Overview A recent Nature paper reveals that about 90% of existing sea‑level impact studies have underestimated the baseline coastal water height by an average of 30 cm . The error is most pronounced in the Global South , especially the Pacific and Southeast Asian coasts. Key Developments Meta‑analysis of hundreds of studies shows a systematic 30 cm under‑estimation of coastal water levels. Correcting the baseline could increase projected inundated land by up to 37% and expose an additional 77‑132 million people to flood risk. The mismatch stems from differing measurement methods for sea and land elevations, a “methodological blind spot” highlighted by hydrogeology experts. Island nations in the Indo‑Pacific report the largest discrepancies. Important Facts • Sea level rise of just over 1 m by 2100 could affect far more land than previously modelled. • Researchers such as Philip Minderhoud (hydrogeology professor, Wageningen University) and Katharina Seeger (University of Padua) stress that satellite and land‑based models often ignore local wave, tide and current dynamics. • Climate activist Vepaiamele Trief from Vanuatu illustrates on‑ground impacts: shoreline retreat, uprooted trees, and roads rerouted inland. UPSC Relevance The study touches upon several GS‑paper themes: GS‑3 (Environment & Ecology): Understanding measurement errors in climate change impact assessments. GS‑1 (Geography & International Relations): The vulnerability of the Global South and small island developing states. GS‑2 (Polity): Policy implications for coastal planning, disaster management, and international cooperation under frameworks like the UNESCO report on ocean carbon sinks. Way Forward 1. Standardise measurement protocols for sea and land elevations, integrating tide‑gauge data with satellite observations. 2. Revise national coastal risk models to incorporate the corrected baseline, especially for vulnerable Indo‑Pacific nations. 3. Strengthen community‑level adaptation – early warning systems, relocation planning, and livelihood diversification for at‑risk coastal populations. 4. Enhance international collaboration through bodies like UNESCO to share best practices and funding mechanisms.