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Scientists discover 657 new islands

The Earth has many more barrier islands than previously thought, a global survey has found.

By OurAmazingPlanet Staff / April 19, 2011

Activists gather on an island on the Belizian Barrier Reef off the coast of Belize City in November 2010. Many barrier islands are under threat from development, just as global sea levels are rising.

UPI/Lou Dematteis/Spectral Q/Newscom/Fule

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Here's something you don't see every day – hundreds of new islands have been discovered around the world.

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The Earth has 657 more barrier islands than previously thought, according to a new global survey by researchers from Duke University and Meredith College in Raleigh, N.C.

The researchers identified a total of 2,149 barrier islands worldwide using satellite images, topographical maps and navigational charts. The new total is significantly higher than the 1,492 islands identified in a 2001 survey conducted without the aid of publicly available satellite imagery.

Barrier islands often form as chains of long, low, narrow offshore deposits of sand and sediment, running parallel to a coast but separated from it by bays, estuaries or lagoons. Unlike stationary landforms, barrier islands build up, erode, migrate and rebuild over time in response to waves, tides, currents and other physical processes in the open ocean environment.

All told, the world's barrier islands measure about 13,000 miles (21,000 kilometers) in length. They are found along all continents except Antarctica and in all oceans, and they make up roughly 10 percent of the Earth's continental shorelines. The northern hemisphere is home to 74 percent of these islands.

Barrier islands help protect low-lying mainland coasts against erosion and storm damage, and can be important wildlife habitats. The nation with the most barrier islands is the United States, with 405, including those along the Alaskan Arctic shoreline.

"This provides proof that barrier islands exist in every climate and in every tide-wave combination," said study team member Orrin H. Pilkey of Duke University. "We found that everywhere there is a flat piece of land next to the coast, a reasonable supply of sand, enough waves to move sand or sediment about, and a recent sea-level rise that caused a crooked shoreline, barrier islands exist."

There, but overlooked

The newly identified barrier islands didn't miraculously appear in the last decade, said study team member Matthew L. Stutz of Meredith. They've long existed but were overlooked or misclassified in past surveys.

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