Planet Earth is a complex system made up of several components that interact across a range of spatial and temporal scales: the Earth’s interior, continental surfaces, the fluid envelopes (atmosphere and ocean), the biosphere and the cryosphere. Given the inherent complexity of this system, understanding its evolution and quantifying its current state require a twofold approach: on the one hand, the collection of data, and on the other, modelling.

– Gérard Mégie (1946-2004), founder of the IPSL.

Born in the mid-1990s from the vision of Gérard Mégie, a remarkable scientist and atmospheric physicist, the Institut Pierre-Simon Laplace (IPSL) has served as a hub for climate-observation and modelling communities in the Paris region. Over the past three decades, IPSL has become a leading reference point, both within the French scientific community and internationally, notably through its contributions to the work of the IPCC.

This year, on 11 and 12 December 2025, alongside the tenth anniversary of the historic Paris Agreement, the research federation* will celebrate its anniversary.
Two days devoted to the major milestones in the Institute’s history and to today’s challenges: from the earliest coupled numerical models to pioneering scientific field campaigns, from the rise of open science to the disruptions introduced by artificial intelligence.

The event begins with a panel discussion featuring the historian of science Matthias Cléry, together with IPSL Director Sophie Godin-Beekmann and two of her predecessors, Robert Vautard and Jean Jouzel. This will be followed by contributions from internationally renowned experts, including Susan Solomon, Professor of Environmental Studies at the Massachusetts Institute of Technology and a pioneer in atmospheric research; Laurence Tubiana and Paul Watkinson, architects of the Paris Agreement adopted by 195 countries in 2015; David Chavalarias, Director of the Institut des Systèmes Complexes de Paris; and journalists Audrey Garric (Le Monde) and Thomas Wagner (Bon Pote).

The event will also provide a chance to look back on recent developments at the Centre for Earth Observation, represented by Martial Haeffelin, Valérie Gros, Vincent Thieu and Gilles Reverdin, at the Modelling Centre, with contributions from Julie Deshayes, Marie-Alice Foujols and Pascale Braconnot and at the ESPRI computing and data centre.

Interdisciplinary by design and a driver of collaboration since its founding, the IPSL continues to pursue its mission of engaging with the humanities and social sciences, as well as with society at large — from policymakers to the media and the general public. Its work places particular emphasis on actual issues, including the attribution of extreme events to climate change, the links between air pollution and climate, the need to reassess and adapt research practices to reduce science’s carbon footprint, the importance of improving communication to counter climate misinformation and the vital role of education through the IPSL Climate Graduate School.

Two days rich in insights and exchanges, combining reflections on the past with discussions on the future of the issues that have shaped — and continue to shape — climate and environmental science.

*officially an “Unité d’Aide à la Recherche” (UAR) since 2024.

Find out more

Event Programme 

The gathering on 11–12 December 2025 provides a unique opportunity to reflect on thirty years of climate research at the IPSL and to explore the current challenges that climate science faces in society. You can view the full two-day programme here.

« 30 Years of Climate Research at IPSL »

The short-film series