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Abstract Coupled global climate models (GCMs) generally fail to reproduce the observed sea‐surface temperature (SST) trend pattern since the 1980s. The model‐observation discrepancies may arise in part from the lack of realistic Antarctic ice‐sheet meltwater input in GCMs. Here we employ two sets of CESM1‐CAM5 simulations forced by anomalous Antarctic meltwater fluxes over 1980–2013 and through the 21st century. Both show a reduced global warming rate and an SST trend pattern that better resembles observations. The meltwater drives surface cooling in the Southern Ocean and the tropical southeast Pacific, in turn increasing low‐cloud cover and driving radiative feedbacks to become more stabilizing (corresponding to a lower effective climate sensitivity). These feedback changes can contribute as substantially as ocean heat uptake efficiency changes in reducing the global warming rate. Accurately projecting historical and future warming thus requires improved representation of Antarctic meltwater and its impacts.
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From the Surface to the Stratosphere: Large‐Scale Atmospheric Response to Antarctic Meltwater
Abstract The ocean response to Antarctic Ice Sheet (AIS) mass loss has been extensively studied using numerical models, but less attention has been given to the atmosphere. We examine the global atmospheric response to AIS meltwater in an ensemble of experiments performed using two fully coupled climate models under a pre‐industrial climate. In response to AIS meltwater, the experiments yield cooling from the surface to the tropopause over the subpolar Southern Ocean, warming in the Southern Hemisphere polar stratosphere, and cooling in the upper tropical troposphere. Positive feedbacks, initiated by disrupted ocean‐atmosphere heat exchange, result in a change in the top‐of‐atmosphere radiative balance caused primarily through surface and near‐surface albedo changes. Changes in the atmospheric thermal structure alter the jet streams aloft. The results highlight the global influence of AIS melting on the climate system and the potential for impacts on mid‐latitude climate patterns and delayed regional warming signals.
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- PAR ID:
- 10554324
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Geophysical Research Letters
- Volume:
- 51
- Issue:
- 21
- ISSN:
- 0094-8276
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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