Just days before the United Nation’s historic Copenhagen summit the Munk Debates tackled one of the great public policy questions of our time: how should the world respond to climate change? CO2 levels in the atmosphere are climbing steadily higher. Some believe this is having a devastating effect on humans and nature, while others argue that the threat has been overstated. Is this the moment for a bold international treaty to curb carbon emissions? Or, are the social and economic costs of reducing CO2 emissions too high in a world where a billion people live on a dollar or less a day?