Philippe Ciais is director of research at the CEA, Laboratory of Climate and Environmental Sciences LSCE(CNRS/CEA/CEA, UVSQ - Paris-Saclay University), Pierre Simon Laplace Institute. A researcher at the Laboratoire des Sciences du Climat et de l'Environnement, he studied how the planetary carbon cycle is influenced by human activities and its feedback on the climate. His work has led to a better understanding of the distribution of natural carbon sinks in vegetation and soils. Philippe Ciais notably coordinated the implementation of the European measurement and observation network ICOS, aimed at quantifying greenhouse gas emissions and carbon sinks across the European continent. He has also developed compact or complex models of terrestrial ecosystems to identify the factors that determine carbon exchanges between vegetation and the atmosphere.