A pioneering investigation by marine scientists based in Singapore has dramatically reshaped our understanding of sea-level rise in the Indian Ocean by revealing an earlier onset of acceleration than previously documented. Utilizing coral skeletons as precise environmental archives, the study offers an unprecedented, continuous record stretching back to the early 1900s. This breakthrough not only extends the timeline of oceanic changes but also establishes corals as a reliable proxy in tracing century-scale climate variability with exceptional resolution.
Published in Nature Communications, the international research effort was spearheaded by Professor Paul Kench of the National University of Singapore’s Department of Geography, in conjunction with experts from both NUS and Nanyang Technological University. Their meticulous analysis centered on coral cores extracted from the Maldives archipelago in the central Indian Ocean, where coral growth rings were examined using advanced geochemical and isotopic techniques to reconstruct detailed sea-level histories and climatic fluctuations over the past century.
By calibrating coral-derived sea-level records against instrumental data from tide gauges and satellite altimetry, the team successfully extended the documented sea-level chronology by approximately six decades, reaching back into the early twentieth century. This extended timeline provides an enriched historical framework fundamental for interpreting contemporary sea-level trends and associated climate dynamics, and it challenges earlier assumptions about when accelerated oceanic rise truly began in this critical marine region.
One of the key revelations of the study is the identification of a pronounced acceleration in sea-level rise commencing around 1959, considerably earlier than previously recorded by conventional coastal monitoring systems. This timing closely corresponds with intensified global temperature increases and accelerated cryospheric melt associated with anthropogenic greenhouse gas emissions. Consequently, the study elucidates the Indian Ocean’s heightened sensitivity to climatic perturbations over more than fifty years, reinforcing the urgency for proactive adaptation strategies.
Furthermore, the research quantifies a significant sea-level increase in the Indian Ocean of approximately 30 centimeters since the mid-twentieth century. Given that this body of water constitutes nearly one-third of the Earth’s oceanic surface and supports a similar fraction of the global human population, such a pronounced rise heightens the vulnerability of millions along coastal zones. The implications span amplified risks of flooding, shoreline erosion, intrusion of saltwater into freshwater aquifers, and degradation of essential ecosystems such as mangrove forests and coral reefs.
Professor Kench emphasized the importance of these findings by stating, “The coral skeletons carry an undeniable imprint of human-induced climate change, marking an earlier and more intense phase of sea-level rise than what traditional observations have suggested. This early acceleration serves as a stark indication that the climate system and ocean responses are more intimately linked and temporally aligned with anthropogenic forcing than we previously appreciated.”
The consequences of these findings extend well beyond regional coastal concerns, highlighting systemic challenges that affect global water security, agricultural productivity, and disaster risk reduction. Particularly for Singapore and neighboring Southeast Asian nations, this enriched long-term data lays the groundwork for refining climate models, thereby enhancing the precision of sea-level projections and empowering national efforts to develop resilient infrastructure and adaptive policies in the face of escalating oceanic threats.
This research also represents a methodological milestone, validating coral growth layers as highly reliable recorders of relative sea-level changes and extreme climate events. Corals, through their incremental skeletal accretion, encapsulate critical environmental parameters analogous to dendrochronological records in trees. By analysing variations in the density, isotopic composition, and elemental signatures embedded within coral bands, the study decodes past ocean temperatures, salinity fluctuations, and sea levels with an unprecedented degree of accuracy.
Importantly, the study demonstrates the successful calibration of coral proxy data with direct sea-level measurements, confirming a strong concordance over recent decades. This cross-validation not only reinforces coral-derived records as trustworthy archives but also enhances confidence in their application to paleoenvironmental and paleoclimatic reconstructions, thereby extending the observational baseline far beyond the limits of instrumental datasets.
Beyond chronicling long-term sea-level trends, the coral archives distinctly captured episodes of climatic extremes, including anomalous warming and cooling phases and periods of drought. These signals align convincingly with historic meteorological records, underscoring corals’ capability to serve as nuanced indicators of environmental variability and extreme events. This dual capacity to track mean trends and episodic perturbations offers invaluable insights into the natural variability and anthropogenic influence shaping the Indian Ocean climate.
The interdisciplinary approach underpinning this work, integrating marine biology, geochemistry, climatology, and oceanographic sciences, epitomizes the advancements achievable when diverse scientific lenses converge to address multifaceted environmental challenges. Furthermore, the study exemplifies Singapore’s burgeoning role at the forefront of climate change research, reinforcing its status as a hub for cutting-edge marine and environmental sciences with tangible global relevance.
Presented at the Asia Oceania Geosciences Society conference in 2025 and subsequently featured in prominent journals, the publication stands as a seminal contribution to paleoclimate research. It propels forward the use of natural archives in reconstructing past oceanic conditions and provides critical foundations for anticipating future impacts under ongoing global warming trajectories. As coastal communities worldwide grapple with rising seas, the insights gleaned from these coral records furnish a vital scientific compass for resilience planning and adaptive management.
In closing, this landmark study not only rewrites the timeline of sea-level acceleration in the Indian Ocean but also offers a replicable framework for employing marine biogenic proxies in environmental history. It underscores the urgency of integrating paleo-records into contemporary climate adaptation dialogues, thereby bridging the past and future in the pursuit of sustainable human-ocean coexistence amid an era of unprecedented climatic change.
Subject of Research: Sea-level acceleration and climatic variability in the Indian Ocean recorded by coral growth
Article Title: Coral growth records 20th Century sea-level acceleration and climatic variability in the Indian Ocean
News Publication Date: 1 July 2025
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DOI: 10.1038/s41467-025-60972-2
Keywords: Coral reefs, Marine biology, Sea-level rise, Paleoclimate, Indian Ocean, Climate variability
