Wageningen University 的新研究显示，全球实际平均海平面已比多数常用模型假设高约 30 公分（0.30 公尺），表示许多沿海风险被系统性低估。差距在不同地区差异很大，最大出现在东南亚与大洋洲；在部分海岸线，实际海面比既有冲击评估假设高出约 1.0 至 1.5 公尺。Philip Minderhoud 指出，若某个岛屿或沿海城市的实际海平面高于先前假设，海平面上升冲击将比原先投影更早发生。

研究估计，若到 2100 年海平面上升 1.0 公尺，将比先前预测多出约 7,700 万至 1.32 亿（77–132 million）沿海居民落在海平面以下。关键原因是，多数既有研究依赖以地球重力与自转为基础的 geoid 模型来表示海岸地表高程，并常将 geoid 高度视为现今平均海平面。实际上，风、洋流、海水温度与盐度都会改变海平面，而 Katharina Seeger 表示仅约 1% 既有论文有正确结合陆地高程与实测海平面。

外部专家同意这些结果提高了沿海调适的急迫性，但也强调把全球海平面问题转译到区域与地方尺度仍然困难，政策是否能纳入新方法仍待观察。观测上，过去 100 年海平面约上升 20 公分（0.20 公尺）；Anders Levermann 指出，虽然海洋对气候变迁反应较慢，已发生的 1.5°C 暖化最终可能承诺约 3 至 4 公尺的长期上升，显示目前评估与防护标准可能仍偏保守。

New research from Wageningen University finds that actual mean sea level is already about 30 cm (0.30 m) higher globally than assumed in most standard models, indicating that many coastal risks have been systematically underestimated. The gap varies strongly by region and is largest in Southeast Asia and Oceania; on some coastlines, actual ocean level is about 1.0 to 1.5 m above levels assumed in typical impact assessments. Philip Minderhoud said that if real sea level for a specific island or coastal city is higher than previously assumed, sea-level-rise impacts will arrive earlier than earlier projections indicated.

The study estimates that if sea level rises by 1.0 m by 2100, about 77 to 132 million more coastal residents would fall below sea level than previously predicted. A central reason is that most existing studies rely on geoid models, based on Earth’s gravity and rotation, to represent coastal land elevation, and often treat geoid height as present mean sea level. In reality, sea level is also shaped by winds, ocean currents, seawater temperature, and salinity, and Katharina Seeger said only about 1% of existing publications properly combine land elevation with measured sea level.

External experts agree the findings raise the urgency of coastal adaptation, while stressing that translating a global sea-level problem to regional and local protection scales remains difficult and policy uptake is still uncertain. Observationally, sea level has risen about 20 cm (0.20 m) over the last 100 years; Anders Levermann noted that although ocean response to climate change is slow, the 1.5°C warming already reached could eventually commit the world to about 3 to 4 m of long-term rise, implying that current risk baselines and defense standards may still be conservative.