Projections of Precipitation and Temperatures in Greenland and the Impact of Spatially Uniform Anomalies on the Evolution of the Ice Sheet

Abstract. Long-term simulations of the Greenland ice sheet (GrIS) often rely on parameterisation schemes for the precipitation rates or assume spatially and temporally uniform temperature and precipitation anomalies over long time scales. However, there is no a priori reason to assume spatially and temporally uniform sensitivities across the whole GrIS. Additionally, parameters are often based on older generations of climate models and it is often assumed that precipitation increases with the standard value of circa 7 %/K based on the Clausius-Clapeyron relation. Here, we give an update on the commonly used parameters used for long-term modelling of the Greenland ice sheet, based on the output of the latest generation of coupled Earth system models (CMIP6), using the historical time period and four different future emission scenarios. We show that the precipitation sensitivities in Greenland have a strong spatial dependence, with values ranging from 0 %/K in southern Greenland up to 15 %/K in northeastern Greenland relative to the global mean temperature (GMT) in the CMIP6 ensemble mean. Additionally, we show that the annual mean temperatures in Greenland increase between 1.29 and 1.53 times faster than the GMT, with northern Greenland warming up to two times faster than southern Greenland in all emission scenarios. However, we also show that there is a considerable spread in the model responses. Finally, we use the state-of-the-art ice sheet model PISM to show that assuming spatially uniform temperature and precipitation anomalies leads to substantial overestimation of ice loss in the long-term behaviour of the GrIS.