A recent study (Nature) has reported how ancient coastal habitats adapted as the last glacial period ended more than 10,000 years ago and projected how they are likely to change with this century’s predicted sea level rise. By examining the ocean sediments of ancient shorelines from a time when oceans rose rapidly, mainly because of melting ice sheets in the Northern Hemisphere, researchers inferred how ancient coastal habitats changed and formed the basis of improved predictions about the present. The study predicted higher global temperatures will provoke sea level rises that will lead to instability and profound changes to coastal ecosystems, including tidal marshes, mangrove forests, coral reefs and coral islands. Mangroves and tidal marshes act as a buffer between the ocean and the land and absorb the impact of wave action, prevent erosion and are crucial for biodiversity of fisheries and coastal plants. Under worst-case scenarios, these coastal habitats, buffeted by rising sea levels, will shrink and, in some cases, wash away, as they have in the distant past.