Msurkan on the openDemocracy "Politics of Climate change" page asks whether it is possible to make a difference to climate change by CO2 reductions.
The Global Commons Institute http://www.gci.org.uk/ is well worth study; there are dynamic graphs there which show the effects of various CO2 reduction scenarios. CO2 reductions can make a difference, so long as they are radical.
Happily, emission reduction is only part of the solution. CO2 sinks, primarily reafforestation, can also play a part, if done properly, with diverse plantations of the right species, carried out with the cooperation of local communities. Ocean fertilisation also carries promise. In the past, these approaches have been controversial, but as the seriousness of the situation becomes apparent to everyone (with the exception of a very few individuals), they will be re-evaluated and carefully implemented.
The change from the present economics based on immediate gratification, to a rational economics based on workng with planetary systems to the good of all is not difficult. We know exactly what to do from the standpoint of economics ( http://www.greenhealth.org.uk/GreenEconLonger.htm ). It is the politics - persuading leaders to make choices that benefit the peoples of the world, rather than choices that benefit their paymasters such as Exxon-Mobil - that is the stumbling block.
One of the most extraordinary things in the current situation is the ease with which commentators who last year were denying the reality of climate change have made an effortless transition to saying that it is too late to do anything about it.