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  Earth system science


Heads: Julien Bouchez and Stéphane Jacquemoud


Earth system science deals with the interactions between the Earth's "spheres" as well as with the impact of human societies on these components. Continental and seabed surfaces are complex media where living organisms, air, soil, water, and rock interact. Resulting from physical transport and chemical transformation induced by fluxes of energy and matter, they play a major environmental role as a physical−biological−chemical reactor at the interface between the interior of the planet (lithosphere), the surface (hydrosphere, cryosphere, biosphere) and the outer envelope (atmosphere). These surfaces include the critical zone, the inhabited outermost layer of our planet, extending from the bottom of aquifers to the top of the atmospheric boundary layer. The critical zone supports almost all human activities and is currently subject to rapid and profound changes that impact living organisms and their environment.


In that respect, it is crucial to monitor, analyze and model the bio-geo-chemical cycles occurring at the Earth's surface including those associated with water, carbon, nutrients, organisms and/or rocks. The sensitivity of these cycles to climate change, how they interact, the changes they have undergone throughout geological time across the entire Phanerozoic, and how they may evolve in the future all continue to be open questions. Such studies extend to other planets and planetary bodies of the Solar System that have evolved in parallel to the Earth. Understanding the interactions between the many components of these surfaces across a range of timescales, from the early geological times to present time, and space scales ranging from the mineral interface and living cells to terrestrial planets, is an ambitious challenge that researchers at IPGP have undertaken. Indeed, over the years, our institute has pioneered a cross-disciplinary integrated scientific approach based on observations made at different scales by environmental networks and remote sensing sensors, analytical and experimental developments as well as coupled physical, chemical and biological models. In the next five years, IPGP will tackle innovative and groundbreaking projects aimed at furthering our understanding of the Earth and other planets as a whole system.


Five major challenges have been identified in the field of Earth surface processes:


• Biogeochemical processes in the critical zone: a fundamental understanding is needed to preserve our limited natural resources (matter, land and water) affected by a changing climate and anthropogenic activities.


• Landscape evolution: how and how fast are landscapes created by exogenic and endogenic processes acting at the interface between the lithosphere and the atmosphere and hydrosphere?


• Comparative planetary science: how analogous phenomena of various kinds (physical, chemical, morphological and so forth) manifest themselves in different planets?


• Paleoenvironments: what are the causes for the abrupt past changes in Earth surface dynamics recorded in sedimentary archives?


• The deep biosphere: how does it influence Earth's surface dynamics?