An assessment of whether long-term global changes in waves and storm surges have impacted global coastlines

Abstract

A common inference in research studies of observed and projected changes in global ocean wave height and storm surge, is that such changes are potentially important for long-term coastal management. Despite numerous studies of the impacts of anthropogenic climate change on trends in global wind and waves, a clear link to impacts on sandy coastlines, at global scale, is yet to be demonstrated. This study presents a first-pass assessment of the potential link between historical trends in global wave and storm surge values and recession/progradation rates of sandy coastlines since the 1980s. Global datasets of waves, surge and shoreline change rate are used for this purpose. Over the past 30 + years, we show that there have been clear changes in waves and storm surge at global scale. The data, however, does not show an unequivocal linkage between trends in wave and storm surge climate and sandy shoreline recession/progradation. We conclude that these long-term changes in oceanographic parameters may still be too small to have a measurable impact on shoreline recession/progradation and that primary drivers such as ambient imbalances in the coastal sediment budget may be masking any such linkages.

Coastal Morphodynamics and Climate Change: A Review of Recent Advances

“…From a notable recent analysis of a 50-year time series of monthly beach surveys of a high-energy beach system on Australia's New South Wales Coast [53], it was concluded that while there has been no long-term net coastal recession, beach fluctuations that occur reflect patterns of storminess and the capacity of the beach to recover in post-storm periods. Consistent with these Australian studies, a recent analysis of global trends in changing wave intensity and related shoreline behavior [54] reports that "Over the past 30 + years, we show that there have been clear changes in waves and storm surge at global scale. The data, however, does not show an unequivocal linkage between trends in wave and storm surge climate and sandy shoreline recession/progression."…”

Role of Atmospheric Indices in Describing Shoreline Variability Along the Atlantic Coast of Europe

“…Global studies of shoreline change based on satellite‐derived shorelines (SDS) are becoming increasingly common (Almar et al., 2023; Ghanavati et al., 2023; Luijendijk et al., 2018; Mentaschi et al., 2018; Vousdoukas et al., 2020); however, concerns have been raised regarding satellite‐derived global applications (Cooper et al., 2020; Zăinescu et al., 2023). To explore links between shoreline response and modes of climate variability, robust methodologies for deriving shorelines involving wave and/or tide corrections (Castelle et al., 2021; Vos et al., 2023) or time‐ and spatial‐averaging techniques (Castelle et al., 2022; Warrick et al., 2023) must be applied.…”

“…On these short-to-medium time scales, wave variability is the main driver for shoreline change and beaches respond to individual storms (Harley et al, 2017), storm clusters (Dissanayake et al, 2015, seasonal variation in wave conditions (Masselink & Pattiaratchi, 2001) and inter-annual to decadal changes in wave forcing (Castelle et al, 2018). Shorelines are also expected to change over long-term (>25 years) time scales, for example, due to sea-level rise, but it has been challenging to identify and isolate the modest and longer-term shoreline trends from the much more dynamic and short-to-medium term changes imposed by wave climate variability (Ghanavati et al, 2023). Both wave-driven cross-shore and longshore sediment transport processes are responsible for changes in beach morphology and shoreline position, with cross-shore processes generally dominating seasonal and annual coastal change, whereas longshore processes tend to dominate the coastal response over decadal times (Vitousek et al, 2017).Temporal changes in wave forcing are controlled by large-scale weather patterns and their variability.…”

Global tropical cyclone extreme wave height climatology

“…In tropical and sub-tropical regions, tropical cyclones (or hurricanes or typhoons) represent the most extreme meteorological forcing events, generating wind speeds in excess of 50 m/s 1 – 4 and ocean significant wave heights in excess of 12 m 5 , 6 . As such, tropical cyclones have important societal impacts, resulting in damage to coastal infrastructure 7 , coastal flooding 8 and beach erosion 9 . Compared to higher latitude storms (extra-tropical cyclones), tropical cyclones are characterized by a relatively small well-formed core with an eye of typical radius from 10 to 40 km 2 , 10 , 11 and an asymmetric vortex wind field.…”