Professor Andrew Roberts has made fundamentally important contributions to understanding the magnetisation of sediments, which provides the basis for use of paleomagnetism to reconstruct global plate tectonic movements and to understand variations in Earth’s magnetic field through its history. His work influences all aspects of understanding sedimentary magnetisation acquisition, and has particularly contributed to recognising that the previously poorly-known magnetic mineral greigite, and magnetic minerals produced by magnetotactic bacteria, make important contributions to the magnetisation of globally distributed sedimentary rocks. He is an international leader in the field of environmental magnetic analyses of climate change, and has developed new methods in rock magnetism that are used widely in solid state physics, materials science, the magnetic recording industry, and Earth science. His work in environmental magnetism has made significant contributions to understanding African monsoon dynamics, sea level variations, and Arctic and Antarctic glacial history.