Description of the program
IPCC scenarios (AR6 WG1) depict, for the end of this century, atmospheric CO2 concentrations (pCO2) ranging from 400 to 1200ppm1 (Summary for policy makers AR6 WG1). Therefore, studying past periods of climates with high atmospheric pCO2 is pivotal.
Over the past million years, Earth’s climate has been dominated by glacial-interglacial cycles associated with CO2 variations evolving in a very narrow window (180-280 ppm)2 (Parrenin et al., Clim. Past, 2007). It is therefore necessary to look beyond the Quaternary to find higher values3 (James Rae, EPSL,model / data mismatch, as well as the interaction between the different components of the climate system in a warm high CO2 world.
II. Investigating and advertising climate future evolution at centennial to millennium scales.
Following the first two weeks with the students, lecturers and mentors we will expand the group with additional experts in the field as well as expert communicators and spend three days to bridge and apply the knowledge acquired during the first two weeks of the workshop.
These final three days will be devoted to discussing the different possibilities for the future evolution of our planet at scales of centuries to millennia.
The crucial questions for the future climate evolution at secular scales are, therefore, to explore at which pCO2 level, cryosphere configurations and ocean circulations, the climate will equilibrate after the large emissions of anthropic GHG9 10 (Lenton et al., Clim. Dyn., 2006; Berger, Loutre et al., Science, 2002).
In this second part of the workshop, we want to explore which new climate equilibrium will result from the anthropic perturbation. Depending on the transient scenario our planet will experience during the perturbation, we may reach different equilibria. A second important topic of the workshop will be to advertise these issues.
pCO2 evolution over millions of years (left), hundreds of kyrs (center) and secular time-scale (right), Rae et al., EPSL, 2021.
pCO2 evolution over millions of years (left), hundreds of kyrs (center) and secular time-scale (right), Rae et al., EPSL, 2021
The first week will be devoted to lectures and discussions with examples from Cenozoic warm greenhouse climates based on both general circulation models and empirical reconstructions. We will focus on the mid-Pliocene, mid-Miocene and early Eocene, giving the students an overview of the strengths and weaknesses of simulations when compared to data synthesis for each period. We will also analyse limitations associated with uncertainties on reconstruction and dating.
After this first overview, the second week will be devoted to short presentations on key topics combined with project work in groups:
- A greenhouse gases reconstruction during these warm periods. Invited talks: James Rae (CO2), Peter Hopcroft (CH4).
- Equator-to-pole thermal gradient: a model-data comparison. Invited talks: Julia Tindall, Natalie J. Burls, Daniel Lunt.
- Ocean dynamics versus closing / opening of straits. Invited talk: Zhongshi Zhang, Ning Tan, Gregor Knorr.
- The role of the cryosphere on climate variability for Pliocene and Miocene. Invited talks: Anna Ruth Halberstadt, Aisling Dolan, Petra Langebroek, Robert DeConto.
- The contribution of the continental biosphere including the C3/C4 photosynthetic pathway.
Invited talk: Sarah Feakins.
The students will be divided into 6-8 groups working with 1-2 mentors based on key topics. The project topics will be refined during the first week, with dedicated time during the second week to perform critical analysis before being presented to the larger group. Each group of students will be expected to present their work during the final three days of the workshop to the broader community of scientists present at the workshop.
List of the scientific organizers (6):
§ Gilles Ramstein (LSCE), gilles.ramstein@lsce.ipsl.fr;
§ Kerim Nisancioglu (Universityof Bergen), kerim@uib.no;
§ David S. Battisti (Universityof Washington), battisti@uw.edu;
These teams reflect the different components of climate Earth system: past, present and future.
List of the co-organizers (7):
Florence Colleoni [National Institute of Oceanography, Trieste] or Anna Ruth Halberstadt [University of Texas] (cryosphere), Ricarda Winkelmann [Max Planck Institute of Geoanthropology, Germany] (ice sheet and social impacts), Julia Tindall [University of Leeds] (Pliocene model inter comparison project, MIP, isotope modelling), Daniel Lunt [University of Bristol] (Eocene, MIP), Natalie J. Burls [University of George Mason, USA] (Miocene, MIP), Erin McClymont [University of Durham] or Sindia Sosdian [University of Cardiff] (SST reconstructions) and James Rae [University of St Andrews, Scotland] (pCO2 reconstructions).
Local organizing committee (7):
Gilles Ramstein, Elisabeth Michel, Maxime Tremblin, Mathieu Daëron, Sébastien Nomade, Lucie Laurent (LSCE) Frédéric Fluteau (IPG)
