William M. Last is a professor in the Department of Geological Sciences at University of Manitoba (Canada) and is co-editor of the Journal of Paleolimnology. John P. Smol is a professor in the Biology Department at Queen's University (Canada), with a cross-appointment at the School of Environmental Studies. He co-directs the Paleoecological Environmental Assessment and Research Lab (PEARL). Professor Smol is co-editor of the Journal of Paleolimnology and holds the Canada Research Chair in Environmental Change.