The rise of sea level and tropical storms threaten coral reefs and the low-lying islands that depend on them. However, an investigation conducted at Funafuti Atoll, in Tuvalu, shows that the response of these systems to climate change may be more complex than previously thought. Based on surveys conducted over 120 years, a team of researchers from Australia and New Zealand concluded that the physical structure and ecology of the reef platform remained relatively stable, despite sea-level rise and the occurrence of tropical storms.
“The results challenge the idea that rising sea levels will inevitably destabilize coral islands,” says Paul Kench, Pro Vice-Chancellor for Science, Technology, Engineering and Mathematics at the University of Waikato and the study’s lead author. An intense tropical cyclone in 1972 damaged part of the reef edge and deposited large quantities of coral fragments on its surface. In the following decades, waves and storms transported that material toward the island.
As a consequence, “the island crest rose by about 1.4 meters in height, while the coastline remained in a similar position,” Kench notes. The process shows how sediments derived from the reefs can contribute to altering the elevation of islands, even as sea level rises.
“Coral reefs, storms, waves and sediments can interact in ways that allow islands to naturally adapt to changing sea levels,” the researcher notes. Still, the results pertain to a specific system and do not mean that all coral islands will be able to respond in the same way. The capacity to adapt will depend on the characteristics of each location and future environmental conditions.
The study highlights the importance of monitoring reefs and islands over long periods to better understand their evolution. In the context of climate change and sea-level rise, this knowledge could help assess the vulnerability of Pacific coastal systems and identify the natural processes that influence their capacity to adapt.
