269 research outputs found
Physical drivers of pelagic sargassum bloom interannual variability in the Central West Atlantic over 2010–2020
No full textSince 2011, unprecedented pelagic sargassum seaweed blooms have occurred across the tropical North Atlantic, with severe socioeconomic impacts for coastal populations. To investigate the role of physical drivers in post-2010 sargassum blooms in the Central West Atlantic (CWA), conditions are examined across the wider tropical North Atlantic, using ocean and atmospheric re-analyses and satellite-derived datasets. Of particular consequence for the growth and drift of sargassum are patterns and seasonality of winds and currents. Results suggest that in years of exceptionally large sargassum blooms (2015, 2018), the Intertropical Convergence Zone (ITCZ), an area of maximum wind convergence where sargassum naturally accumulates, shifted southward, towards nutrient-rich waters of the Amazon River plume and the equatorial upwelling zone further stimulating sargassum growth. These changes are associated with modes of natural variability in the tropical Atlantic, notably a negative phase of the Atlantic Meridional Mode (AMM) in 2015 and 2018, and a positive phase of the Atlantic Niño in 2018. Negative AMM in these 2 years is also associated with stronger trade winds and enhanced northwest Africa upwelling, probably resulting in stronger southwestward nutrient transport into the eastern part of CWA. Moreover, in contrast with most years, important secondary winter blooms took place in both 2015 and 2018 in the northern part of CWA, associated with excessive wind-driven equatorial upwelling and anomalously strong northwestward nutrient transport.</p
A biophysical and socioeconomic review of the Volta Delta, Ghana
No full textDelta regions are dynamic and rich environments with diverse economic activities and are often densely populated.Deltas are being shaped by multiple drivers, including changes in sediment delivery to the coastal zone due to catchment changes, especially construction of dams on major rivers, intensified agriculture and/or aquaculture, mining, urbanisation, human-induced subsidence, climate change, and sea-level rise. These environmental challenges have significant implications for the livelihoods of delta residents. Thus, the integrated assessment of deltas is now attracting the attention of the scientific research community to analyse and understand deltas as coupled biophysical and socioeconomic systems. Most attention has been focussed on the major deltas. This review focusses on the smaller but regionally significant Volta delta, Ghana. Previous scientific studies are limited, with more focus upstream on the Volta River basin. Many contemporary problems are recognised in the Volta delta, especially erosion and flooding of the open coast fringe, such as at the town of Keta. However, these problems are treated independently, which may hinder identifying the root causes and the most effective solutions. Equally, the emergence of new problems might be anticipated and hence better managed or even avoided. This paper reviews the present delta with emphasis on biophysical processes and socioeconomic characteristics and considers in particular the current drivers and challenges.With this information, a research agenda will be established for a more systemic approach to understanding the Volta delta, including its residents and development
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
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
Science and policy lessons learned from a decade of adaptation to the emergent risk of sargassum proliferation across the tropical Atlantic
No full textClimatic and anthropogenic changes appear to be driving the emergence of new ecosystem and human health risks. As new risks emerge, and the severity or frequency of known risks change, we ask: what evidence is there of past adaptations to emergent risks? What scientific and policy processes lead to adaptive solutions that minimise the impacts of these events, and draw out opportunities? We identify science and policy lessons learned from coping with, and responding to, the sudden arrival of brown macroalgae (pelagic sargassum) that has proliferated across the tropical Atlantic since 2011. Drawing on an evidence base developed from a systematic search of literature relating to sargassum seaweed, and using event timelines and word clouds, we provide an analysis of lessons learned from a case study of adaptive responses across three continents to an emergent risk over the course of a decade. We reflect on successes and failures as well as opportunities taken in building adaptive capacity to address the risk in four key domains: policy, knowledge and evidence, monitoring and early warning, and technology and valorisation. Failures include: lack of environmental risk registries; missed opportunities to share monitoring data; and lack of a shared approach to manage the risk. Successes include: development of national management strategies; open-access knowledge hubs, networks and webinars sharing information and best practice; semi-operational early advisory systems using open access remote sensing data; numerous innovations customising clean-up and harvesting equipment, and research and development of new uses and value-added products
