24 May 2023
 | 24 May 2023
Status: this preprint is currently under review for the journal CP.

Resilient Antarctic monsoonal climate prevented ice growth during the Eocene

Michiel Baatsen, Peter Bijl, Anna von der Heydt, Appy Sluijs, and Henk Dijkstra

Abstract. Understanding the extreme greenhouse of the Eocene (56–34Ma ago) is key to anticipate potential future conditions. During the Eocene, the Antarctic continent remained mostly ice-free despite large temperature swings. Seemingly contradictory indications of ice and thriving vegetation complicate modelling efforts to explain the Antarctic Eocene climate. We use global climate model simulations to show that extreme seasonality mostly limited ice growth. Without ice sheets, much of the Antarctic continent saw monsoonal conditions. Perennially mild and wet conditions along Antarctic coastlines support vegetation reconstructions, while extreme seasonality elsewhere promoted intense weathering shown in proxy records. The results can thus explain the coexistence of warm and wet conditions in some regions, while small ice caps could form near the coast. The resilience of the climate regimes seen in these simulations agrees with the longevity of warm Antarctic conditions during the Eocene, but also challenge our view on glacial inception.

Michiel Baatsen 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 cp-2023-36', Anonymous Referee #1, 12 Jul 2023
    • AC1: 'Reply on RC1', Michiel Baatsen, 25 Sep 2023
  • RC2: 'Comment on cp-2023-36', Anonymous Referee #2, 28 Aug 2023
    • AC2: 'Reply on RC2', Michiel Baatsen, 25 Sep 2023

Michiel Baatsen et al.

Michiel Baatsen et al.


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Short summary
This work introduces the possibility and consequences of monsoons on Antarctica in the warm Eocene climate. We suggest that such a monsoonal climate can be important to understand conditions on Antarctica prior to large-scale glaciation. We can explain seemingly contradictory indications of ice and vegetation on the continent through regional variability. In addition, we provide a new mechanism through which most of Antarctica remained ice-free through a wide range of global climatic changes.