Photo: Unsplash/Guillaume Bassem
A new study suggests that the primary cause of global sea level rise is not only melting glaciers, but the thermal expansion of the oceans themselves, according to research reported by Science Alert.
As ocean water warms, it expands in volume — a process known as thermal expansion — causing sea levels to rise even without additional water from melting ice.
Researchers analyzed data spanning multiple periods, including 1960–2023 (tide gauges and satellite data), 1993–2023 (satellite era), and 2005–2023 (Argo ocean float measurements). They found that global sea level has been rising at an accelerating rate, from about 2.06 mm per year since the 1960s to 3.94 mm per year between 2005 and 2023.
According to the study, the contributions to sea level rise are distributed as follows:
- 43% — ocean thermal expansion
- 27% — melting mountain glaciers
- 15% — Greenland ice sheet
- 12% — Antarctic ice sheet
- 3% — changes in land water storage
Scientists say improved measurement systems and higher-resolution satellite data have helped close previous gaps in explaining observed sea level changes.
They also warn that ongoing warming — especially in the Southern Ocean and around Antarctica — could further accelerate sea level rise in the coming decades, even under mitigation scenarios.
