Many Atolls May be Uninhabitable Within Decades Due to Climate Change.

Curt D Storlazzi,Paul Berkowitz,Edwin P.L Elias

doi:10.1038/srep14546

Curt D Storlazzi, Paul Berkowitz + Show 1 more

Open Access

https://doi.org/10.1038/srep14546

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Abstract

Observations show global sea level is rising due to climate change, with the highest rates in the tropical Pacific Ocean where many of the world’s low-lying atolls are located. Sea-level rise is particularly critical for low-lying carbonate reef-lined atoll islands; these islands have limited land and water available for human habitation, water and food sources, and ecosystems that are vulnerable to inundation from sea-level rise. Here we demonstrate that sea-level rise will result in larger waves and higher wave-driven water levels along atoll islands’ shorelines than at present. Numerical model results reveal waves will synergistically interact with sea-level rise, causing twice as much land forecast to be flooded for a given value of sea-level rise than currently predicted by current models that do not take wave-driven water levels into account. Atolls with islands close to the shallow reef crest are more likely to be subjected to greater wave-induced run-up and flooding due to sea-level rise than those with deeper reef crests farther from the islands’ shorelines. It appears that many atoll islands will be flooded annually, salinizing the limited freshwater resources and thus likely forcing inhabitants to abandon their islands in decades, not centuries, as previously thought.

Highlights

Sea-level rise will exacerbate the impacts of storm waves on atolls’ coral reefs by reducing wave breaking at the reef crest and increasing the water depth relative to the hydrodynamic roughness over the reef flat
As shown previously[17], it is apparent that the passive “bathtub” modeling predicts less inundation than the dynamic flood modeling for these low-lying atoll islands
More of the atoll islands will be periodically inundated at a given future sea level when taking wave-driven processes into account than predicted by the passive models

Summary

Introduction

Sea-level rise will exacerbate the impacts of storm waves on atolls’ coral reefs by reducing wave breaking at the reef crest and increasing the water depth relative to the hydrodynamic roughness over the reef flat. By reducing incident wave energy dissipation, sea-level rise will cause larger waves to impact the coastline[12]. These larger waves will increase the resulting wave-driven set-up[11] and water levels at the shoreline. This study builds on preliminary efforts[17] to explore the combined effect of sea-level rise inundation and storm-induced wave-driven flooding on atoll islands within the Northwestern Hawaiian Islands that are the home to many threatened and endangered endemic species[15] and have high-resolution topographic and bathymetric data, yet this approach is applicable to most populated atolls around the world

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Conclusion