Sea level rise is a global issue, but in the coming decades Asia is likely to feel the worst effects because of the number of people living in low-lying coastal regions. Small island states could also face particularly devastating losses. For example, in the Maldives in the Indian Ocean about one-third of the population live on land that could be underwater before the end on the century. It is vital that the changing height of the sea surface continues to be closely monitored over the coming decades. Copernicus Sentinel-6 is the key mission undertaking this important role until at least 2030.