Lots of tropical islands barely peek above the ocean’s surface, reaching no more than several feet at their highest points.

And now their future is imperilled as sea levels rise around the world, potentially displacing hundreds of thousands of people and creating geopolitical crises in parts of the world, according to a new report published in Science Advances.

By 2050, thousands of tropical islands may become uninhabitable — a conservative estimate, according to the report.

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In addition to land becoming swallowed by oceans, drinking water supplies on these islands will be flooded with saltwater as waves become more intense and storms become more frequent, the report argues.

As a result, hundreds of thousands of people may be displaced in the decade ahead, adding to the already-booming refugee crisis caused by climate disasters.

“This information will also be critical to political leaders, not only of island nations but also globally, for understanding how climate change will determine when these islands will no longer be able to support human habitation, resulting in an extensive displacement of human populations,” the authors wrote.  

“If these impacts are not addressed or adequately planned for, as it becomes necessary to abandon or relocate island nations,” they continued, “then significant geopolitical issues could arise.”

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Many of these islands are already becoming harder to live on as water supplies become compromised by saltwater, according to the report.

Saltwater intrusion is an increasing problem in coastal communities around the world, harming agriculture, water supplies, and infrastructure.

The Marshall Islands, for example, are fast becoming uninhabitable due to saltwater intrusion, according to the report.

A collection of 1,100 low-lying islands on 29 atolls, the report writes that conditions throughout the territory will become too extreme to endure sometime after 2030.

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“It’s a scary scenario for us,” Hilda Heine, president of the Marshall Islands told the Denver Post.

The report was funded in part by the US Department of Defense which has military operations on numerous tropical islands, according to the Denver Post.

As climate change challenges the viability of these places, military infrastructure will also be damaged, according to the DOD.

“This study provided a better understanding of how atoll islands may be affected by a changing climate,” Defense Department spokeswoman Heather Babb said in a statement.

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“While no decisions have been made about Department of Defense activities on the islands based on the study, DOD continues to focus on ensuring its installations and infrastructure are resilient to a wide range of threats,” she added.

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