eustasy

Eustasy refers to global changes in sea levels caused by variations in the volume of water in the world's oceans, often due to factors like melting or forming ice sheets, or changes in water storage on land. When ice melts, more water flows into the oceans, raising sea levels; when glaciers grow, they store water on land, causing sea levels to fall. These shifts happen over long timescales—thousands to millions of years—and are distinct from local sea level changes caused by land movements or sinking. Eustatic changes impact the entire planet equally, influencing coastlines and marine environments worldwide.