Missions

As part of the LSCE MERMAID team, which is involved in the development and application of the IPSL model for aspects of ocean-atmosphere coupling and between climate and biogeochemical cycles, the successful candidate will be in charge of analyses of vegetation tipping points related to the meridional circulation of the North Atlantic Ocean or to vegetation dynamics. The results of simulations of the last 6,000 years, extended to the present and future with the IPSL model, will be used for the analyses. The credibility of the results obtained will be assessed in relation to palaeoclimatic reconstructions. Sensitivity tests to the state of the vegetation cover and the thermohaline circulation will be performed to investigate the mechanisms and uncertainties associated with the occurrence of tipping points. The aim of this work is to develop early warning indicators for the occurrence of tipping points and to gain a better understanding of the interactions between climate-related and vegetation-related tipping points in terms of vegetation cover. The two main regions of interest for this work are the Sahel-Sahara transition and the boreal forests of Europe and Eurasia. The work will be carried out in close collaboration with the IPSL-LOCEAN (Paris) and EPOC (Bordeaux) teams involved in the project, in order to provide information on the long term and on decadal to multi-decadal variability that cannot be fully studied using simulations or observations of the current climate. Particular attention will be paid to the transferability of the criteria obtained to the future climate, which will be dominated by human activities.

Activités

• Analysis of the evolution, variability and tipping points of vegetation in the Sahel-Sahara and Northern Europe in transient simulations over the last 6,000 years using the IPSL climate-dynamic vegetation model.
• Estimation of the vulnerability of the vegetation cover according to the state of the vegetation or soil moisture based on drought or temperature indices.
• Design of additional simulations to verify hypotheses on the mechanisms favouring vegetation tipping points.
• Comparison of the results of the simulations with the palaeoclimatic data available for the Holocene. Publication of one or more articles on the topic of the post-doc and in collaboration with the other partners of the projects for the synthesis of the work packages or cross-referenced analyses between the past, present and future.

Compétences

• Have a thesis in the field of climate modelling, climate variability or interactions between climate and biogeochemical cycles (with an interest in vegetation).
• Demonstrate an ability to work in a team and at the interface between several people and types of approach.
• Demonstrate the ability to put forward proposals, creativity, autonomy and the ability to communicate and report.
•Expertise in climate modelling and simulations, or expertise in analysing large datasets and the ability to work in a national computing centre.
• Ability to write scientific papers and present results to different audiences
• Fluency in English (level 2) and, if possible, some knowledge of French.

Contexte de travail

The 2-year post-doctoral position is part of the European TIPESM project, in which IPSL is a partner. This project investigates climate tipping points using climate simulations of past and future climates. The successful candidate will be based at the Laboratoire des sciences du climat et de l'environnement and will work under the supervision of Pascale Braconnot and Olivier Marti in a team developing the IPSL climate model and using it for long-term transient simulations over the last 6000 years. The proposed topic and, more generally, the TIPESM project are part of an international effort to study tipping points and high-impact climate events. There are still many uncertainties surrounding abrupt events, making it difficult to account for them in risk studies. It is also important to determine whether the climate models used for climate projections correctly represent certain threshold behaviours, and to better understand the links between events related to climatic factors or resulting from thresholds in ecosystem functioning. In this context, the proposed work will focus on aspects related to vegetation dynamics. The results of the project will feed into the synthesis on this topic led by the World Climate Research Programme Lighthouse Activity "Safe Landing Climate" and the authors of Chapter 8 on tipping points in the 7th Assessment Report of the IPCC Group 1.

The IPSL, a partner in the TIPESM project, is a research support unit comprising 10 laboratories in the Ile-de-France region. In particular, the modelling centre brings together modelling efforts for the study of climate, its variability and its changes. It coordinates the development of the IPSL climate model. The Climate and Environmental Sciences Laboratory is located on the Paris Saclay campus. It is a joint laboratory of the CNRS, the CEA and the UVSQ. At CNRS level, its scientific activities come under the CNRS Institut des sciences de l'univers. The LSCE is home to a climate and cycles modelling theme that brings together 4 teams, including the MERMAID team. This theme contributes to the IPSL's modelling and develops activities related to model development, the study of climate and paleoclimates, and the links between climate and biogeochemical cycles (aerosols, chemistry, carbon cycle, etc.), allowing the study of the many interactions in the climate system and the development of research which are relevant to issues related to mitigation and adaptation to climate change. Le thème regroupe également des spécialistes de méthodes statistiques s'intéressant à la détection et l'attribution des changements climatiques, ainsi qu'au extrêmes climatiques et événements rares. Les activités de ce thème bénéficient également des nombreuses interactions avec les équipes des autres thèmes, que ce soit pour les aspects concernant les comparaisons entre modèles et données pour les études des paléoclimats ou des cycles biogéochimiques.

Informations complémentaires

The dead line for application is June 4 2025.