Understanding the natural resilience and challenges faced by atoll islands in the context of climate change.
Rather than atoll islands’ low elevation per se, it is the impairment of natural accretion processes that is jeopardising their persistence.
The commonly held belief that atoll islands are static and doomed landforms due to rising sea levels is a misunderstanding. In reality, these islands have the ability to adapt and grow vertically. This natural capacity for vertical accretion enables them to keep pace with gradual sea level changes, challenging the idea of inevitable loss.
Natural processes and threats
Atolls are unique island formations made up of a variety of materials, including sand and boulder-sized debris, which come from the surrounding coral reefs. These materials are brought to the atoll rims by ocean currents and waves. Atolls continuously change in shape, size, and height in response to environmental factors. Typically, these islands are situated at elevations ranging from 1 to 5 metres above sea level and have the ability to naturally increase in height at rates that correspond to the projected sea-level rise of 3 to 10mm per year.
The main threat to these islands is not their low elevation, but rather the damage caused to their natural growth processes. Both global impacts, such as coral reef degradation from marine heatwaves and acidification, and local impacts, like sediment disruption from coastal development, significantly hinder their ability to grow and maintain their surface above the water.
Empowering local action
Contrary to the fatalistic view of atoll 'drowning', current advancements in atoll geoscience and ecology offer hope. Promoting the notion that atolls are irreversibly sinking underestimates the power of place-based solutions and diminishes the role of local communities and Indigenous knowledge systems in conservation efforts.
To ensure the survival and health of atoll islands, it is crucial to maintain the natural processes of sediment production on coral reefs and ensure unobstructed sediment transport from the reefs to the islands. Effective conservation must involve both reducing global greenhouse emissions and locally restoring and preserving these accretion processes.
The main threat to these islands is not their low elevation, but rather the damage caused to their natural growth processes.
Nature-based solutions
Practical measures to enhance atoll resilience involve managing marine protected areas to support key species such as parrotfish. These species play a vital role in producing the sand-grade sediment required for island formation. Additionally, innovative techniques like coral out-planting show potential for restoring essential sediment production necessary for island stability.
Local conservation actions can greatly improve the coral reef 'sediment factory', contributing to a steady supply of building material for atoll growth. For example, community-driven initiatives can directly improve the health of the reef and, in turn, the island's resilience to sea level rise.
Substantial potential
The future of atoll islands hinges on understanding and supporting their natural growth mechanisms. By integrating ecological knowledge with geophysical processes and community involvement, there is substantial potential to not only preserve but also enhance the resilience of these unique ecosystems against the challenges posed by climate change.
