1,720,980 research outputs found
Misperception of drivers of risk alters willingness to adapt in the case of sargassum influxes in West Africa
No full textSince 2011, large influxes of a brown macroalgae (pelagic sargassum seaweed) have proliferated across the Tropical Atlantic basin, its dispersal and seasonality theorized to be driven by localized and large scale winds and currents, in combination with changes in the Atlantic Meridional Mode and ocean upwelling. These influxes seasonally affect coastal populations across the breadth of the Tropical Atlantic (from central America to West Africa), causing damage to: economies, marine-based and non-marine coastal livelihoods, social functioning, health, ecology, and the aesthetics of the local environment. We use the ongoing sargassum influx in West Africa as a case study of adaptation to an emergent (and compound) risk in progress that also contributes to the empirical gap in sargassum adaptation research in West Africa. The research, in four sites in the Western Region of Ghana employs data from 16 focus group discussions, six key informant interviews, and participant observation. We finds that due to a series of coincidences, participant communities perceive that sargassum influxes were seeded by and then annually driven by oil and gas exploration in Western Ghana. This is in contrast to scientific research that indicates that pelagic sargassum was initially seeded in the tropical Atlantic basin (from the Sargasso Sea) in 2010 following an anomalous weather event in winter 2009–2010. Following Rogers’ Protection Motivation Theory, we explore the sources of information and the processing of that information to understand the divergence between scientific and community perceptions of the physical drivers. We find that community perceptions of oil and gas company responsibility for causing the sargassum problem leads the communities to perceive that the oil and gas companies should be responsible for the clean-up activities. Communities are further constrained by a perceived lack of capacity to act. Solutions to address this adaptation impasse could involve the government working with communities and the oil and gas industry to clarify the actual drivers of sargassum. Such guidance may open opportunities for the government and industry to work with communities to address misperceptions of the scientific nature of the influxes. Collaborative approaches, while addressing extant tensions, may also change the narrative about the problem, support affected communities to engage with adaptive measures, including re-use opportunities, and enhance community capacity to act. As a present-day emergent risk, pelagic sargassum provides an unusual yet contemporary empirical study of real-time adaptation and the central role of perceptions in shaping proactive adaptation and seeking exploitable opportunities from new environmental risks
Fluvial sediment supply and relative sea-level rise
No full textThe world’s deltas are facing a sustainability crisis, with many at high risk of being ‘drowned’ as a result of relative sea-level rise. The only factor that can potentially offset relative sea-level rise is the deposition of fluvial sediment on the surface of deltas. As a result, an understanding of trends in fluvial sediment supply to deltas is critical for understanding the potential of different deltas to adapt to the threat of drowning. Here trends of sediment supply to three of the world’s deltas (the Ganges-Brahmaputra, Mahanadi and Volta) are considered and the prospects for the future of these and other deltas discussed, focusing on how human activity can be modified to promote a more sustainable future for at-risk deltas
Assessing the impact of sea-level rise on a vulnerable coastal community in Accra, Ghana
No full textClimate change and its associated sea-level rise are expected to significantly affect vulnerable coastal communities. Although the extent of the impact will be localised, its assessment will adopt a monitoring approach that applies globally. The topography of the beach, the type of geological material and the level of human intervention will determine the extent of the area to be flooded and the rate at which the shoreline will move inland. Gleefe, a coastal community in Ghana, has experienced frequent flooding in recent times due to the increasing occurrence of storm surge and sea-level rise. This study used available geospatial data and field measurements to determine how the beach topography has contributed to the incidence of flooding at Gleefe. The topography is generally low-lying. Sections of the beach have elevations of around 1 m, which allows seawater to move inland during very high tide. Accelerated sea-level rise as predicted by the Intergovernmental Panel on Climate Change (IPCC) will destroy homes of the inhabitants and inundate the Densu wetlands behind the beach. Destruction of infrastructure will render the inhabitants homeless, whilst flooding of the wetlands will destroy the habitats of migratory birds and some endangered wildlife species such as marine turtle. Effective adaptation measures should be adopted to protect this very important coastal environment, the ecology of the wetlands and the livelihoods of the community dwellers.https://doi.org/10.4102/jamba.v5i1.6
Seasonal predictions of holopelagic sargassum across the Tropical Atlantic accounting for uncertainty in drivers and processes: The SARTRAC ensemble forecast system
