstrate that a melt season “predictability barrier” and two predictability reemergence mechanisms, suggested by a previous study, are robust features of five global climate models. Analysis of idealized predictions with one of these models [Hadley Centre Global Environment Model, version 1.2 (HadGEM1.2)], initialized in January, May and July, demonstrates that this predictability barrier exists in initialized forecasts as well. As a result, the skill of sea ice extent and volume forecasts are strongly start date dependent and those that are initialized in May lose skill much faster than those initialized in January or July. Thus, in an operational setting, initializing predictions of extent and volume in July has strong advantages for the prediction of the September minimum when compared to predictions initialized in May. Furthermore, a regional analysis of sea ice predictability indicates that extent is predictable for longer in the seasonal ice zones of the North Atlantic and North Pacific than in the regions dominated by perennial ice in the central Arctic and marginal seas. In a number of the Eurasian shelf seas, which are important for Arctic shipping, only the forecasts initialized in July have continuous skill during the first summer. In contrast, predictability of ice volume persists for over 2 yr in the central Arctic but less in other regions.

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African societies are dependent on rainfall for agricultural and other water-dependent activities, yet rainfall is extremely variable in both space and time and reoccurring water shocks, such as drought, can have considerable social and economic impacts. To help improve our knowledge of the rainfall climate, we have constructed a 30-year (1983–2012), temporally consistent rainfall dataset for Africa known as TARCAT (TAMSAT African Rainfall Climatology And Time-series) using archived Meteosat thermal infra-red (TIR) imagery, calibrated against rain gauge records collated from numerous African agencies. TARCAT has been produced at 10-day (dekad) scale at a spatial resolution of 0.0375°. An intercomparison of TARCAT from 1983 to 2010 with six long-term precipitation datasets indicates that TARCAT replicates the spatial and seasonal rainfall patterns and interannual variability well, with correlation coefficients of 0.85 and 0.70 with the Climate Research Unit (CRU) and Global Precipitation Climatology Centre (GPCC) gridded-gauge analyses respectively in the interannual variability of the Africa-wide mean monthly rainfall. The design of the algorithm for drought monitoring leads to TARCAT underestimating the Africa-wide mean annual rainfall on average by −0.37 mm day−1 (21%) compared to other datasets. As the TARCAT rainfall estimates are historically calibrated across large climatically homogeneous regions, the data can provide users with robust estimates of climate related risk, even in regions where gauge records are inconsistent in time.

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Empowerment is a standard but ambiguous element of development rhetoric and so, through the socially complex and contested terrain of South Africa, this paper explores its potential to contribute to inclusive development. Investigating micro-level engagements with the national strategy of Broad-Based Black Economic Empowerment (B-BBEE) in the South African wine industry highlights the limitations, but also potential, of this single domain approach. However, latent paternalism, entrenched interests and a ‘dislocated blackness’ maintain a complex racial politics that shapes both power relations and the opportunities for transformation within the industry. Nonetheless, while B-BBEE may not, in reality, be broad-based its manifestations are contributing to challenging racist structures and normalising changing attitudes. This paper concludes that, to be transformative, empowerment needs to be re-embedded within South Africa as a multi-scalar, multi-dimensional dialogue and, despite the continuation of structural constraints, positions the local as a critical scale at which to initiate broader social change.

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This study evaluates model-simulated dust aerosols over North Africa and the North Atlantic from five global models that participated in the Aerosol Comparison between Observations and Models phase II model experiments. The model results are compared with satellite aerosol optical depth (AOD) data from Moderate Resolution Imaging Spectroradiometer (MODIS), Multiangle Imaging Spectroradiometer (MISR), and Sea-viewing Wide Field-of-view Sensor, dust optical depth (DOD) derived from MODIS and MISR, AOD and coarse-mode AOD (as a proxy of DOD) from ground-based Aerosol Robotic Network Sun photometer measurements, and dust vertical distributions/centroid height from Cloud Aerosol Lidar with Orthogonal Polarization and Atmospheric Infrared Sounder satellite AOD retrievals. We examine the following quantities of AOD and DOD: (1) the magnitudes over land and over ocean in our study domain, (2) the longitudinal gradient from the dust source region over North Africa to the western North Atlantic, (3) seasonal variations at different locations, and (4) the dust vertical profile shape and the AOD centroid height (altitude above or below which half of the AOD is located). The different satellite data show consistent features in most of these aspects; however, the models display large diversity in all of them, with significant differences among the models and between models and observations. By examining dust emission, removal, and mass extinction efficiency in the five models, we also find remarkable differences among the models that all contribute to the discrepancies of model-simulated dust amount and distribution. This study highlights the challenges in simulating the dust physical and optical processes, even in the best known dust environment, and stresses the need for observable quantities to constrain the model processes.

