At a Glance

Many Pacific atoll islands will be rendered uninhabitable between the 2030s and 2060s, researchers say.Flooding from rising seas will impact their drinking water.Island inhabitants will have to move or significant financial investments will need to be made for new infrastructure.The northwestern Hawaiian Islands,Caroline Islands, Cook Islands, Gilbert Islands, Line Islands, Society Islands, Spratly Islands, Maldives andSeychelles are threatened.

Wave-driven flooding from rising seas will leave many Pacific islands uninhabitableby mid-century, a new study says.

Many atoll islands according to the study published Wednesday in Science Advances.

"This annual flooding will result in the islands becoming uninhabitable because of frequent damage to infrastructure and the inability of their freshwater aquifers to recover between overwash events," according to the study.

The authors predict that at current greenhouse gas emission rates, most of these Pacific atoll islands will be rendered uninhabitable between the 2030s and 2060. Island inhabitants will be forced to move or the governments will have to makesignificant financial investments for new infrastructure to provide water to residents.

The study was commissioned by the U.S. Defense Department because many of these atollislands are home to American military sites.

Wave-driven flooding and overwash on Roi-Namur Atoll.

(Peter Swarzenski/U.S. Geological Survey)

The scientists usedclimate projections with weather and wave modeling to study the Kwajalein Atoll, home to the Ronald Reagan Ballistic Missile Defense Test Site, according to a press release.

They say the study is relevant to thousands of other atoll islands in the Pacific and Indian oceans, includingthe northwestern Hawaiian Islands,Caroline Islands, Cook Islands, Gilbert Islands, Line Islands, Society Islands, Spratly Islands, Maldives andSeychelles.

“The tipping point when potable groundwater on the majority of atoll islands will be unavailable is projected to be reached no later than the middle of the 21st century,” said Curt Storlazzi, United States Geological Survey geologist and lead author of the new report.

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Storlazzi noted that other studies have looked primarily at rising seas alone without considering wave-driven flooding and overwash.

“Such information is key to assess multiple hazards and prioritize efforts to reduce risk and increase the resiliency of atoll islands' communities around the globe,” Storlazzi said.

The authors note thatthe primary source of freshwater for populated atoll islandsis rain that soaks into the ground. Overwash events allow salt water to contaminate the freshwater aquifer.

“Rainfall later in the year is not enough to flush out the saltwater and refresh the island’s water supply before the next year’s storms arrive repeating the overwash events,” said Stephen Gingerich, co-author of the report and USGS hydrologist.