The infamous Gore-Mann-Jones Hockey Stick Graph has a time axis is of the order of a thousand years. It must be pointed out that this representation is largely NOT based on direct temperature measurement, but rather proxy data. Chief amongst these is that of the tree-ring record. There are many problems with these data; e.g., sample selection - over how much of the Earth do trees actually grow? Although for now it is salient to point out recent (decadal) tree-ring evidence directly contradicts the physically measured temperature record. Climate scientists themselves have a name for this; they call it - "the divergence". The question that likely springs to mind to any reasonable scientist or layman is if we currently have a divergence between the tree-ring and temperature record then how reliable is the tree ring data as a proxy for past temperatures? Why, for example, does the historically well documented Medieval Warm Period or subsequent Little Ice Age not feature in the largely horizontal Hockey Stick Graph's base-line? If current temperatures are not unprecedented then how can we be sure what the principal driver(s) is? Indeed, in the geological record (even on a very short millennial scale), the ice core data, for example, would suggest that there is nothing exceptional about current temperatures.
I also have concerns about unalloyed computational modelling which has been used as a predictive tool. Most of these models actually ignore, for example, the clouds as an input – maybe this should tell us all we need to know on that front. I have rattled on about this here in the past so maybe I shouldn't repeat myself excessively now.
My view in summary is then yes CO2 is indeed a greenhouse gas. However, given the complexity of the as yet poorly understood climatic/weather system, to say its heightened anthropocentrically derived input to the atmosphere will necessarily raise GMST (global mean surface temperature) is undeniably simplistic, perhaps to the point of being wrong. Finally there is nothing wrong with scepticism that is how knowledge, particularly in the sciences, advances. The record shows that every certainty is eventually overturned and that critical thinking, observation and experimentation are all that ultimately counts. As for consensus - that is for politicians, not scientists.