He studied Physics at Ecole Normale Supérieure, and specialized in the development of atmospheric or coupled ocean-atmosphere climate models.

He carried out simulations of the climate response to a CO2 increase since the mid-eighties, and analyzed the dependence of their response to a large range of feedback factors, including biogeochemical ones. Hervé Le Treut is the author or coauthor of more than 100 peer-reviewed papers. He is presently professor at University Pierre et Marie Curie (on leave from CNRS) and at Ecole Polytechnique. He is the director of Institut Pierre Simon Laplace, a federation of 9 laboratories of the Paris area. He has been a member of the Joint Scientific Committee of the World Climate Research Programme, and a regular participant in the IPCC Assessment Reports.

He is strongly involved in the studies at the interface between science and society, was a member of the pilot Committee of COP21, and coordinated a report on the adaptation to climate change in the South-West of France.