When should the United States take action to address climate change?
• In October 2001, the Pew Center on Global Climate Change held a workshop inviting leading scientists, economists, and other analysts to address this question. The workshop revealed a consensus that action to address global climate change must begin now if it is to be effective. An immediate signal that initiates action is required in order to provide a smooth and cost-effective transition to a stable concentration of GHGs in the atmosphere-a challenge that will take decades, if not generations, to meet. As the scientific literature makes clear, we do not need to know more in order to conclude with confidence that the trend towards a warmer global climate is real, and that action should begin now. Waiting to take action ignores the strong evidence that GHG concentrations in the atmosphere are building and if left unchecked will exceed a doubling of their pre-industrial levels. Other compelling reasons to begin taking action include the potential for catastrophes that defy the assumpti
