The United States and the world face a climate crisis and a narrowing window of action to avoid the worst impacts of climate change. At the same time, the transition to a low carbon economy represents a historic economic opportunity for the U.S. and global economy. The U.S. federal government must work alongside our domestic and international partners to respond ambitiously to tackle the challenges of climate change, adapt to an already changing climate, mitigate the risks, and position the global economy for clean and sustainable growth.