Sea-level rise is arguably one of the most serious consequences of the climate crisis. Satellites are essential to measuring the individual components that contribute to the overall rise. These physical processes causing global sea-level rise are highlighted in the animation. The main causes are thermal expansion of oceans, as they accumulate the excess heat caused by greenhouse gas emissions, the melting of ice from the ice sheets and glaciers, as well as changes in land water storage such as lakes.

Global mean sea-level has risen by more than 30 millimetres per decade since precise satellite measurements began in the 1990s. A good third of this rise in sea level is down to thermal expansion – as seawater warms, it expands. Nearly two thirds of the rise is because of freshwater being added to the ocean, mainly through the melting of land ice. Another addition of water to the ocean results from a decrease of water on land, such as groundwater storage. Scientists assess how these different contributions compare with the overall change in sea level – in other words, they assess the sea-level budget.