A groundbreaking study utilizing a century-old coral fossil has revealed that sea levels in the central Indian Ocean have been accelerating their rise since 1959, offering a more detailed understanding of regional climate change impacts.
Researchers, led by Professor Paul Kench from the National University of Singapore's Department of Geography, analyzed a microatoll—a unique coral formation that records annual sea-level changes in its skeletal layers, similar to tree rings. This ancient coral, discovered in the Maldives' Huvadhoo Atoll, provided a vital historical record extending the knowledge of sea-level changes in the region by an additional 60 years.
The findings indicate a significant increase in sea levels in the central Indian Ocean, with a total rise of 30 cm recorded between 1930 and 2019. The rate of ascent was 1.42 mm per year from 1930 to 1958, accelerating to 3.44 mm annually from 1959 onwards, and further increasing to 4.39 mm per year between 1992 and 2019. This acceleration aligns with global warming trends and shifts in wind patterns, which contribute to increased ocean heat absorption and thermal expansion.
Professor Kench highlighted that this early acceleration, starting around 1959, predates previous estimations based on satellite data and tide gauges. He described it as a clear indicator of human-driven climate change's impact, stating, "What we're seeing is a clear fingerprint of human-driven climate change etched into the skeletons of corals. The early acceleration in sea-level rise is a warning sign that the ocean has been responding to global warming far earlier and more strongly than we thought."
These insights are crucial for improving sea-level projections and coastal protection strategies. Singapore, for instance, is actively implementing measures to safeguard its coastlines. The nation's efforts include the Marina Barrage, a dam completed in 2008 for flood control and water supply, and ongoing research into engineering solutions combined with nature-based enhancements. The country is also developing a sophisticated coastal-inland flood model to simulate the combined effects of extreme sea levels and inland flooding, benefiting from this new data.
The study underscores the urgent need for comprehensive climate change mitigation and adaptation. The Indian Ocean, covering approximately 30% of the world's ocean area and supporting a significant portion of the global population, is particularly vulnerable. The accelerated sea-level rise, as evidenced by this coral fossil record, serves as a critical reminder of the interconnectedness of global climate systems and the imperative for proactive measures to protect vulnerable coastal communities and ecosystems.