Preprints
https://doi.org/10.5194/cp-2021-70
https://doi.org/10.5194/cp-2021-70

  21 Jun 2021

21 Jun 2021

Review status: this preprint is currently under review for the journal CP.

An energy budget approach to understand the Arctic warming during the Last Interglacial

Marie Sicard1, Masa Kageyama1, Sylvie Charbit1, Pascale Braconnot1, and Jean-Baptiste Madeleine2 Marie Sicard et al.
  • 1Laboratoire des Sciences du Climat et de l’Environnement, Institut Pierre Simon Laplace, Université Paris-Saclay, 91191 Gif-sur-Yvette Cedex, France
  • 2Laboratoire de Météorologie Dynamique, Institut Pierre Simon Laplace, Sorbonne Université, 75252 Paris Cedex 05, France

Abstract. The Last Interglacial period (129–116 ka BP) is characterized by a strong orbital forcing which leads to a different seasonal and latitudinal distribution of insolation compared to the pre-industrial period. In particular, these changes amplify the seasonality of the insolation in the high latitudes of the northern hemisphere. Here, we investigate the Arctic climate response to this forcing by comparing the CMIP6 lig127k and pi-Control simulations performed with the IPSL-CM6A-LR model. Using an energy budget framework, we analyse the interactions between the atmosphere, ocean, sea ice and continents.

In summer, the insolation anomaly reaches its maximum and causes a near-surface air temperature rise of 3.2 °C over the Arctic region. This warming is primarily due to a strong positive surface downwelling shortwave radiation anomaly over continental surfaces, followed by large heat transfers from the continents back to the atmosphere. The surface layers of the Arctic Ocean also receives more energy, but in smaller quantity than the continents due to a cloud negative feedback. Furthermore, while heat exchanges from the continental surfaces towards the atmosphere are strengthened, the ocean absorbs and stores the heat excess due to a decline in sea ice cover.

However, the maximum near-surface air temperature anomaly does not peak in summer like insolation, but occurs in autumn with a temperature increase of 4.0 °C relative to the pre-industrial period. This strong warming is driven by a positive anomaly of longwave radiations over the Arctic ocean enhanced by a positive cloud feedback. It is also favoured by the summer and autumn Arctic sea ice retreat (−1.9 × 106 and −3.4 × 106 km2 respectively), which exposes the warm oceanic surface and allows heat stored by the ocean in summer and water vapour to be released. This study highlights the crucial role of the sea ice cover variations, the Arctic ocean, as well as changes in polar clouds optical properties on the Last Interglacial Arctic warming.

Marie Sicard et al.

Status: open (until 16 Aug 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on cp-2021-70', Pepijn Bakker, 29 Jun 2021 reply

Marie Sicard et al.

Data sets

IPSL-CM6A-LR model output prepared for CMIP6 Boucher, Olivier; Denvil, Sébastien; Levavasseur, Guillaume; Cozic, Anne; Caubel, Arnaud; Foujols, Marie-Alice; Meurdesoif, Yann; Braconnot, Pascale; Contoux, Camille; Kageyama, Masa; Khodri, Myriam https://doi.org/10.22033/ESGF/CMIP6.5228

Marie Sicard et al.

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Short summary
The Last Interglacial (129–116 ka BP) is characterized by an increased summer insolation over the Arctic region, which leads to a strong temperature rise. The aim of this study is to identify and quantify the main processes and feedbacks causing this Arctic warming. Using the IPSL-CM6A-LR model, we investigate changes in the energy budget relative to the pre-industrial period. We highlight the crucial role of the Arctic sea ice cover, ocean and clouds on the Last Interglacial Arctic warming.