No full textThe holopelagic macroalgae sargassum has proliferated across the tropical Atlantic since 2011, of consequence for coastal populations from West Africa to the Caribbean with limited early warning of major beaching events. As part of an interdisciplinary project, ‘Teleconnected SARgassum risks across the Atlantic: building capacity for TRansformational Adaptation in the Caribbean and West Africa’ (SARTRAC), an ensemble forecast system, SARTRAC-EFS, is providing seasonal predictions of sargassum drift. An eddy-resolving ocean model hindcast provides the winds and currents necessary to generate ensemble members. Ensemble forecasts are then obtained for different combinations of ‘windage’, the fractional influence of winds on sargassum mats, and in situ rates of growth, mortality, and sinking. Forecasts for north and south of Jamaica are evaluated with satellite-observed distributions, associated with beaching events in specific years of heavy inundation, 2015 and 2018-20. These seasonal forecasts are evaluated, on lead times of up to 180 days. Forecasts are subject to leading modes of tropical climate variability, in particular the Atlantic Meridional Mode (AMM). More accurate forecasts for a given year are obtained with ensemble members from hindcast years with a similar spring AMM-index. This is most clearly evident during negative AMM phases in spring of 2015 and 2018, when positive sea surface temperature anomalies and anomalously weak trade winds were established across the northern tropics. On this evidence, SARTRAC-EFS is potentially useful in providing early warning of high sargassum prevalence. Extended to sargassum drift off West Africa, extensive cloud cover limits availability of the satellite data needed for full application and evaluation of SARTRAC-EFS in this region, although experimental forecasts off the coast of Ghana are found highly sensitive to the windage that is associated with strong onshore winds during boreal summer. Alongside other forecast systems, SARTRAC-EFS is providing useful early warnings of sargassum inundation at seasonal timescale
Modeling future flows of the Volta River system: impacts of climate change and socio-economic changes
No full textAs the scientific consensus concerning global climate change has increased in recent decades, research on potential impacts of climate change on water resources has been given high importance. However in Sub-Saharan Africa, few studies have fully evaluated the potential implications of climate change to their water resource systems. The Volta River is one of the major rivers in Africa covering six riparian countries (mainly Ghana and Burkina Faso). It is a principal water source for approximately 24 million people in the region. The catchment is primarily agricultural providing food supplies to rural areas, demonstrating the classic water, food, energy nexus. In this study an Integrated Catchment Model (INCA) was applied to the whole Volta River system to simulate flow in the rivers and at the outlet of the artificial Lake Volta. High-resolution climate scenarios downscaled from three different Global Climate Models (CNRM-CM5, HadGEM2-ES and CanESM2), have been used to drive the INCA model and to assess changes in flow by 2050s and 2090s under the high climate forcing scenario RCP8.5. Results show that peak flows during the monsoon months could increase into the future. The duration of high flow could become longer compared to the recent condition. In addition, we considered three different socio-economic scenarios. As an example, under the combined impact from climate change from downscaling CNRM-CM5 and medium+ (high economic growth) socio-economic changes, the extreme high flows (Q5) of the Black Volta River are projected to increase 11% and 36% at 2050s and 2090s, respectively. Lake Volta outflow would increase +1% and +5% at 2050s and 2090s, respectively, under the same scenario. The effects of changing socio-economic conditions on flow are minor compared to the climate change impact. These results will provide valuable information assisting future water resource development and adaptive strategies in the Volta Basin.</p
The contribution of coastal land subsidence to potential sea-level rise impact in data-sparse settings: The case of Ghana’s Volta delta
Get PDFDeltas are highly valuable environmental systems, ensuring various livelihoods through their ecosystem services. However, human impact and climate change stressors are impacting deltas immensely. Consequently, many deltas, including Ghana's Volta Delta, are facing increasing risks, especially as hazards are increasing in magnitude and impacting coastal livelihoods. To provide a better understanding of coastal hazards in the Volta Delta, this study assessed the Delta's subsidence regime and its consequences for the potential impact of sea-level rise (SLR). Using the Interferometric Synthetic Aperture Radar (InSAR) technique and Global Navigation Satellite System (GNSS) surveys, vertical land motion (VLM) was documented. Interferograms of Sentinel-1 data from 2016 to 2020 indicated subsiding rates of up to −9.2 mm/yr. By combining local VLM information with recent SLR projections and elevation data, this study updates those projections and provides local assessments of potential Relative SLR (rSLR) impact. According to these locally improved scenarios, up to ∼45 % of the Delta will fall below local sea level by 2100, of which close to 10 % is explained by the integration of local VLM data alone. Depending on the climate change scenarios used, land subsidence will increase the deltaic area at risk by 4.31 % (96.27 km2) to 10.18 % (227.64 km2) and consequently exacerbate its exposure to coastal inundation. To avert the projections, the study recommends robust monitoring regimes; alternative freshwater sources to groundwater; reduced sediment trapping and river obstruction; and the need to stall ongoing oil and gas prospecting and subsequent extraction in the Voltain Basin
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