近20年海平面变化成因研究进展及挑战

The causes of contemporary sea level rise over recent two decades:progress and challenge

揭示海平面变化成因有助于深入认识当前的全球气候变化,并做出积极应对。空间大地测量技术及海洋浮标观测极大地促进了对全球及区域海平面变化成因的研究,有效弥补了海洋模式对长期趋势估计不准确的缺点,有助于理解海平面长期趋势及年际变化的驱动因素。本文系统回顾了近20年关于海平面上升成因的研究进展,分析了陆地质量迁移不同成分对海平面上升的贡献。多源观测数据表明,海水质量增加贡献了2/3的海平面上升,其余1/3由海水热膨胀引起。由于气候变暖趋势没有减弱,陆地冰川消融和海水热膨胀均伴随加速度变化。这些研究成果不仅极大地提升了对当前海平面变化的认识,而且有助于约束对未来海平面上升的预测。最后,讨论了海平面变化成因研究中面临的困难与挑战:①在局部尺度上,使用观测数据尚不能完全揭示海平面长期趋势变化成因;②2016年后,全球平均海平面平衡方程的闭合差显著增大。

Revealing the cause of global mean sea level(GMSL)rise helps to advance the knowledge of current climate change,and make adaptive planning.Space geodesy technique along with Argo float greatly improves the investigation of the cause of sea level rise on global and regional scales.These observations serve as important supplements to model output that usually fail to capture long-term trend,in addition to providing independent verifications,they also help to understand the drivers of sea level change on long-term and interannual scales.This paper reviews the achievements and progresses in the cause of sea level change,with a particular focus on discussing the contributions of mass variations over global land area.Observations suggests that,over recent two decades,65%GMSL rise is caused by ocean mass increase due to mass loss in polar ice sheet and mountain glacier,and land hydrology.The remaining GMSL rise is induced by ocean thermal expansion.Given that global warming is expected to continue,both ice mass loss and ocean thermal expansion are associated with acceleration,which results in accelerated GMSL rise.These results have important implications for understanding climate change and projecting future GMSL rise.Except for presenting the major achievements,we also highlight some challenges that confront the study of the cause of GMSL rise,for example:①Observations are not able to close the sea level budget at local scales.②The discrepancy of GMSL budget increases significantly after 2016.