False Alarm: Small Pacific Islands Growing, Not Sinking, As Sea Levels Rise

  • Date: 05/06/15
  • Penny Sarchet, New Scientist

Rising seas are eating away at small islands and will eventually turn their inhabitants into climate refugees, right? Not so for some of the world’s most threatened islands, which have grown despite experiencing dramatic sea level rise.

<i>(Image: Ashley Cooper/Visuals Unlimited, Inc.)</i>

(Image: Ashley Cooper/Visuals Unlimited, Inc.)

Funafuti atoll, which includes the capital of Tuvalu, is an islet archipelago in the tropical Pacific Ocean made from coral debris washed up from an underlying reef by waves, winds and currents. Over the past 60 years the sea has risen by around 30 centimetres locally,sparking warnings that the atoll is set to disappear.

But Paul Kench of the University of Auckland, New Zealand, and colleagues found no evidence of heightened erosion. After poring over more than a century’s worth of data, including old maps and aerial and satellite imagery, they conclude that 18 out of 29 islands have actually grown.

As a whole, the group grew by more than 18 hectares, while many islands changed shape or shifted sideways.

“There is still considerable speculation that islands will disappear as sea level rises,” says Kench. “Our data indicates that the future of islands is significantly different.”

Storms and other disturbances that churn up the sea seem to be more important than sea level in influencing stability, says Kench. Storms break up coral, which then gets deposited on the atolls. He says other coral reef islands are likely to evolve in the same way, and that the Maldives seem to be showing a similar effect.

“There is presently no evidence that these islands are going to sink,” saysVirginie Duvat of the University of La Rochelle in France. She says that she and other researchers are trying to fight the widespread misconception that sea level rise will mean the end for atolls. However, Kench’s findings do not apply to other types of island, like the volcanic main islands of Fiji, Tonga and Samoa.

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