Coastal Sea level rise around the China Seas

Abstract:

We analyze the sea level rise along the Bohai Sea, the Yellow Sea, the East China Sea, and the South China Sea (the “China Seas”) coastline using 25 tide gauge records beginning with Macau in 1925, but with most starting during the 1950s and 60s. The main problem in estimating sea level rise for the period is the lack of vertical land movement (VLM) data for the tide gauge stations. We estimated VLM using satellite altimetry covering the 18 stations with records spanning 1993–2016. The results show that many tide gauge stations, typically in cities, have undergone significant subsidence due to groundwater extraction. After removing the VLM from tide gauge records, the 1993–2016 sea level rise rate is 3.2 ± 1.1 mm/yr, and 2.9 ± 0.8 mm/yr over the longer 1980–2016 period. We estimate the steric sea level contribution to be up to 0.9 ± 0.3 mm/yr, and contributions from ice mass loss from glaciers and ice sheets of up to 1.1 ± 0.1 mm/yr over the last 60 years. Contributions from VLM range between −4.5 ± 1.0 mm/yr and 1.4 ± 1.3 mm/yr across the stations. Projections of coastal sea level probability distributions under future climate scenarios show that the steric factor is the main contributor under both the RCP 4.5 and High-end RCP 8.5 scenarios except in the upper tails under High-end RCP 8.5 when the Antarctic ice sheet makes the greatest contribution. By 2100 we expect median coastal sea level rises at the stations of 48–61 cm under RCP 4.5, and 84–99 cm under High-end RCP 8.5 scenario.