An assessment of the physical impacts of sea-level rise and coastal adaptation: a case study of the eastern coast of Ghana

Sea-level rise is a major coastal issue in the 21st century because many of the world??s built assets are located in the coastal zone. Coastal erosion and flooding are serious threats along the coast of Ghana, particularly, the eastern coast where the Volta delta is located. Past human interventions, climate change and the resultant rise in sea-levels, increased storm intensity and torrential rainfall have been blamed for these problems. Accelerated sea-level rise and storm surge pose serious threat to coastal habitat, bio-diversity and socio-economic activities in the coastal zone of Ghana and elsewhere. There is the need for an holistic assessment of the impacts of sea-level rise on the coast zone in order to formulate appropriate adaptation policies and strategies to mitigate the possible effects. Using the eastern coast of Ghana as a case study, this paper assesses the physical impacts of accelerated sea level rise and storm surge on the coastal environment. It evaluates adaptation policies and plans that could be implemented to accommodate the present and any future impacts. Field investigation and Geographic Information System (GIS) are among the methods used for the assessment. The outcome of the assessment has provided comprehensive knowledge of the potential impacts of accelerated sea-level rise and storm surge on the eastern coast. It has facilitated identification of management units, the appraisal of alternate adaptation policies and the selection of the best policy options based upon the local conditions and environmental sustainability. Among other things, this paper reveals that the eastern coast of Ghana is highly vulnerable to accelerated sea-level rise and therefore, requires sustainable adaptation policies and plans to manage the potential impacts. It recommends that various accommodation policies, which enable areas to be occupied for longer before eventual retreat, could be adapted to accommodate vulnerable settlements in the eastern coast of Ghana.     

Integrating knowledge to assess coastal vulnerability to sea-level rise: The development of the DIVA tool

This paper describes the development of the DIVA tool, a user-friendly tool for assessing coastal vulnerability from subnational to global levels. The development involved the two major challenges of integrating knowledge in the form of data, scenarios and models from various natural, social and engineering science disciplines and making this integrated knowledge accessible to a broad community of end-users. These challenges were addressed by (i) creating and applying the DIVA method, an iterative, modular method for developing integrating models amongst distributed partners and (ii) making the data, scenarios and integrated model, equipped with a powerful graphical user interface, directly and freely available to end-users.     

Spatial variations of sea-level rise and impacts: An application of DIVA

Due to complexities of creating sea-level rise scenarios, impacts of climate-induced sea-level rise are often produced from a limited number of models assuming a global uniform rise in sea level. A greater number of models, including those with a pattern reflecting regional variations would help to assure reliability and a range of projections, indicating where models agree and disagree. This paper determines how nine new patterned-scaled sea-level rise scenarios (plus the uniform and patterned ensemble mean rises) influence global and regional coastal impacts (wetland loss, dry land loss due to erosion and the expected number of people flooded per year by extreme sea levels). The DIVA coastal impacts model was used under an A1B scenario, and assumed defences were not upgraded as conditions evolved. For seven out of nine climate models, impacts occurred at a proportional rate to global sea-level rise. For the remaining two models, higher than average rise in sea level was projected in northern latitudes or around populated coasts thus skewing global impact projections compared with the ensemble global mean. Regional variability in impacts were compared using the ensemble mean uniform and patterned scenarios: The largest relative difference in impacts occurred around the Mediterranean coast, and the largest absolute differences around low-lying populated coasts, such as south, south-east and east Asia. Uniform projections of sea-level rise impacts remain a useful method to determine global impacts, but improved regional scale models of sea-level rise, particularly around semi-enclosed seas and densely populated low-lying coasts will provide improved regional impact projections and a characterisation of their uncertainties.     

The economic cost of greenhouse-induced sea-level rise for developed property in the United States

Estimates of the true economic cost that might be attributed to greenhouse-induced sea-level rise on the developed coastline of the United States are offered for the range of trajectories that is now thought to be most likely. Along a 50-cm sea level rise trajectory (through 2100), for example, transient costs in 2065 (a year frequently anticipated for doubling of greenhouse-gas concentrations) are estimated to be roughly $70 million (undiscounted, but measured in constant 1990$). More generally and carefully cast in the appropriate context of protection decisions for developed property, the results reported here are nearly an order of magnitude lower than estimates published prior to 1994. They are based upon a calculus that reflects rising values for coastal property as the future unfolds, but also includes the cost-reducing potential of natural, market-based adaptation in anticipation of the threat of rising seas and/or the efficiency of discrete decisions to protect or not to protect small tracts of property that will be made when necessary and on the (then current) basis of their individual economic merit.This research was funded by the Electric Power Research Institute as part of its impacts assessment program. Notwithstanding that support, the opinions expressed here and responsibility for any errors reside with the authors. The authors express their appreciation for comments offered on earlier drafts by Rick Freeman, Rob Mendelsohn, Joel Smith, Tom Wilson, Jim Titus, Robert Chen and the Snowmass Workshop on the Impacts of Global Change. If we may, we would also like to dedicate this paper to the memory of Dr. James Broadus from the Woods Hole Oceanographic Institution. His untimely death was, indeed, tragic; and we miss both his company and his flawless contribution to this and other work.     

