Most of the observed sea level rise (about 3 mm per year) is coming from the meltwater of land-based ice sheets and mountain glaciers, which adds to the ocean’s volume (about 2 mm per year combined), and from thermal expansion, or the ocean water’s expansion as it warms (roughly 1 mm per year).

Changes in land water storage (e.g., water stored behind dams or withdrawn from underground aquifers, changes in global precipitation patterns and torrential rainfalls) also make a small contribution. Scientists also factor in vertical land motion changes due to subsidence and/or the rebounding of Earth’s crust since the end of the Last Glacial Maximum.

Recently, spaceborne instruments have detected accelerations in ice sheet mass losses and sea level rise, which is expected when the globe warms, based on our understanding of Earth’s history and climate physics.

You can read more about what is causing the rise and how we observe sea level change.