His main research interest is the understanding of how and why the climate, in particular its extreme weather and climate events, has changed over the past century and how it is likely to change in the future. He works closely with the users of climate information. He is a Fellow of the Royal Society of Canada. He serves as Editor-in-Chief for journal Weather and Climate Extremes. He served as a coordinating lead author for the chapter on Weather and Climate Extreme Events in a Changing Climate of the IPCC 6th Assessment WGI Report, and he was also a lead author for the IPCC Special Report on managing the risks of extreme events and the 5th Assessment Working Group I Report. He led the assessment on changes in temperature and precipitation for Canada’s Changing Climate Report.