Global sea levels are up to 0.3 meters higher than thought, putting 77–132 million more people at risk.

A new study reveals global coastal sea levels are up to 0.3 meters higher than previously estimated, with 90% of past research underestimating baseline levels due to reliance on outdated gravitational models rather than direct measurements. The error, especially pronounced in Southeast Asia, the Pacific, and the Americas, could mean 37% more land is at risk, threatening 77 million to 132 million people. Coastal subsidence in cities like Miami, New Orleans, and San Francisco worsens flooding risks, with high-tide flooding already increasing. Experts urge updated sea-level assessments to improve climate policy, adaptation planning, and funding.