Improved Understanding of Multicentury Greenland Ice Sheet Response to
Strong Warming in the Coupled CESM2‐CISM2 with Regional Grid Refinement
Abstract
The simulation of ice sheet-climate interaction such as surface mass
balance fluxes are sensitive to model grid resolution. Here we simulate
the multicentury evolution of the Greenland Ice Sheet (GrIS) and its
interaction with the climate using the Community Earth System Model
version 2.2 (CESM2.2) including an interactive GrIS component (the
Community Ice Sheet Model v2.1 [CISM2.1]) under an idealized warming
scenario (atmospheric CO2 increases by 1% yr−1 until quadrupling the
pre-industrial level and then is held fixed). A variable-resolution (VR)
grid with 1/4◦ regional refinement over broader Arctic and 1◦ resolution
elsewhere is applied to the atmosphere and land components, and the
results are compared to conventional 1◦ lat-lon grid simulations to
investigate the impact of grid refinement. An acceleration of GrIS mass
loss is found at around year 110, caused by rapidly increasing surface
melt as the ablation area expands with associated albedo feedback and
increased turbulent fluxes. Compared to the 1◦ runs, the VR run features
slower melt increase, especially over Western and Northern Greenland,
which slope gently towards the peripheries. This difference pattern
originates primarily from the weaker albedo feedback in the VR run,
complemented by its smaller cloud longwave radiation. The steeper VR
Greenland surface topography favors slower ablation zone expansion, thus
leading to its weaker albedo feedback. The sea level rise contribution
from the GrIS in the VR run is 53 mm by year 150 and 831 mm by year 350,
approximately 40% and 20% smaller than the 1◦ runs, respectively.