Professor CHEN Jianli, Chair Professor of Space Geodesy and Earth Sciences at The Hong Kong Polytechnic University (PolyU) and his research team have made a significant breakthrough in climate science by establishing the first precise 30-year record (1993–2022) of global ocean mass change, a critical factor in the rise of global mean sea level (GMSL).
The team’s pioneering work utilises advanced space geodetic technologies, specifically time-variable gravity field data derived from satellite laser ranging (SLR), to deliver real-time, high-precision measurements of essential climate indicators such as sea level, wind speed and direction, atmospheric humidity, and rainfall intensity. By implementing an innovative forward modelling technique that incorporates detailed geographic information of ocean-land boundaries, the researchers have overcome previous limitations in spatial resolution, enabling accurate long-term monitoring of global ocean mass changes.
Published in the prestigious Proceedings of the National Academy of Sciences, the study reveals that GMSL has been increasing at an average rate of approximately 3.3 mm per year, with a marked acceleration observed in recent years. The findings indicate that around 60% of the 90 mm global average sea-level rise between 1993 and 2022 is attributable to ocean mass increase, primarily driven by the accelerated melting of land ice, particularly in Greenland. Notably, over 80% of the total increase in global ocean mass during this period is due to the loss of polar ice sheets and mountain glaciers.
Professor CHEN commented, “In recent decades, climate warming has led to accelerated land ice loss, which has played an increasingly dominant role in driving global sea-level rise. Our research enables the direct quantification of global ocean mass increase and provides a comprehensive assessment of its long-term impact on the sea-level budget. This offers crucial data for validating coupled climate models used to project future sea-level rise scenarios.”
Dr NIE Yufeng, Research Assistant Professor of LSGI and lead author of the study, added, “The research showed that the ocean mass changes derived from SLR analysis align well with the total sea level changes observed by satellite altimeters, after accounting for the effect of ocean thermal expansion. This demonstrates that the traditional SLR technique can now serve as a novel and powerful tool for long-term climate change studies.”
This outstanding achievement by Professor CHEN and his team exemplifies RICRI’s commitment to advancing climate monitoring and research. Their work provides vital data for understanding the complexities of global climate change and supports the development of effective strategies for mitigation and adaptation.
