The existence and urgency of global climate change is a matter of scientific consensus. Yet the global politics of climate change have been anything but consensual. In this context, a wave of global climate activism has emerged in the last decade in response to the perceived failure of the political negotiations. This book provides a unique comparative study of environmental movements in USA, Japan, Denmark and Sweden, analyzing their interaction with the international climate institutions of the United Nations, with national governments, and with currents in the global climate movement. It documents how and why the movement evolved between the Copenhagen Summit of 2009 and the Paris Summit of 2015, altering its strategies and tactics while attracting new actors to the issue area. Further, it demonstrates how the development of global environmental networks has increased contact between environmental movements in the Global North and those from the Global South, resulting in the establishment of 'climate justice' as a political cause and unifying frame for global climate activism.