Overview
- Researchers Katharina Seeger and Philip Minderhoud examined 385 peer-reviewed studies from 2009 to 2025 on coastal exposure to sea-level rise.
- About 90% of prior analyses used geoid or satellite baselines rather than locally measured sea levels, leading to an average 30-centimeter underestimate at the coast.
- Recalibrating the baseline would increase projected inundated land by up to 37% under roughly 1 meter of rise and add an estimated 77–132 million people to those at risk.
- The study estimates around 80 million people already live below sea level, with the largest biases in the Indo-Pacific, Southeast Asia and parts of Latin America, while Europe shows smaller gaps.
- External scientists note the issue is recognized and some local planners already correct for it, suggesting impacts will vary regionally and warrant targeted reassessments and better dataset alignment.