For over three decades, satellites orbiting Earth have measured the height of the ocean surface with remarkable precision. These measurements are crucial because changes in ocean height are one of the clearest indicators of how our planet is responding to climate change. Rising ocean surfaces signal warming temperatures, melting ice and shifting ocean currents.
These all directly affect coastal communities through flooding, erosion and habitat loss. Even a small rise in the baseline sea level means that normal tidal cycles and storm surges reach further inland. This can turn high tides into damaging flood events.
Many people assume ocean levels are uniform, like water sitting flat in a bathtub. In reality, the ocean surface is surprisingly uneven. Winds push water in certain directions. Ocean currents redistribute heat. Temperature differences cause water to expand or contract. Even variations in Earth’s gravity field create bumps and dips in the sea surface. All these factors combine so that sea level can vary by tens of centimetres from one region to another.
