He is Professor of Economics at Stockholm University and holds a part-time position as Centennial Professor at London School of Economics. He held assistant-professor positions at Northwestern University and the University of Pennsylvania, as well as full-professor positions at the University of Rochester and Princeton University. He is the elected President of the European Economic Association. His research has focused on macroeconomics, broadly defined, with particular contributions in the areas of technological change, inequality, political economy, macroeconomic policy, and labor economics. He is currently pursuing a long-term project on the interactions between global sustainability, in particular climate change, and the economy. For his work he has received numerous awards and grants.