27 Jul 2023
 | 27 Jul 2023

Disentangling the drivers of future Antarctic ice loss with a historically-calibrated ice-sheet model

Violaine Coulon, Ann Kristin Klose, Christoph Kittel, Tamsin Edwards, Fiona Turner, Ricarda Winkelmann, and Frank Pattyn

Abstract. We use an observationally-calibrated ice-sheet model to investigate the future trajectory of the Antarctic ice sheet related to uncertainties in the future balance between sub-shelf melting and ice discharge on the one hand, and the surface mass balance on the other. Our ensemble of simulations, forced by a panel of CMIP6 climate models, suggests that the ocean will be the primary driver of short-term Antarctic mass loss, initiating ice loss in West Antarctica already during this century. The atmosphere initially plays a mitigating role through increased snowfall, leading to an Antarctic contribution to global mean sea-level rise by 2100 of 6 (-8 to 15) cm under a low-emission scenario and 5.5 (-10 to 16) cm under a very high-emission scenario. However, under the very high-emission pathway, the influence of the atmosphere shifts beyond the end of the century, becoming an amplifying driver of mass loss as the ice sheet's surface mass balance decreases. We show that this transition occurs when Antarctic near-surface warming exceeds a critical threshold of +7.5 °C, at which the increase in surface runoff outweighs the increase in snow accumulation, a signal that is amplified by the melt–elevation feedback. Therefore, under the very high-emission scenario, oceanic and atmospheric drivers are projected to result in a complete collapse of the West Antarctic ice sheet along with significant grounding-line retreat in the marine basins of the East Antarctic ice sheet, leading to a median global mean sea-level rise of 2.75 (6.95) m by 2300 (3000). Under a more sustainable socio-economic pathway, we find that the Antarctic ice sheet may still contribute to a median global mean sea-level rise of 0.62 (1.85) m by 2300 (3000). However, the rate of sea-level rise is significantly reduced as mass loss is likely to remain confined to the Amundsen Sea Embayment, where present-day climate conditions seem sufficient to commit to a continuous retreat of Thwaites Glacier.

Violaine Coulon et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-1532', Nicholas Golledge, 18 Aug 2023
  • RC2: 'Comment on egusphere-2023-1532', Daniel Martin, 20 Sep 2023

Violaine Coulon et al.

Violaine Coulon et al.


Total article views: 482 (including HTML, PDF, and XML)
HTML PDF XML Total Supplement BibTeX EndNote
322 151 9 482 29 8 3
  • HTML: 322
  • PDF: 151
  • XML: 9
  • Total: 482
  • Supplement: 29
  • BibTeX: 8
  • EndNote: 3
Views and downloads (calculated since 27 Jul 2023)
Cumulative views and downloads (calculated since 27 Jul 2023)

Viewed (geographical distribution)

Total article views: 470 (including HTML, PDF, and XML) Thereof 470 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
Latest update: 03 Oct 2023
Short summary
We present new projections of the evolution of the Antarctic ice sheet until the end of the millennium, calibrated with observations. We show that the ocean will be the main trigger of future ice loss. As temperatures continue to rise, the atmosphere's role may shift from mitigating to amplifying Antarctic mass loss already by the end of the century. For high-emission scenarios, this may lead to substantial sea-level rise. Adopting sustainable practices would however reduce the rate of ice loss.