Climate change is a global problem. Worldwide emissions cannot be curbed to the extent required without meaningful contributions from all major economies. The international community's response to climate change has therefore, quite rationally, focused on globally coordinated collective action. Yet national legislation is as critical to combating climate change as a successful international agreement. International commitments have little meaning unless they are underpinned by legislative action at the national level. More subtly, national legislation can alter the dynamics at the international level. Domestic debate can help to advance national positions and give leaders the confidence to go further in the formal UN negotiations. These dynamics are particularly important at a time when international progress is slow.