From the article:
Working Group III of the IPCC, which reported at the beginning of May, said at great length that in fact it was technically feasible to reduce emissions to the point where temperature rise could be held below 3.6 degrees Fahrenheit, or 2 degrees Celsius—the point where many climate scientists now believe global warming may turn from a miserable problem into a catastrophe.Do they? I think 2 C is not a tipping point, it's the best we can conceivably manage. Which side of 2 C the problem gets severe enough to push us over the edge and into decline is something I believe is completely unknown. I will point out that a 100 C warming actually would be catastrophic. I am not suggesting that this will happen. I am saying that there is some amount of warming that would be catastrophic, and it's surely less than 100 C.
It may be prudent to act as if the number were less than 2 C. I don't see where 2 C is some magic number as far as climate science is concerned, though.
Thanks to 3 Quarks Daily for the link.