The first line is about a model. The problems with the "simple" (their words) models they have constructed are legion. No computer they have ever created has been anything more than a joke. Any reference to a model in the Abstract thus renders the entire study worthless. That's the whole point. AGW theory is based almost entirely on failed computer models.
Well, now, there's a scientific and objective way to clearly identify the nature and extent of the flaws you've identified with the research papers you seemingly haven't even bothered to read.
From what I can see there is no scientific discussion to be had with the majority of people who reject climate science. Since they are rejecting science as a whole.
This article contains the most basic science that clearly establishes just how we can be sure that virtually all the excess carbon in the atmosphere since the early 1800s comes from fossil fuel sources.
See
How do we know that recent CO2 increases are due to ...
It is extremely well researched, provided multiple citations and innumerable references to very well established science as well as depending on multiple published works.
But its cast aside as a "lie"
I don't think its really possible to discuss science with people who insist science is a "lie"
What you don't see, because you don't understand even the basics is there is precious little real science on your side. I am curious. What scientific classes have you attended? Do you know what the scientific method is, and can you describe it in your own words?