The economic impact of extreme sea-level rise: Ice sheet vulnerability and the social cost of carbon dioxide

The possibility of extreme sea-level rise is one of the commonly cited reasons for concern about climate change. Major increases in sea level would likely be driven by the melting or collapse of major ice sheets. This possibility has implications for the social cost of carbon dioxide, which is a key policy value as well as a useful summary measure of damage caused by greenhouse gas emissions.This paper extends earlier work on the importance of low-probability, high-impact events for the social cost of carbon dioxide to incorporate the possibility of extreme sea-level rise.To estimate its impact, an integrated assessment model is used, which allows a probabilistic assessment of climate change damages based on the linkages between the economic and climate systems. In the model, the generic discontinuity damage is replaced with the possibility of large-scale damage from factors that are taken to be correlated with temperature rise and, crucially for this paper, explicit consideration of extreme sea-level rise.Estimates of the amount of increase in the social cost of carbon dioxide that can be expected from incorporating extreme sea-level rise show that the increase is significant, though not especially large in percentage terms.The paper contributes to the literature of how to represent uncertain climate impacts in integrated assessment models and the associated estimation of the social cost of carbon dioxide.     

An economic approach to adaptation: illustrations from Europe

Policy makers are still struggling to find a rational and effective way to handle adaptation to climate change. This paper discusses a more strategic, economic approach to public adaptation and compares it with adaptation practice in Europe. An economic approach to adaptation involves setting priorities, both spatially (where to adapt) and inter-temporally (when to adapt). The paper reviews what we know about Europe’s geographic adaptation priorities. On inter-temporal priorities, it recommends fast-tracking two types of action: Win-win measures that yield an immediate return, such as water efficiency, and strategic decisions on infrastructure and spatial planning that have long-term consequences for Europe’s vulnerability profile. An economic approach to adaptation involves careful project design to ensure adaptation measures are cost-effective and flexible in the light of climate uncertainty (how to adapt). The final element of an economic approach to adaptation is the division of labour between the state and private actors (who should adapt). The paper argues that the traditional functions of the state—the provision of public goods, creation of an enabling environment and protection of the vulnerable—also apply to adaptation.     

Implications of sea-level rise and extreme events around Europe: a review of coastal energy infrastructure

Sea-level rise and extreme events have the potential to significantly impact coastal energy infrastructure through flooding and erosion. Disruptions to supply, transportation and storage of energy have global ramifications and potential contamination of the natural environment. On a European scale, there is limited information about energy facilities and their strategic plans for adapting to climate change. Using a Geographical Information System this paper assesses coastal energy infrastructure, comprising (1) oil/gas/LNG/tanker terminals and (2) nuclear power stations. It discusses planning and adaptation for sea-level rise and extreme events. Results indicate 158 major oil/gas/LNG/tanker terminals in the European coastal zone, with 40 % located on the North Sea coast. There are 71 operating nuclear reactors on the coast (37 % of the total of European coastal countries), with further locations planned in the Black, Mediterranean and Baltic Seas. The UK has three times more coastal energy facilities than any other country. Many north-west European countries who have a high reliance on coastal energy infrastructure have a high awareness of sea-level rise and plan for future change. With long design lives of energy facilities, anticipating short, medium and long-term environmental and climatic change is crucial in the design, future monitoring and maintenance of facilities. Adaptation of coastal infrastructure is of international importance, so will be an ongoing important issue throughout the 21^st century.     

Impact assessments and policy responses to sea-level rise in three US states: An exploration of human-dimension uncertainties

Uncertainties in the human dimensions of global change deeply affect the assessment and responses to climate change impacts such as sea-level rise (SLR). This paper explores the uncertainties in the assessment process and in state-level policy and management responses of three US states to SLR. The findings reveal important political, economic, managerial, and social factors that enable or constrain SLR responses; question disasters as policy windows; and uncover new policy opportunities in the history of state coastal policies. Results suggest that a more realistic, and maybe more useful picture of climate change impacts will emerge if assessments take more seriously the locally embedded realities and constraints that affect individual decision-makers’ and communal responses to climate change.     

Local values for fairer adaptation to sea-level rise: A typology of residents and their lived values in Lakes Entrance,Australia

Understanding the values and socio-economic characteristics of people at risk from climate change will inform how people feel about the likely distribution of impacts, as well as adaptation responses. This knowledge is necessary if adaptation is to achieve distributive fairness now and into the future. This study advances methods and analyses used in values-based adaptation research by using segmentation to explain the diversity of values that exist within a community, and on this basis identify particular groups at risk. A telephone survey was conducted with residents of Lakes Entrance, Australia—a coastal community already adapting to projected sea-level rise. The purpose was to determine the priorities residents place on a range of lived values—valuations that individuals make about what is important in their lives and the places they live. The telephone survey data was then analysed using cluster analysis to develop a lived values typology of residents. The analysis revealed that there are at least eight types of residents living in Lakes Entrance and that each group of residents has a unique set of lived values that will be differentially affected by sea-level rise and adaptation. The findings indicate that if sea-level rise adaptation policy is to be distributively fair it needs to develop a suite of adaptation responses that ensure that the lived values of each group of residents, and thus a diversity of values, are maintained or enhanced.     

