The Manhattan Declaration, issued by scientists sceptical about manmade global warming, warns that:
"attempts by governments to legislate costly regulations on industry and individual citizens to encourage CO2 emission reduction will slow development while having no appreciable impact on the future trajectory of global climate change. Such policies will markedly diminish future prosperity and so reduce the ability of societies to adapt to inevitable climate change, thereby increasing, not decreasing, human suffering."
Link to Manhattan Declaration.
Update (14 May 2008): Excellent summary of the current state of play by Mike McNally.