Coral-fringed tropical atolls rank among landforms most threatened by global warming. Healthy ecosystems may help these islands keep pace with rising seas.
Nick Graham, marine ecologist at Lancaster University in the United Kingdom, led an international team that studied island resilience across 28 atoll islands in the Pacific and Indian oceans. Their paper, published Wednesday in Science Advances, shows that restoring atoll ecosystems reinforces their growth. Atoll islands with native vegetation and thriving seabird populations are "naturally active systems that can change and adapt to their environmental conditions if they are allowed to do so."
Seabirds ferry nutrients from the open ocean and deposit them on atolls as guano that nurtures land plants, marine life and coral growth. This provides more material for reef building: parrotfish and other reef feeders turn dead coral into sand to maintain beaches, while native plants with extensive root networks stabilize sediments. Eradicating rats and replacing coconut plantations with native forests and brush could give some atolls a "fighting chance" to persist at the rate of sea-level rise expected toward the end of the century with about 2° Celsius (3.6° Fahrenheit) of warming.
Restoring wetlands and forests dampens swings between wet and dry spells, reducing flood and fire hazards. Restoration efforts can also slow global warming by supporting natural carbon storage. On the 28 atoll islands the team studied, strengthening the dynamic system of seabirds, native vegetation, and reef systems starts a virtuous cycle as ecosystems become better able to sustain themselves and build resilience to growing impacts.