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Warm conveyor belts (WCBs) are the main ascending air masses within extratropical cyclones. They often exhibit strong condensation and precipitation, associated with ascent on large scales or embedded convection. Most of the air outflows into the upper troposphere as part of a ridge. Such ridges are an integral part of Rossby waves propagating along the tropopause and are identified with a negative potential vorticity (PV) anomaly and associated anticyclonic circulation. It has been argued that diabatic modification of PV in WCBs has an important influence on the extent of the ridge, propagation of Rossby waves and weather impacts downstream. Following the coherent ensemble of trajectories defining a WCB, PV is expected to increase with time while below the level of maximum latent heating and then decrease as trajectories ascend above the heating maximum. In models, it is found that the net change is approximately zero, so that the average PV of the WCB outflow is almost equal to the PV of its inflow. Here, the conditions necessary for this evolution are explored analytically using constraints arising from the conservation of circulation. It is argued that the net PV change is insensitive to the details of diabatic processes and the PV maximum midway along a WCB depends primarily on the net diabatic transport of mass from the inflow to the outflow layer. The main effect of diabatic processes within a WCB is to raise the isentropic level of the outflow, rather than to modify PV.

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Fossil pollen, ancient lake sediments and archaeological evidence from Africa indicate that the Sahel and Sahara regions were considerably wetter than today during the early to middle Holocene period, about 12,000 to 5,000 years ago1–4. Vegetation associated with the modern Sahara/Sahel boundary was about 5° farther north, and there were more and larger lakes between 15 and 30° N. Simulations with climate models have shown that these wetter conditions were probably caused by changes in Earth's orbital parameters that increased the amplitude of the seasonal cycle of solar radiation in the Northern Hemisphere, enhanced the land-ocean temperature contrast, and thereby strengthened the African summer monsoon5–7. However, these simulations underestimated the consequent monsoon enhancement as inferred from palaeorecords4. Here we use a climate model to show that changes in vegetation and soil may have increased the climate response to orbital forcing. We find that replacing today's orbital forcing with that of the mid-Holocene increases summer precipitation by 12% between 15 and 22° N. Replacing desert with grassland, and desert soil with more loamy soil, further enhances the summer precipitation (by 6 and 10% respectively), giving a total precipitation increase of 28%. When the simulated climate changes are applied to a biome model, vegetation becomes established north of the current Sahara/Sahel boundary, thereby shrinking the area of the Sahara by 11% owing to orbital forcing alone, and by 20% owing to the combined influence of orbital forcing and the prescribed vegetation and soil changes. The inclusion of the vegetation and soil feedbacks thus brings the model simulations and palaeovegetation observations into closer agreement.

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Weather and climate model simulations of the West African Monsoon (WAM) have generally poor representation of the rainfall distribution and monsoon circulation because key processes, such as clouds and convection, are poorly characterized. The vertical distribution of cloud and precipitation during the WAM are evaluated in Met Office Unified Model simulations against CloudSat observations. Simulations were run at 40-km and 12-km horizontal grid length using a convection parameterization scheme and at 12-km, 4-km, and 1.5-km grid length with the convection scheme effectively switched off, to study the impact of model resolution and convection parameterization scheme on the organisation of tropical convection. Radar reflectivity is forward-modelled from the model cloud fields using the CloudSat simulator to present a like-with-like comparison with the CloudSat radar observations. The representation of cloud and precipitation at 12-km horizontal grid length improves dramatically when the convection parameterization is switched off, primarily because of a reduction in daytime (moist) convection. Further improvement is obtained when reducing model grid length to 4 km or 1.5 km, especially in the representation of thin anvil and mid-level cloud, but three issues remain in all model configurations. Firstly, all simulations underestimate the fraction of anvils with cloud top height above 12 km, which can be attributed to too low ice water contents in the model compared to satellite retrievals. Secondly, the model consistently detrains mid-level cloud too close to the freezing level, compared to higher altitudes in CloudSat observations. Finally, there is too much low-level cloud cover in all simulations and this bias was not improved when adjusting the rainfall parameters in the microphysics scheme. To improve model simulations of the WAM, more detailed and in-situ observations of the dynamics and microphysics targeting these non-precipitating cloud types are required.

