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Rising tides: islands lost to the sea

Micronesia (above), the Solomon Islands and other low-lying Pacific areas are all at risk from rising sea levels, but understanding to what varying degrees is going to be vital to their long-term futures Micronesia (above), the Solomon Islands and other low-lying Pacific areas are all at risk from rising sea levels, but understanding to what varying degrees is going to be vital to their long-term futures Photosounds
07 Nov
2017
Numerous low-lying Pacific islands have disappeared under rising seas

At first it was anecdotal evidence. Locals from Pohnpei, an island in the Federated States of Micronesia, told researchers about two islands – Nahlapenlohd and Kepidau en Pehleng – that had disappeared beneath the waves in living memory. Taking to the skies, Patrick Nunn, a climatologist from the University of the Sunshine Coast in Queensland, revealed that another six uninhabited islands have been submerged since 2007.

The findings are part of a worrying trend emerging from Pacific island nations. Last year, satellite imagery of the Solomon Islands showed that five of its reef islands had vanished since the mid-20th century. While none of those were inhabited, a further six had lost large portions of land, forcing the relocation of two villages.

‘At least 11 islands across the northern Solomon Islands have either totally disappeared over recent decades, or are currently experiencing severe erosion,’ says Simon Albert, a senior research fellow at the University of Queensland.

Both aerial surveys suggest that the low-lying islands in Micronesia and the Solomon Islands are providing a glimpse into the future for low-lying Pacific regions, which experience seven to 12 millimetres of sea level rise per year – well above the global average of three millimetres.

However, Albert stresses that the island losses are not solely being caused by climate change – wave energy and climatic cycles are playing a role too. Specifically, trade winds spurred by the Pacific Decadal Oscillation, a long-lived El Nino-like pattern of climate variability, are helping to push up sea levels, while increasing wave energy is making some islands more at-risk than others. ‘Twelve of the islands studied in the Solomons demonstrated little noticeable change in shorelines, despite being subject to the same sea-level rise,’ he explains. Islands exposed to higher wave energy fared much worse.

Similarly, Nunn observed that the inhabited Micronesian island of Pohnpei showed ‘fewer effects than might be expected from recent sea level rise’, most likely because it is protected from waves by a fringe of mangrove forests.

Nunn believes that further understanding of specific conditions such as mangroves, sediment dynamics and wave energy will be an essential part of island resilience in the decades to come

This was published in the November 2017 edition of Geographical magazine.

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