Mean relative sea level rise along the coasts of the China Seas from mid-20th to 21st centuries

Abstract

Mean relative sea level (MRSL) rise has caused more frequent flooding in many parts of the world. The MRSL rise varies substantially from place to place. Here we use tide-gauge data and satellite measurements to examine past MRSL trends for the coasts of the China Seas. We then combine climate model output and satellite observations to provide MRSL projections in the 21st century. The MRSL trend based on tide-gauge data shows substantial regional variations, from 1 to 5mm/yr. The vertical land motion (VLM) based on altimetry and tide-gauge (ATG) data indicates large land subsidence at some tide-gauge locations, consistent with the Global Positioning Systems (GPS)-based VLM but different significantly from small uplift estimated by a Glacial Isostatic Adjustment (GIA) model, which suggests other important factors causing the VLM instead of the GIA process. When GPS- or ATG-based VLM estimates are used, the projected MRSL rise between 1986–2005 and 2081–2100 at tide-gauge sites varies from 60 to 130cm under the Representative Concentration Pathway 8.5 (RCP8.5) scenario of the Intergovernmental Panel on Climate Change (IPCC). Our projections are significantly larger than those of IPCC and other literature, as a result of accounting for the land subsidence derived from observations. Steric and dynamic ocean effects and land-ice melt effects are comparable (about 30cm each) and do not vary much over the tide-gauge locations. The VLM effect varies from −10 to 60cm. The projections between 1986–2005 and 2081–2100 under RCP4.5 show a similar spatial distribution to that under RCP8.5, with a smaller amount of rise by 18cm on average for this region.