IEDA
Project Information
Collaborative Research: Assessing the Global Climate Response to Melting of the Antarctic Ice Sheet
Short Title:
Role of Antarctic meltwater oceanic discharge in warming scenarios
Start Date:
2015-09-01
End Date:
2018-08-31
Description/Abstract
A great deal of uncertainty remains over how changes in high-latitude freshwater forcing will impact the stability of global ocean circulation, and in particular the strength of the Atlantic Meridional Overturning Circulation (AMOC) in the next 100-300 years, especially in realistic models. Indeed, it is still not understood whether increased Southern Ocean freshwater forcing will act to intensify the AMOC and warm the Northern Hemisphere or weaken it and trigger a cooling. The requirement to accurately assess climate sensitivity to freshwater forcing is heightened by increasing evidence that the marine-based West Antarctic Ice Sheet (WAIS) is vulnerable to rapid retreat and collapse on multidecadal-to-centennial timescales. Observations collected over the last 30 years indicate that WAIS is losing ice at an accelerated rate and may signal that the ice sheet has already begun a rapid and irreversible collapse. In addition, future simulations of the Antarctic ice sheet by members of our Project Team show the potential for far more rapid Antarctic ice sheet retreat in the future than previously simulated, suggesting that the discharge of enormous fluxes of icebergs and freshwater to the Southern Ocean should be considered a possibility in the near-future. Here, we performed a suite of coupled numerical climate model simulations to more accurately determine the sensitivity of global ocean circulation to freshwater and iceberg discharge from the Antarctic Ice Sheet (AIS) in the future under IPCC RCP scenarios 4.5 and 8.5. In our model, the input of freshwater and ice was provided by a dynamic ice sheet-shelf model that predicts a full collapse of the WAIS in the next ~100 years. Significantly, we find that accounting for Antarctic discharge raises subsurface ocean temperatures by >1°C at the ice sheet grounding line, relative to model simulations that are unable to capture this discharge. In contrast, we find that the increased meltwater causes a dramatic expansion of sea ice and a 2° - 10°C cooling of the surface air and surface ocean temperatures over the Southern Ocean that would have the potential to stabilize/reduce projected future ice sheet melt rates. Our work thus highlights that the future stability of the Antarctic ice sheet will likely be governed by whether any surface cooling can counteract any increased rates of subsurface melt.
Personnel
Person Role
Pollard, David Investigator and contact
Condron, Alan Investigator
DeConto, Robert Investigator
Funding
Antarctic Integrated System Science Award # 1443394
Antarctic Integrated System Science Award # 1443347
AMD - DIF Record(s)
Data Management Plan
None in the Database
Publications
  1. DeConto, R.M. and D. Pollard. 2016. Contribution of Antarctica to past and future sea-level rise. Nature, 531, 591-597. (doi:10.1038/nature17145)
  2. Pollard, D., R.M. DeConto and R.B. Alley. 2018. A continuum model (PSUMEL1) of ice mélange and its role during retreat of the Antarctic Ice Sheet. Geosci. Model Devel., 11, 5149-5172. (doi:10.5194/gmd-11-5149-2018)
  3. Sadai S, Condron A, DeConto R,M., and Pollard D. (2020). Future climate response to Antarctic Ice Sheet melt caused by anthropogenic warming. Science Advances, Vol. 6, eaaz1169 (doi:10.1126/sciadv.aaz1169)
  4. DeConto R.M., Pollard, D., Alley, R.B., Velicogna, I., Gasson, E., Gomez, N., Sadai. S., Condron, A., Gilford, D.M., Ashe, E., L., Li, D., and Kopp, R.E. (2021). The Paris Climate Agreement and future sea-level rise from Antarctica, Nature, 593, 83–89. (doi:10.1038/s41586-021-03427-0)
  5. Ashley, K. E., McKay, R., Etourneau, J., Jimenez-Espejo, F. J., Condron, A., Albot, A., Crosta, X., Riesselman, C., Seki, O., Massé, G., Golledge, N. R., Gasson, E., Lowry, D. P., Barrand, N. E., Johnson, K., Bertler, N., Escutia, C., Dunbar, R., and Bendle, J. A., (2021). Mid-Holocene Antarctic sea-ice increase driven by marine ice sheet retreat, Climate of the Past, 17, 1–19, (doi:10.5194/cp-17-1-2021)
  6. Ashley, K. E., Bendle, J. A., McKay, R., Etourneau, J., Jimenez-Espejo, F. J., Condron, A., … Dunbar, R. (2020). Mid-Holocene Antarctic sea-ice increase driven by marine ice sheet retreat. (doi:10.5194/cp-2020-3)

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