Coastal flood damage and adaptation costs under 21st century sea-level rise

Abstract

Coastal flood damage and adaptation costs under 21st century sea-level rise are assessed on a global scale taking into account a wide range of uncertainties in continental topography data, population data, protection strategies, socioeconomic development and sea-level rise. Uncertainty in global mean and regional sea level was derived from four different climate models from the Coupled Model Intercomparison Project Phase 5, each combined with three land-ice scenarios based on the published range of contributions from ice sheets and glaciers. Without adaptation, 0.2-4.6% of global population is expected to be flooded annually in 2100 under 25-123 cm of global mean sea-level rise, with expected annual losses of 0.3-9.3% of global gross domestic product. Damages of this magnitude are very unlikely to be tolerated by society and adaptation will be widespread. The global costs of protecting the coast with dikes are significant with annual investment and maintenance costs of US$ 12-71 billion in 2100, but much smaller than the global cost of avoided damages even without accounting for indirect costs of damage to regional production supply. Flood damages by the end of this century are much more sensitive to the applied protection strategy than to variations in climate and socioeconomic scenarios as well as in physical data sources (topography and climate model). Our results emphasize the central role of long-term coastal adaptation strategies. These should also take into account that protecting large parts of the developed coast increases the risk of catastrophic consequences in the case of defense failure. coastal flooding | climate change impact | loss and damage A lthough increased coastal flood damage and corresponding adaptation may be one of the most costly aspects of climate change (1), few studies have assessed this impact globally. The first of these studies considered flood risk to people under a 1-m sea-level rise and adaptation via dikes, but without socioeconomic change (2). Follow-up studies refined this analysis in several directions: (i) adding a range of sea-level scenarios and a single socioeconomic scenario (3, 4), (ii) applying a range of socioeconomic scenarios (5), (iii) extending the resolution of the coastal zone to subnational levels (6, 7), and (iv) including regional patterns of climate-induced sea-level rise (6). These studies further differ in the digital elevation model (DEM) and spatial population datasets used, as well as the adaptation strategies applied. No study has, however, explored all of these dimensions together.This paper addresses this gap and assesses the impacts of increased coastal flooding on population and assets by comparing results attained using various available data sources and adaptation strategies under a comprehensive sample of state-of-theart socioeconomic and sea-level rise scenarios. Flood risk is considered in terms of expected annual damage to assets, expected annual number of people flooded, and adaptation costs in terms of dike investment and additional main...

Debates—Perspectives on socio‐hydrology: Capturing feedbacks between physical and social processes

“…To show an example of the implementation of the novel approach, we use this model to explore the impact of increasing frequency and magnitude of flood levels (Figure 5a), which can be plausibly caused by climate change or sea level rise [e.g., Hinkel et al, 2014;Jongman et al, 2014]. To this end, we simulate the behavior of the aforementioned prototypes of risk management systems: green societies and technological societies.…”

“…This trend looks set to worsen in the near future, as rapid urbanization continues to swell the size of the population living on floodplains above the current size of one billion, while flood levels might increase due to climate change and sea level rise [Hinkel et al, 2014;Jongman et al, 2014].…”

Improving Flood Prediction Assimilating Uncertain Crowdsourced Data into Hydrological and Hydraulic Models

“…Flood events in Europe, such as the 2002 Elbe floods and the 2007 UK floods, are considered national crises and are estimated to have caused around 15 and 6.5 billion Euro of damage respectively (European Environment Agency, 2006). Moreover, due to the combined effects of rapid urbanization, growth of population near to floodplains and flood levels increasing due to climate change and sea level rise, this trend seems likely to worsen in the near future (Hinkel et al, 2014;Jongman et al, 2014). In fact, societies seem to have the tendency to settle near water courses and this can be demonstrated by the fact that, according to the United Nations (2012), nine of the 10 largest urban 1.…”

Managing coastal environments under climate change: Pathways to adaptation

“…A high-end scenario is preferred as a baseline because it is both plausible and conservative. Bereft of cheap energy and natural resources, the costs of adaptation and mitigation will increase throughout time and the transition towards a lowcarbon society will be difficult (Brown et al, 2013;Hinkel et al, 2014). Available resources may be allocated to further economic growth (with the possibility of reaching a dead-end at the short-term) or to a societal transition combining rigid and flexible elements.…”