Stephen Hesselbo is Professor of Geology and Deputy Head of the Department of Earth and Environmental Sciences. His research interests are broadly in the area of Earth history and timescale, and particularly the interplay of long-term environmental changes and short-term shocks to the system.

Service to the international community includes acting as Chair (from January 2025) for the Science Advisory Group of the international Continental Scientific Drilling Program (ICDP). He has previously been co-leader of an International Geoscience Project (IGCP 458) on Triassic/Jurassic Boundary Events, an interdisciplinary study of the Triassic–Jurassic boundary mass extinction. He has experience of the international scientific ocean drilling, having been a shipboard scientist on the (International Ocean Drilling Program) IODP Legs 150 (1993) and 174a (1997), and a member of the Science Party on Expedition 313 (2009) aimed at understanding global sea-level change from 30 to 14 million years ago. He is past chair of the International Subcommission on Jurassic Stratigraphy, and Emeritus Fellow at St Peter's College, Oxford.