Sargassum Biomass Movement and Proliferation in the Eastern Tropical Atlantic
No full textSince 2011, pelagic sargassum blooms (S. fluitans and S. natans) have impacted coastal communities, aquaculture, tourism, and biodiversity across the Tropical Atlantic region. Whilst the initial event is generally attributed to an anomalous North Atlantic Oscillation (2009–2010), the drivers of sargassum movement and proliferation remain unclear. This research gap is particularly evident in West Africa, where annual and seasonal sargassum variability is under-researched, and a lack of consensus exists on seasonal and annual trends. This paper addresses these gaps by (1) providing a first attempt at characterising the seasonal and annual trends of sargassum biomass in the Eastern Tropical Atlantic, through using satellite imagery to create a time-series for 2011–2022; and (2) exploring the hypothetical drivers of movement and proliferation of sargassum for this area, through assessing its co-variation with potential drivers including atmospheric, oceanic, and policy, establishing a historical timeline of events. The time-series analysis reveals an annual biomass peak in September and a second peak between March and May. The exploration of potential drivers reveals that alongside sea surface temperature there are multiple factors that could be influencing sargassum biomass, and that further research is necessary to clarify primary and secondary drivers. The results contribute to understanding drivers, impacts, and predictions of sargassum blooms in the Eastern Tropical Atlantic. We anticipate that our findings will enable sargassum-affected areas to better anticipate the size and timing of sargassum events in West Africa and offer researchers a new perspective on possible drivers of proliferation within the wider Tropical Atlantic region
What are the implications of sea-level rise for a 1.5°C, 2°C and 3°C rise in global mean temperatures in the Ganges-Brahmaputra-Meghna and other vulnerable deltas?
No full textEven if climate change mitigation is successful, sea levels will keep rising. With subsidence, relative sea-level rise represents a long-term threat to low-lying deltas. A large part of coastal Bangladesh was analysed using the Delta Dynamic Integrated Emulator Model to determine changes in flood depth, area and population affected given sea-level rise equivalent to global mean temperature rises of 1.5°C, 2.0°C and 3.0°C with respect to pre-industrial for three ensemble members of a modified A1B scenario. Annual climate variability today (with approximately 1.0°C of warming) is potentially more important, in terms of coastal impacts, than an additional 0.5°C warming. In coastal Bangladesh, the average depth of flooding in protected areas is projected to double to between 0.07m to 0.09m when temperatures are projected at 3.0°C compared with 1.5°C. In unprotected areas, depth of flooding is projected to increase by approximately 50% to 0.21-0.27m, whilst the average area inundated increases 2.5 times (from 5% to 13% of the region) in the same temperature frame. The greatest area of land flooded is projected in the central and north-east regions. In contrast, lower flood depths, less land area flooded and fewer people are projected in the poldered west of the region. Over multi-centennial timescales, climate change mitigation and controlled sedimentation to maintain relative delta height are key to a delta’s survival. With slow rates of sea-level rise, adaptation remains possible, but further support is required. Monitoring of sea-level rise and subsidence in deltas is recommended, together with improved data sets of elevation. <br/
An Evaluative Study of a Distance Teacher Education Program in a University in Ghana
No full textThe study used an adaptation of Provus’ discrepancy evaluation model to evaluate a distance teacher education program in the University of Cape Coast, the premier teacher education institution in Ghana. The study involved comparing performance data of the program as perceived by students and faculty/administrators to standards prepared from the program’s design. Performance data was obtained by administering two survey instruments to a random sample of students and faculty/administrators. Discrepancies between performance and standards were reported. The study concluded that although there were some discrepancies between program standards and performance the program is fulfilling its purpose of upgrading the professional and academic performance of a large number of teachers in the public K-8 schools in Ghana
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