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Growing criticism of Chinese engagement in Africa centres on the risk to African development posed by China's aggressive export policies and the threat to the Washington Consensus and African governance posed by China's 'non-interference' approach to engagement. This article challenges both these assumptions. The growth of Chinese trade has a wide range of impacts, depending on the sector in question, and the current terms of trade Washington extends to Africa under the auspices of the AGOA do not result in uniformly beneficial effects. With regard to African governance, it is argued that the 'Washington Consensus' has been based on competing and often muddled perceptions of US national interest. This fact tempers the regret felt at Washington's loss of influence over the good governance agenda. Evidence is provided to show that China can work within properly regulated countries and industries, if the African governments in question can provide fair, efficient and transparent environments in which to operate.

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The spatial pattern of precipitation variability in tropical and subtropical Africa over the late Quaternary has long been debated. Prevailing hypotheses variously infer (1) insolation-controlled asymmetry of wet phases between hemispheres, (2) symmetric contraction and expansion of the tropical rainbelt, and (3) independent control on moisture available in Southern Africa via sea surface temperatures in the Indian Ocean. In this study we use climate-model simulations covering the last glacial cycle (120 kyr) with HadCM3 and the multi-model ensembles from PMIP3 (the Palaeoclimate Model Intercomparison Project) to investigate the long-term behaviour of the African rainbelt, and test these simulations against existing empirical palaeohydrological records. Through regional model-data comparisons we find evidence for the validity of several hypotheses, with various proposed processes occurring concurrently but with different regional emphasis (e.g. asymmetric shifts at the seasonal extremes and symmetric expansions/ contractions towards West equatorial regions). Crucially, variations in rainfall are associated with multiple forcing mechanisms that vary in their dominance both spatially and temporally over the glacial cycle; an important consideration when interpreting and extrapolating from often relatively short palaeoenvironmental records.

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Working outward from Edward Kamau Brathwaite’s landmark 1974 essay, “The African Presence in Caribbean Literature,” this article explores the fuller history of the idea of Africa in anglophone Caribbean critical and literary works from the 1930s to the 2000s. It demonstrates that earlier, now forgotten Caribbean critics drew on imperfect and incomplete Caribbean literary imaginings of Africa to frame a counter-colonial politics of identity. The essay also brings back into view writings by Una Marson, Victor Stafford Reid, and Derek Walcott that expressed a different politics of solidarity based on the shared experience of colonial violence. Readings of recent literary works by Charlotte Williams and Nalo Hopkinson reveal the contemporary crafting of this relation around a heightened awareness of both presence and loss, history and imagination. Importantly, this gathering of sources and perspectives allows for an appreciation of the role that a reach toward Africa has played in articulations of Caribbeanness and its complex patterning of cultural co-belonging.

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In this paper, we construct a dynamic portrait of the inner asteroidal belt. We use information about the distribution of test particles, which were initially placed on a perfectly rectangular grid of initial conditions, after 4.2 Myr of gravitational interactions with the Sun and five planets, from Mars to Neptune. Using the spectral analysis method introduced by Michtchenko et al., the asteroidal behaviour is illustrated in detail on the dynamical, averaged and frequency maps. On the averaged and frequency maps, we superpose information on the proper elements and proper frequencies of real objects, extracted from the data base, AstDyS, constructed by Milani and Knezevic. A comparison of the maps with the distribution of real objects allows us to detect possible dynamical mechanisms acting in the domain under study; these mechanisms are related to mean-motion and secular resonances. We note that the two- and three-body mean-motion resonances and the secular resonances (strong linear and weaker non-linear) have an important role in the diffusive transportation of the objects. Their long-lasting action, overlaid with the Yarkovsky effect, may explain many observed features of the density, size and taxonomic distributions of the asteroids.