Prof Rayner’s main research activities focus on the estimation of surface sources and sinks of CO2. He uses satellite and in-situ measurements with models to quantify and understand the patterns and mechanisms of CO2 release and uptake with a focus on the tropics and Southern Hemisphere. In 2002, Prof Rayner was awarded the Priestley Medal of the Australian Meteorological and Oceanographic Society, the major research award in this field within Australia. Prof Rayner originally studied theoretical physics and mathematics at the University of Melbourne, Australia, where he completed a PhD in paleoclimate in1991. After a brief foray into atmospheric dynamics he has spent the past two decades studying the carbon cycle at various scales and its interaction with the climate. He has concentrated on the application of statistical inference (going under various names such as inverse modeling or data assimilation) to problems in biogeochemistry. ​ Prof Rayner has also worked at the National Center for Atmospheric Research and Princeton University in the US, the Commonwealth Scientific and Industrial Organisation. Monash University in Australia and the Laboratory for the Science of Climate and the Environment in France. He currently holds an Australian Professorial Fellowship at the University of Melbourne.