Dennys is an atmospheric chemist and has worked at the CSIRO as a Principal Research Scientist, as well as a lecturer at the University of Technology, Sydney (UTS). He was recently appointed by the University of New South Wales (UNSW) as a sessional convenor for the Postgraduate Program summer course, Managing Greenhouse Gas Emissions. Dennys has a Graduate Dip.Ed. and a PhD in physical chemistry from Macquarie University. He is a member of the Royal Australian Chemical Institute (RACI) and Clean Air Society of Australia and New Zealand (CASANZ) as well as a volunteer for the Citizen’s Climate Lobby, Australia.