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Coral Islands Defying the Negative Consequences of Sea Level Rise

Paper Reviewed
Kench, P.S., Thompson, D., Ford, M.R., Ogawa, H. and McLean, R.F. 2015. Coral islands defy sea-level rise over the past century: Records from a central Pacific atoll. Geology 43: 515-518.

Introducing their study, Kench et al. (2015) write that "low-lying coral reef islands are coherent accumulations of sand and gravel deposited on coral reef surfaces that provide the only habitable land in atoll nations such as Kiribati, Tuvalu, and the Marshall Islands in the Pacific Ocean, and the Maldives in the Indian Ocean." And they say that in extreme cases, such as those that are predicted by the world's climate alarmists, "rising sea level is expected to erode island coastlines," forcing "remobilization of sediment reservoirs and promoting island destabilization," thereby making them "unable to support human habitation and rendering their populations among the first environmental refugees," citing Kahn et al. (2002) and Dickinson (2009). But will this ever really happen?

One phenomenon that suggests it could occur is the high rate of sea level rise (5.1 ± 0.7 mm/yr) and the consequent changes in shoreline position that have occurred over the past 118 years at 29 islands of Funafuti Atoll in the tropical Pacific Ocean. However, Kench et al. say that "despite the magnitude of this rise, no islands have been lost," noting, in fact, that "the majority have enlarged, and there has been a 7.3% increase in net island area over the past century (AD 1897-2013)." And they add that "there is no evidence of heightened erosion over the past half-century as sea-level rise accelerated," noting that "reef islands in Funafuti continually adjust their size, shape, and position in response to variations in boundary conditions, including storms, sediment supply, as well as sea level."

The final conclusion of the four New Zealand scientists and their Australian collaborator was thus that "islands can persist on reefs under rates of sea-level rise on the order of 5 mm/year," which is a far greater rate-of-rise than what has been observed over the past half-century of significant atmospheric CO2 enrichment.

References
Dickinson, W.R. 2009. Pacific atoll living: How long already and until when? GSA Today 19: 10.1130/GSATG35A.1.

Khan, T.M.A., Quadir, D.A., Murty, T.S., Kabir, A., Aktar, F. and Sarker, M.A. 2002. Relative sea level changes in Maldives and vulnerability of land due to abnormal coastal inundation. Marine Geodesy 25: 133-143.

Posted 24 November 2015