David Karoly is a Professor of Atmospheric Science in the School of Earth Sciences and the ARC Centre of Excellence for Climate System Science at the University of Melbourne. He is an internationally recognised expert in climate change and climate variability. He was heavily involved in preparation of the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) released in 2007, in several different roles. Professor Karoly provides advice to the Australian government on responding to climate change, including targets for reducing greenhouse gas emissions. He has held the Williams Chair in the School of Meteorology at the University of Oklahoma. During 2001-2002, he was Professor of Meteorology and Head of the School of Mathematical Sciences at Monash University.