Preprints
https://doi.org/10.5194/egusphere-2024-1261
https://doi.org/10.5194/egusphere-2024-1261
07 May 2024
 | 07 May 2024

Assessment of the southern polar and subpolar warming in the PMIP4 Last Interglacial simulations using paleoclimate data syntheses

Qinggang Gao, Emilie Capron, Louise C. Sime, Rachael H. Rhodes, Rahul Sivankutty, Xu Zhang, Bette L. Otto-Bliesner, and Martin Werner

Abstract. Given relatively abundant paleo proxies, the study of the Last Interglacial (LIG, ~129-116 thousand years ago, ka) is valuable to understanding natural variability and feedback in a warmer-than-preindustrial climate. The Paleoclimate Modelling Intercomparison Project Phase 4 (PMIP4) coordinated LIG model simulations which focus on 127 ka. Here we evaluate 12 PMIP4 127-ka Tier 1 model simulations against four recent paleoclimate syntheses of LIG sea and air temperatures and sea ice concentrations. The four syntheses include 99 reconstructions and show considerable variations, some but not all of which are attributable to the different sites included in each synthesis. All syntheses support the presence of a warmer Southern Ocean, with reduced sea ice, and a warmer Antarctica at 127 ka compared to the preindustrial. The PMIP4 127-ka Tier 1 simulations, forced solely by orbital parameters and greenhouse gas concentrations, do not capture the magnitude of this warming. Here we follow up on previous work that suggests the importance of preceding deglaciation meltwater release into the North Atlantic. We run a 3000-year 128-ka simulation using HadCM3 with a 0.25 Sv North Atlantic freshwater hosing, which approximates the PMIP4 127-ka Tier 2 H11 (Heinrich event 11) simulation. The hosed 128-ka HadCM3 simulation captures much of the warming and sea ice loss shown in the four data syntheses at 127 ka relative to preindustrial: south of 40° S, modelled annual sea surface temperature (SST) rises by 1.3±0.6 °C, while reconstructed average anomalies range from 2.2 °C to 2.7 °C; modelled summer SST increases by 1.1±0.7 °C, close to 1.2–2.2 °C reconstructed average anomalies; September sea ice area (SIA) reduces by 40 %, similar to reconstructed 40 % reduction of sea ice concentration (SIC); over the Antarctic ice sheet, modelled annual surface air temperature (SAT) increases by 2.6±0.4 °C, even larger than reconstructed average anomalies 2.2 °C. Our results suggest that the impacts of deglaciation ice sheet meltwater need to be considered to simulate the Southern Ocean and Antarctic changes at 127 ka.

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Qinggang Gao, Emilie Capron, Louise C. Sime, Rachael H. Rhodes, Rahul Sivankutty, Xu Zhang, Bette L. Otto-Bliesner, and Martin Werner

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-2024-1261', Anonymous Referee #1, 24 May 2024
  • RC2: 'Comment on egusphere-2024-1261', Anonymous Referee #2, 05 Jun 2024
  • RC3: 'Comment on egusphere-2024-1261', Anonymous Referee #3, 15 Jun 2024
Qinggang Gao, Emilie Capron, Louise C. Sime, Rachael H. Rhodes, Rahul Sivankutty, Xu Zhang, Bette L. Otto-Bliesner, and Martin Werner

Data sets

The four paleoclimate data syntheses Qinggang Gao, Emilie Capron, Louise C. Sime, Rachael H. Rhodes, Rahul Sivankutty, Xu Zhang, Bette L. Otto-Bliesner, and Martin Werner https://doi.org/10.5281/zenodo.11079974

Qinggang Gao, Emilie Capron, Louise C. Sime, Rachael H. Rhodes, Rahul Sivankutty, Xu Zhang, Bette L. Otto-Bliesner, and Martin Werner

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Short summary
Marine sediment and ice core records suggest a warmer Southern Ocean and Antarctica at the early last interglacial, ~127 thousand years ago. However, when only forced by orbital parameters and greenhouse gas concentrations during that period, state-of-the-art climate models do not reproduce the magnitude of warming. Here we show that much of the warming at southern mid-to-high latitudes can be reproduced by a UK climate model HadCM3 with a 3000-year freshwater forcing over the North Atlantic.