Sea level projections using ice sheet model based on RCP scenarios at David Glacier, East Antarctica

Abstract

A net ice mass change contributing to the change in global sea level is mainly estimated from the ice mass discharge at grounding line, and the mass gain or loss from surface mass balance (SMB), which is calculated as precipitation minus evaporation. In addition, basal mass balance and frontal mass balance can be also considered. The ice mass discharge can be calculated by ice sheet model, while SMB can be produced by couple global climate model (CGCM) with large discrepancies among models due to uncertainties in physical parameterizations. Here, we conduct a series of future projection experiments using Ice Sheet System Model (ISSM) forced with RCP-based SMB from 19 CMIP5 CGCMs with total 177 ensemble members for investigating the contribution of ice mass change at David Glacier, East Antarctica to the global sea level upto 2100 (~2300). Recently, an additional ice radar survey was performed at study area and merged with previous dataset to produce a new bed geometry, which reveals a sharp subglacial ridge above sea level stabilizing an ice flow. Therefore, we only focus on the effect of change in SMB on the sea level change. A gradual increase in ice volume related with CGCMs’ SMB increase is shown in most ice sheet model projections, however, projections forced by GISS-E2-R and IPSL-CMA5A-MR SMB with RCP8.5 scenario display an increase in sea level equivalent for 0.72 mm and 0.31 mm respectively from 1950 to 2100. A total mean of sea level equivalent from 177 ensemble projections is -0.70 mm (sea level decrease) for RCP4.5 and -1.51 mm for RCP8.5 until 2100 year, moreover, RCP8.5 scenario until 2300 projection exhibit sea level decrease of -4.66 mm owing to continuous increase in SMB at study area.