Abstract
We present climate and surface mass balance (SMB) of the Antarctic ice sheet (AIS) as simulated by the global, coupled ocean–atmosphere–land Community Earth System Model (CESM) with a horizontal resolution of $${\sim }1^\circ$$ in the past, present and future (1850–2100). CESM correctly simulates present-day Antarctic sea ice extent, large-scale atmospheric circulation and near-surface climate, but fails to simulate the recent expansion of Antarctic sea ice. The present-day Antarctic ice sheet SMB equals $$2280 \pm 131$$ $$\mathrm {Gt\,year^{-1}}$$ , which concurs with existing independent estimates of AIS SMB. When forced by two CMIP5 climate change scenarios (high mitigation scenario RCP2.6 and high-emission scenario RCP8.5), CESM projects an increase of Antarctic ice sheet SMB of about 70 $$\mathrm {Gt\,year^{-1}}$$ per degree warming. This increase is driven by enhanced snowfall, which is partially counteracted by more surface melt and runoff along the ice sheet’s edges. This intensifying hydrological cycle is predominantly driven by atmospheric warming, which increases (1) the moisture-carrying capacity of the atmosphere, (2) oceanic source region evaporation, and (3) summer AIS cloud liquid water content.
Highlights
The Antarctic ice sheet (AIS) is the largest body of ice on Earth, with an ice volume equivalent to 58.3 m global mean sea level rise (Vaughan et al 2013)
This paper presents the recent, present-day and future (1850–2100) climate and surface mass balance (SMB) of the Antarctic ice sheet, as simulated by the Community Earth System Model (CESM), version 1.1.2
We evaluated the CESM output using observational datasets, atmospheric reanalyses, and the regional climate model RACMO2 and show that CESM is relatively well able to simulate present-day climate, sea ice cover and large-scale atmospheric circulation of the AIS and its surroundings
Summary
The Antarctic ice sheet (AIS) is the largest body of ice on Earth, with an ice volume equivalent to 58.3 m global mean sea level rise (Vaughan et al 2013). The combination of atmospheric and oceanic warming that has led to recent AIS changes underscore the need for a global coupled modelling framework (atmosphere, sea ice, ocean, and land ice) (Krinner et al 2014), which should include a snow model for simulating a realistic snow albedo, metamorphosis and melt, and with multiple vertical layers, necessary to simulate percolation, refreezing and runoff of meltwater in the snowpack. To address this need, we present output from the ∼1◦ resolution Community Earth System Model (CESM), version 1.1.2.
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