According to the research team, on average, current sea level is 24 or 27 centimeters higher than in two commonly used Earth models, EGM96 and EGM2008. 4 meters for EGM2008. These extreme cases occur mainly when too few on-site measurement data are available for model calculations.
5 to 2 meters according to estimates based on such Earth models. Satellite data for land height often assumes the zero line as sea level height, leading to large inaccuracies, as land height and local sea level are measured with different satellites and often relative to different vertical reference surfaces of zero meters, making data integration difficult. Even in studies using concrete sea level measurement data, most researchers had difficulties correctly assigning coastal sea level information to land height data, with Seeger and Minderhoud finding only one study where all calculations for comparing height data were performed correctly.
Scientists from the Global North developed the Earth models, which are significantly more precise in Europe and North America than in the Global South. The specific regions or countries most affected by the underestimation of sea levels have not been detailed, and it is unclear how many people are currently at risk due to this underestimation, not just from a future one-meter rise.