It sounds authentic to me, though I don't know who he is.
I thoroughly read the most recent IPCC report, and I conclude that it is total garbage. I'm a chemist and a pathologist, not a climatologist, but I certainly know how to read scientific reports. I have taught statistics, and I also understand mathematical models and their limitations. The IPCC report contained poor science, terrible models, and completely unsupported conclusions.
The CO2 issue is more complex than what Adiran and Pieter noted. Even if we assume that CO2 is a 'warming' gas in the atmosphere, its impact is small compared to water vapor (which, based on greenhouse studies, has 20 times the warming effect because of better solar heat absorption and higher concentration). Methane is also a 'warming' gas, but its concentration is too low to have any significant impact on global temperatures.
The positive feedback discussion by the IPCC and by Warren Meyer irks me. First, positive feedback is a psychology term about how an organism responds to good (positive) stimuli. The term the IPCC really wants is something like multiplicative effects or potentiation (when two or more things combined give an effect that is multiplicative rather than additive, such as ethanol and barbiturates). But, in chemistry and physics, examples of multiplicative effects are rare. The IPCC models are so bad that they can essentially apply their forcing factors to anything (too many people hopping on one foot) and claim it relates to global warming. I trust nothing from the IPCC, because the group is about keeping itself funded and influential with governments. The IPCC is not about climatology.
"the group [IPCC] is about keeping itself funded and influential with governments" - true, but I would add to it: it's also about spewing their (vile) ideological viewpoint.
The confidence I have in the UN's IPCC report is about the same I have in the UN's human rights comission, headed by Ghaddafi's (Lybia) representative.