Sea level change in China Coast shows a fluctuant ascending trend. During last 50 years, coastal sea level of China is as a whole on trend of fluctuant ascending, the ascending rate of which is different from time to time. In 1980–2017, the sea level rise rate is 3.3 mm/yr on average. Sea level change along China coast presents remarkable regional characteristics. The most obvious rise is on the coasts of Tianjin, Shandong, Jiangsu and Hainan, followed by the coasts of Liaoning, Shanghai, Zhejiang, Fujian and Guangxi, with the slowest rise in coastal areas of Hebei. Compared with multi-year average, sea level of the Pearl River estuary and the western Hainan coast increased most greatly, with a range of 120mm. Sea level rise in China Coast presents prominent inter-annual variation and inter-decadal variation characteristics. And the oscillation of 4–7yr is most prominent in South China Sea and East China Sea, whose amplitude is close to 1.1cm. Sea level along coastal regions of China takes on strong seasonal variation. Seasonal sea level change is larger in the north than in the south, and annual variation decreases from the north to the south. The lowest lunar-mean sea levels are usually in winter and spring, while the highest levels are usually in summer and autumn. From north to south, highest lunar-mean occurs from July to October, with a difference of nearly 3 months, and annual sea level variation varies from 60cm to 20–30cm correspondingly.
Under the background of global warming, sea level change has become an important indicator of global climate change. Sea level changes represent an integration of many aspects of climate change, and thus occur over a broad range of temporal and spatial scales. The primary contributors to sea level change are the expansion of the ocean as it warms and the transfer of water currently stored on land, particularly from glaciers and ice sheets (IPCC, 2013; IPCC, 2007; Nerem et al., 2006; Church et al., 2011). According to the IPCC Fifth Assessment Report (IPCC, 2013), the global average sea level rise rate is 1.7mm/yr during 1901–2010, while the rates of increase from 1971 to 2010 and from 1993 to 2010 are 2.0 mm/yr and 3.2 mm/yr, respectively.
