Participants from academia and various levels of government gathered in Ottawa to discuss the often underappreciated interplay between the international climate agenda and the global trade system. The trade system has traditionally supported open flows of goods and services by disciplining tariffs, as well as trade-distorting subsidies and regulations. But there is an emerging tension between this approach and the desire of governments to address climate change through potentially trade-distorting domestic regulations and green subsidies. The challenge for policy makers is how to maintain relatively free, undistorted trade, while still giving countries sufficient policy space to implement effective measures to combat climate change.