Population development as a driver of coastal risk: Current trends and future pathways

Abstract

Impact StatementCoastal risks will increase in the course of the 21 st century due to climate change, the future impacts of which will largely be driven by socioeconomic developments in coastal locations. Coastal zones have been attractive for human settlement for centuries, resulting in higher population growth in coastal compared to inland locations. Globally, these trends are expected to continue in the future, resulting in an increase in coastal exposure, the extent of which depends on changes in socioeconomic conditions that drive population growth and coastal migration processes. These processes have thus far not been accounted for in continental-to global-scale coastal risk assessments in a systematic manner. Beyond illustrating the need to mainstream the use of socioeconomic scenarios to explore future coastal exposure, this review highlights the importance to additionally account for aspects of vulnerability in assessing coastal risks, including socioeconomic characteristics of exposed populations (e.g., age, education levels, ethnicity), adaptation responses, and migration decisions. Furthermore, more systematic reporting of data and methods used in such assessments is necessary to enable comparison of the outcomes of various continental-to globalscale studies. By establishing hotspots of exposure and vulnerability, the results of such assessments can inform coastal policies and risk management strategies that are sustainable under a wide range of coastal futures.

Exploring spatial feedbacks between adaptation policies and internal migration patterns due to sea-level rise

“…15 , 16 , 34 , 37 ) are difficult to compare, also due to differences in the input data used 23 , 74 , 106 . Transparent reporting of scenario assumptions, modeling approaches, and input data is important to contextualize uncertainties in the modeling chain 27 , 74 . Quantifying these uncertainties systematically in a sensitivity analysis, by comparing migration modeling approaches or the effect of different input data (e.g., population, urban settlements, SLR projections, elevation) on model results is urgently needed in follow-up research.…”

“…In 2010, about 27% of the global population and 34% of the urban population lived in a coastal strip that covered 9% of the global land area 21 . These spatial patterns are expected to continue in the future due to progressing urbanization as well as the continued high attractiveness of coastal areas for human settlement 24 – 27 . Therefore, SLR may result in two types of internal migration responses: in permanent migration due to slow-onset impacts such as submergence of land or coastal erosion, and in temporary displacements during coastal flooding due to ESL 18 , 28 .…”

Comparative analysis of sandy beach and foredune geomorphic change measurements from Apple LiDAR and small-unoccupied aerial systems

“…Beach and foredune morphodynamics dictate the physical vulnerability of coastal areas to hazards, such as sea level rise and storms. As people continue to develop and populate low elevation coastal zones, which include sandy beaches and foredunes [42], hazard risk and exposure increases [43]. These coastal hazards could lead to costly environmental and socio-economic challenges, with an estimated US$1 trillion in potential economic impacts [44,45].…”

A Comprehensive Probabilistic Flood Assessment Accounting for Hydrograph Variability of ESL Events

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Flooding from extreme sea levels (ESLs) is one of the greatest threats that low-lying coastal areas are facing in the 21st century (Intergovernmental Panel on Climate Change [IPCC], 2022;Tebaldi et al, 2021). These areas are densely populated which exacerbates their exposure to flooding (Kummu et al, 2016;MacManus et al, 2021;Reimann et al, 2023). An estimated 148 million people and total assets worth $US7.76 trillion are currently exposed to a 1-in-100-year ESL event globally (Kirezci et al, 2020).

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