Is sea-level rise turning out to be worse than expected? A major new study suggests that, in many places, the danger has been underestimated—not because the ocean suddenly surged overnight, but because researchers often started from the wrong baseline. In a March 2026 paper in Nature, scientists reviewed 385 coastal hazard studies and found that most did not properly match land-elevation data with actual local sea-level measurements. Their conclusion is striking: average coastal sea level is about 0.3 meters higher than many assessments assumed, and in parts of Southeast Asia and the Indo-Pacific the gap can reach around 0.9 to 1.1 meters. (nature.com)
That error matters because risk calculations are highly sensitive to small changes in elevation. The Nature study estimates that, under a hypothetical 1 meter of relative sea-level rise, properly referenced data would place 31–37% more land below sea level and raise the exposed population by 48–68%, to roughly 77–132 million people. In other words, some coastal communities may hit dangerous flood thresholds sooner than planners expected. The researchers argue that existing impact assessments, climate-finance decisions, and adaptation plans now need to be re-evaluated. (nature.com)
This warning becomes even more serious when combined with the broader long-term trend. NASA says global mean sea level has risen about 10 centimeters since 1993, and the annual rate of rise has more than doubled over the past three decades. Although 2025 saw only a small annual increase because La Niña temporarily shifted more water onto land, NASA stresses that this slowdown is short-lived and does not change the upward trajectory. The IPCC still projects global mean sea level rise of 0.28 to 1.01 meters by 2100 relative to 1995–2014, while NOAA says the United States is likely to experience as much sea-level rise by 2050 as it saw over the entire previous century. The message is clear: coastal risk is not just about how much the sea will rise in the future, but also about whether we have measured today’s starting line correctly. (jpl.nasa.gov)