Economic impacts of climate change in Europe: sea-level rise

This paper uses two models to examine the direct and indirect costs of sea-level rise for Europe for a range of sea-level rise scenarios for the 2020s and 2080s: (1) the DIVA model to estimate the physical impacts of sea-level rise and the direct economic cost, including adaptation, and (2) the GTAP-EF model to assess the indirect economic implications. Without adaptation, impacts are quite significant with a large land loss and increase in the incidence of coastal flooding. By the end of the century Malta has the largest relative land loss at 12% of its total surface area, followed by Greece at 3.5% land loss. Economic losses are however larger in Poland and Germany (483 and483 and 391 million, respectively). Coastal protection is very effective in reducing these impacts and optimally undertaken leads to protection levels that are higher than 85% in the majority of European states. While the direct economic impact of sea-level rise is always negative, the final impact on countries’ economic performances estimated with the GTAP-EF model may be positive or negative. This is because factor substitution, international trade, and changes in investment patterns interact with possible positive implications. The policy insights are (1) while sea-level rise has negative and huge direct economic effects, overall effects on GDP are quite small (max −0.046% in Poland); (2) the impact of sea-level rise is not confined to the coastal zone and sea-level rise indirectly affects landlocked countries as well (Austria for instance loses −0.003% of its GDP); and (3) adaptation is crucial to keep the negative impacts of sea-level rise at an acceptable level.     

Exposure of developing countries to sea-level rise and storm surges

An increase in sea surface temperature is strongly evident at all latitudes and in all oceans. The scientific evidence to date suggests that increased sea surface temperature will intensify cyclone activity and heighten storm surges. The paper assesses the exposure of (coastal) developing countries to sea-level rise and the intensification of storm surges. Geographic Information System (GIS) software is used to overlay the best available, spatially-disaggregated global data on critical exposed elements (land, population, GDP, agricultural extent and wetlands) with the inundation zones projected with heightened storm surges and a 1 m sea-level rise. Country-level results indicate a significant increase in exposure of developing countries to these climate-induced changes.     

Island abandonment and sea-level rise: An historical analog from the Chesapeake Bay,USA

Small islands are widely agreed to be vulnerable to human-induced sea-level rise during the 21st century and beyond, with forced abandonment of some low-lying oceanic islands being a real possibility. A regional abandonment of islands in the Chesapeake Bay, USA provides an historical analog of such vulnerability as this has been linked to a mid 19th Century acceleration in relative sea-level rise. Using a case study approach for Holland Island, Maryland, this hypothesis was tested using a range of physical and human historical data. While sea-level rise was the underlying driver, this analysis shows that the abandonment was more complex than a direct response to sea-level rise. Between 1850 and 1900, Holland Island was a booming community and population increased from 37 to 253, with immigration causing the majority of the increase. At the same time, the upland area where people made their homes was steadily diminishing, losing about 15 ha or 38% of the total. After 1900, the island experienced a decrease in population to 169 in 1916, with final abandonment in 1918, with the exception of one family who left by 1920. Final abandonment was triggered by this depopulation as the population fell below a level that could support critical community services, and the community lost faith in their future on Holland Island. It is likely that similar social processes determined the abandonment of the other Chesapeake Bay islands. Looking to the future, it shows that many small low-lying islands could be abandoned due to sea-level rise long before they become physically uninhabitable.     

Plausible responses to the threat of rapid sea-level rise in the Thames Estuary

This paper considers the perceptions and responses of selected stakeholders to a very low probability but high consequence climatic ‘surprise’—a scenario of rapid collapse of the West Antarctic ice sheet, producing a global rise in sea-level of 5  m over 100 years. It uses a case study of the Thames Estuary, UK, including London. Through a process of dialogue involving one-to-one interviews and a 1-day policy exercise, we addressed influences on decision-making when information is uncertain and our ability to plan, prepare for and implement effective ways of coping with this extreme scenario. The interviews and policy exercise explored plausible responses to the scenario and identified weaknesses in flood management approaches to dealing with such an occurrence. The analysis shows that an extreme scenario could be highly challenging, even for an area with well-developed institutions. Participants favoured two options (a) reconfiguring London around the rising water, and (b) building a new downstream barrier which would allow London to continue as today. The lack of consensus suggests the potential for policy paralysis in response to what is a highly uncertain phenomena—this could lead to a forced, unplanned response as the rapid change overwhelmed the existing defence capability. Hence, low probability, high consequence climatic events may challenge our existing institutions. Adaptive management is presented as an approach which could address this challenge.