Interpreting Century-To-Decadal Scale Sea-Level Records From Greenland

In this paper, we interpret high-resolution sea-level observations collected at two localities on the west coast of Greenland (Sisimuit: 66.465°N, -53.606°W and Aasiaat: 68.683°N, -52.799°W), and one in south of Greenland (Nanortalik: 60.073°N, -44.988°W). The changes in relative sea- level are reconstructed from salt marsh deposits using a diatom-based transfer function approach. The resulting trend in relative sea-level change recorded in the salt marshes is a combination of glacial isostatic adjustment associated past mass changes of the Greenland and Laurentide ice sheets , steric ocean changes and contemporary mass variations of the Greenland Ice Sheet (GrIS). We attempt to determine which of these processes contribute significantly to the observed sea-level change. We have reconstructed the recent (1866-2005) surface mass balance history of the GrIS on a 5 x 5 km grid using a runoff-retention model based on the positive degree-day method. The model is forced with gridded datasets of temperature and precipitation. Our results highlight that the ice sheet has the potential to react significantly to interannual climatic changes, and puts the recent, dramatic mass losses into context. During 1923-1933, we model an average annual mass loss of -60Gt/yr compared to -62 Gt/yr in 1995-2005, indicating that current surface mass balance changes are not entirely exceptional. In order to interpret the three ~500 yr sea-level records from the SW sector of the GrIS, we compute the sea-level response to: (i) our SMB model, (ii) ice dynamic mass loss due to draw-down of ice in the Jakobshavn drainage area, and (iii) temperature and salinity changes of the adjacent ocean water.