The Asia Sea-Level Knowledge Hub (ASK‑Hub) is a new international initiative that will integrate paleo records, modern observations, and probabilistic projections to advance regional understanding of relative sea-level (RSL) change and extreme events to deliver actionable coastal risk assessments for Southeast and East Asia.

Our research has shown geological reconstructions from the Sunda Shelf provide the long-term context underpinning ASK‑Hub’s scientific framework, documenting ~121 m of RSL rise since the Last Glacial Maximum (~20 ka) with peak rates approaching 15 mm yr⁻¹ and large-scale inundation (~2.3 million km²). Early Holocene rise (−21 to −1 m; 10–7 ka) and a mid-Holocene highstand of up to +4 m (~5 ka) reveal systematic misfits with glacial isostatic adjustment models, highlighting unresolved regional processes that the Hub targets through integrated datasets and modelling.

Holocene paleo‑reef records across the Indo-Pacific further demonstrate the sensitivity of coastal systems to RSL rise, a key focus of ASK‑Hub’s risk assessments. Reef accretion is unlikely (>90% probability) to keep pace once RSL rise exceeds ~5.3 mm yr⁻¹, implying that 76% of reef sites lack the capacity to match projected high-emissions sea-level rise and face severe risk of submergence within ~35 years. This threshold behaviour provides a critical process-based constraint for evaluating ecosystem resilience and coastal protection under future scenarios.

Extending into the observational era, new proxy records from Indonesian coral microatolls, combined with data archaeology in Singapore, reduce uncertainties by ~50% and establish a robust baseline of near-stable RSL (0.1 ± 0.1 mm yr⁻¹) from the late 19th century to 1993. A subsequent acceleration to 4.0 ± 0.1 mm yr⁻¹ exceeds global averages and reflects coupled ocean warming and vertical land motion, underscoring the need for regionally resolved monitoring—central to ASK‑Hub’s observing system.
Incorporating vertical land motion into projections aligns with ASK‑Hub’s objective to produce decision-relevant forecasts. This yields a likely (17th–83rd percentile) RSL rise of 0.75 m (0.58–1.04 m) by 2100 under high emissions, with a 95th percentile of 2.2 m from a unified probabilistic framework. Even under moderate emissions, projected rates approach those observed only during abrupt ice-mass loss events (~14.5 and ~9 ka), emphasizing the exceptional nature of ongoing change.

ASK‑Hub will build on this evidence chain by further integrating satellite altimetry, tide gauges, geological archives, and climate models to resolve regional variability, subsidence, and compound flooding risk. Through an open-access platform aligned with FAIR and CARE principles and co-designed with policymakers and stakeholders, the Hub will translate cutting-edge science into actionable adaptation strategies. ASK‑Hub aims to provide a robust, policy-relevant foundation for coastal resilience in one of the world’s most vulnerable regions.
 

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