Climate Change Research


Interpretation of IPCC AR6 report: monitoring and projections of global and regional sea level change

ZHANG Tong1, YU Yong-Qiang2, 3, XIAO Cun-De1, HUA Li-Juan4, YAN Zhan1   

  1. 1 State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China;
    2 State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China;
    3 University of Chinese Academy of Sciences, Beijing 100049, China;
    4 State Key Laboratory of Severe Weather (LASW), Chinese Academy of Meteorological Sciences, Beijing 100081, China
  • Received:2021-10-08 Revised:2021-10-25 Online:2021-11-17 Published:2021-11-17
  • Contact: Cunde 无Xiao

Abstract: In the IPCC Sixth Assessment Report, the latest monitoring and simulation results indicate that the current rate of sea level rise is accelerating (3.7 mm/a) and will continue to rise in the future, showing an irreversible trend. Under low emission scenarios (SSP1-1.9) and high emission scenarios (SSP5-8.5), global mean sea level (GMSL) is projected to rise by 0.15-0.23 m and 0.20-0.30 m by 2050, respectively. By 2100, GMSL is projected to rise 0.28-0.55 m and 0.63-1.02 m, respectively. Antarctica ice sheet instabilities are significant sources of uncertainty affecting future sea level rise projections. Regional relative sea level rise is an important driving factor affecting extreme still water levels. Marine Ice Sheet Instability (MISI) and Marine Ice Cliff Instability (MICI) and the acceleration of ice streams will increase the estimated GMSL in the future. After 2100, with the continuous heat uptake of deep ocean and the continuous loss of ice sheet mass, sea level rise will last for thousands of years (high reliability). A major deficiency of present-day sea-level studies is the prediction of high sea-level scenarios at the end of the 21st century. Under the impacts of climate warming and polar amplification effect, the collapse of Antarctic ice shelf may accelerate. The intensification of hydrofracturing process and ocean stratification can increase the melting on and beneath the ice shelf, respectively. However, these physical processes have not been well implemented in the models. By the end of the 21st century, the tidal amplitude in most coastal regions of the world will change significantly. Human factors such as land reclamation and different land management policies in coastal areas will affect the impact of global sea level rise on tidal amplitude. Therefore, the impact of ice sheets on global and regional sea level changes has important practical and long-term significance for China’s future coastal infrastructure and ecological environment protection.

Key words: Global mean sea level (GMSL), Regional extreme sea level, Ice sheet change, Marine dynamic processes

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