I agree steelish... the Vikings (with inifinite humor?) named a northern island Greenland, settled there, and also settled in the then balmy climes of Newfoundland.
It's been warmer, it's been colder. We've been keeping close track all of what, 200 years?
The Sahara was lusher when it was warmer and less water trapped in the icecaps. Even some 2300 years ago. Remember Carthage? (Well probably not, thanks to the Romans.Who says violence doesn't solve anything?...) Well, they were every bit as powerful and prosperous, in the Sahara. It was a different climate.
Remember that neolithic "Iceman" recently uncovered by a retreating glacier, who fell and died in the Alps... wearing relatively mild weather garb? He was far far higher than need be unless the climate offered opportunity based resources.
And the dinosaurs must have been farting a lot of greenhouse gases back in their time.
Remember Krakatoa? Vesuvius? Mt. St. Helens? A volcano can pour far more tonnage into the air in mere moments than can humanity despite all our efforts. Remember the Dark Ages? Many historians now believe it really meant dark ages. When the amount of light getting through the volcanic dust clouds sent into the air was reduced in the northern hemisphere. I can see it now, a really big volcano goes off, reducing captured heat, and we have to shut off all the CO2 scrubbers to help keep greenhouse gases high to retain more heat.
All that said, do we have an impact? Of course we do, but we are neither the cause nor the solution. Can we do some things to mitigate the impact? Of course we can and should. Are there things we should be doing for other reasons, (like getting off of foreign oil,) that we are promoting as a cure for global warming? Yes, we should, so I don't have an issue with many of the conference's goals...
But mostly I think it is our very hubris that somehow we are to blame that will get us in trouble again later, when the sun cools again, or we miss an opportunity because we're blinded by our own conceit.