Not only are many of the world's smallest islands at risk of sinking below the ocean, the majority of them could now be in danger of drying out because of climate change.
Researchers have estimated 73 percent of the world's small island nations could become more arid by 2050, affecting nearly 16 million people.
In the study, published today in Nature Climate Change, author Kristopher Karnauskas and colleagues from the University of Colorado Boulder developed a way to calculate the difference between precipitation -- generally made up of rainfall -- and evaporation for 80 island groups around the world.
It's previously been difficult to assess aridity on small islands, like French Polynesia and the Marshall Islands, because of their size.
The researchers say while around half of the islands, mostly in the deep tropics, will see more rain, increases in evaporation were more consistent across the islands. Overall, growing rates of evaporation more than outweigh the increased rainfall.
Islands closer to home that could be affected include the Cook Islands, Christmas Island and Cocos (Keeling) Islands.
The potential fresh water problems have important implications for vulnerable populations on small islands as they adapt to a changing climate.