Brief communication: CESM2 climate forcing (1950–2014) yields realistic Greenland ice sheet surface mass balance | CU Experts

Abstract. We present a reconstruction of historical (1950–2014) surface mass balance (SMB) of the Greenland ice sheet (GrIS) using a high-resolution regional climate model (RACMO2; ~ 11 km) to dynamically downscale the climate of the Community Earth System Model version 2 (CESM2; ~ 111 km). After further statistical downscaling to 1 km spatial resolution, evaluation using in situ SMB measurements and remotely sensed GrIS mass change shows good agreement, including the recently observed acceleration in surface mass loss (2003–2014). Comparison with an ensemble of eight previously conducted RACMO2 simulations forced by climate reanalysis demonstrates that the current product accurately reproduces the long term average and inter-annual variability of individual SMB components, and captures the recent increase in meltwater runoff that accelerated GrIS mass loss. This means that, for the first time, an Earth System Model (CESM2), without assimilating observations, can be used to reconstruct historical GrIS SMB and the mass loss acceleration that started in the 1990s. This paves the way for attribution studies of future GrIS mass loss projections and contribution to sea level rise.;

Noël B; van Kampenhout L; van de Berg WJ; Lenaerts JTM; Wouters B; van den Broeke MR

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