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Abstract The West Antarctic Ice Sheet (WAIS) may have collapsed during the last interglacial period, between 132,000 and 116,000 years ago. The changes in topography resulting from WAIS collapse would be accompanied by significant changes in Antarctic surface climate, atmospheric circulation, and ocean conditions. Evidence of these changes may be recorded in water-isotope ratios in precipitation archived in the ice. We conduct high-resolution simulations with an isotope-enabled version of the Weather Research and Forecasting Model over Antarctica, with boundary conditions provided by climate-model simulations with both present-day and lowered WAIS topography. The results show that while there is significant spatial variability, WAIS collapse would cause detectable isotopic changes at several locations where ice-core records have been obtained or could be obtained in the future. The most robust signals include elevated δ 18 O at SkyTrain Ice Rise in West Antarctica, and elevated deuterium excess at Hercules Dome in East Antarctica. A combination of records from multiple sites would provide constraints on the timing, rate, and magnitude of past WAIS collapse.
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Linearity of the climate system response to raising and lowering West Antarctic and coastal Antarctic topography
Abstract A hierarchy of general circulation models (GCMs) is used to investigate the linearity of the response of the climate system to changes in Antarctic topography. Experiments were conducted with a GCM with either a slab-ocean or fixed SSTs and sea ice, in which the West Antarctic ice sheet (WAIS) and coastal Antarctic topography was either lowered or raised in an idealizedway. Additional experimentswere conducted with a fully-coupledGCMwith topographic perturbations based on an ice-sheet model in which the WAIS collapses. The response over the continent is the same in all model configurations and is mostly linear. In contrast, the response has substantial non-linear elements over the Southern Ocean that depend on the model configuration due to feedbacks with sea ice, ocean, and clouds. The atmosphere warms near the surface over much of the Southern Ocean and cools in the stratosphere over Antarctica, whether topography is raised or lowered. When topography is lowered, the Southern Ocean surface warming is due to strengthened southward atmospheric heat transport and associated enhanced storminess over the WAIS and the high latitudes of the Southern Ocean. When topography is raised, Southern Ocean warming is more limited, and associated with circulation anomalies. The response in the fully-coupled experiments is generally consistent with the more idealized experiments, but the full-depth ocean warms throughout the water column whether topography is raised or lowered. These results indicate that ice sheet-climate system feedbacks differ depending on whether the Antarctic ice sheet is gaining or losing mass.
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- PAR ID:
- 10414341
- Date Published:
- Journal Name:
- Journal of Climate
- ISSN:
- 0894-8755
- Page Range / eLocation ID:
- 1 to 35
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1175/JCLI-D-22-0416.1
