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Sea Level Rise in South Pacific Atolls

Posted on February 5, 2010

Late last year, Dr. Arthur Webb of the Pacific Island Applied Geoscience Commission made a presentation on Atoll shoreline response to sea level rise over the last 50 years – Pingelap & Mokil Atolls, FSM (Federated States of Mictronesia).

Copies of the 75 megabyte Powerpoint presentation can be downloaded at

The somewhat surprising conclusions of this analysis of the historic record were (adapted and emphasis added):

• There is a poor understanding of the relationship between sea-level rise and shoreline response in our South Pacific region but Bruun (1963) does not appear appropriate in the case of Pacific Atoll coasts.

• Despite the rates of sea-level rise thus-far experienced, the atoll shores so far studied tell a story of considerable stability and the majority have net trends of accretion or growth at this time

• The broad assumptions regarding widespread erosion due to sea level rise are for the coastal manager unhelpful and may divert attention from appropriate management responses and with regards to Climate Change, risks mal-adaptation.

• Stress such as possible changes in wave climate, storm frequency, reef productivity / structure (bleaching, acidification, energy window) may ultimately be more important drivers of climate change related impacts on tropical “coral” coasts than sea level rise.

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This presentation is a valuable demonstration of the dangers inherent in the small islands’ over-reliance on sea-level rise as the overwhelmingly important consequence of climate change . . . for myself, in the Caribbean I think the issues are much more related to the inability to recover vital ecosystem services from already compromised coastal and near shore ecoregions, especially if the rising sea levels simply result in new shorelines that are hardened by anthropogenic structures such as roads, sea walls, buildings and other structures.


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