Rising acidity in the ocean caused by seas absorbing greenhouse carbon dioxide could make low-lying island nations like Kiribati and the Maldives more vulnerable to storms.
Scientists say carbon dioxide in the atmosphere is at its highest level in the past 650,000 years, possible 23 million years, and half has now been dissolved into the oceans making them more acidic.
Ocean acidification, which is projected to spread extensively north from the Antarctic by 2100, makes it difficult or impossible for some animals, like coral and starfish, to produce their shells and skeletons.
A new report by some of the world's leading marine scientists says if ocean acidification weakens the structure of reef-forming corals and algae, tropical islands will be more vulnerable to physical impacts from storms and cyclones.
The report cited Kiribati and the Maldives in the Indian Ocean as being more vulnerable to tropical storms if ocean acidification continues to rise.