IPCC气候情景下全球海平面长期趋势变化

Long term trends in global sea level under IPCC SRES A2 scenario

利用CCSM3(Community Climate System Model version 3)气候系统模式模拟20世纪海平面变化,在IPCC SRES A2(IPCC,2001)情景假设下预测21世纪全球海平面长期趋势变化。模拟显示20世纪海平面上升约4.0cm,且存在0.004 8mm/a2的加速度,这个结果仅为热盐比容的贡献。在A2情景假设下,21世纪海平面上升存在很大的区域特征,呈纬向带状分布;总体上北冰洋上升大,南大洋高纬度海区上升小,大西洋上升值比太平洋的大;整个21世纪全球平均比容海平面上升了约30cm,且呈加速上升的趋势。同时发现,中深层水温度和盐度变化对区域比容海平面变化具有重要贡献。北太平洋增暖主要集中在上层700m以内,而北大西洋的增暖可达2 500m的深度,南大洋南极绕极流海区热盐变化则是发生在整个深度。

Based on CCSM3（Community Climate System Model version 3） model,the long-term sea level trends of global ocean in the 20th and 21st century under IPCC SRES A2 scenario（IPCC,2001） are analyzed in this paper.The result shows that global sea level rises about 4.0 cm during 20th century through steric expansion,with an acceleration of 0.004 8 mm/a2;eustatic changes are not included in this simulation.CCSM3 simulation also shows that in the 21st century sea level will rise in acceleration;the global sea level will rise 30 cm during the whole century through steric expansion.The vertical distribution of thermosteric and halosteric anomalies that contribute to sea level change is very different between ocean basins.Significant warming of the North Atlantic Ocean can extend to 2 500 m depth,while the salinity change partially counteracts sea level rise due to this warming.The steric anomalies in the Pacific Ocean occur mainly in the upper 700 m.In the Southern Ocean,steric change can extend to the entire water column.