We will likely act too slowly on this and have to turn to CO2 scrubber technology. Unproven and likely many unintended consequences. I hate to assume technology will 'save' us on this but we're going to have to hope so. What countries did when addressing the ozone challenge was and is encouraging. A lot of smart people understand and want to do something about the climate change challenge so I'm optimistic that although we'll be late to the party we'll still get it done. The consequences if we don't... Let's just hope we do. I'm in the middle of reading a Climate Change in Prehistory: The End of the Reign of Chaos and if we go back to those crazy unstable climates we are going to be in serious trouble. Humans will survive it but it won't be pretty.