I think I'd prefer to let this discussion rest, but here's at least a partial answer to your questions:
How would you know that to be true?
Because the atmospheric physical chemistry involved has been studied for over 50 years? Exxon has known about it that long, for example.
en.wikipedia.org
When you say "perhaps a few percent" you reveal the fact that you have no way of knowing. If in fact "thousands of people" have analyzed the data, what percentage understood the data?
The scientific consensus on climate change is discussed here (may be somewhat dated):
en.wikipedia.org
To quote in part "Dennis Bray and Hans von Storch conducted a survey in August 2008 of 2058 climate scientists from 34 countries . . . To the question "How convinced are you that climate change, whether natural or anthropogenic, is occurring now?", 67.1% said they very much agreed, 26.7% agreed to some large extent, 6.2% said to they agreed to some small extent (2–4), none said they did not agree at all."
That was 15 years ago, the evidence now is even stronger.
Scientific credentials about a subject as foreign as global warming are what exactly?
Ideally someone who's professional career involves research on some aspect of the subject, but certainly at least a master's degree in the field or an allied field like chemistry or physics. You know, just like you need a degree and accreditation to be a practicing engineer or a practicing architect.
An honest assessment of the issue would include an admission that there is no perfect knowledge or answer. The pronouncements from on high would include "we think" at every turn. Why is that so hard to admit? Do you have the temerity to scoff at naysayers? Such an attitude grates on so many.
In this discussion, I regret if I have presented my statements about climate science as 100% certainty versus, say, 90% - 99% certainty. [On the math comments, I am 100% certain.] 90% certainty is certainly enough for planning.
In fact, the IPCC (International Panel on Climate Change) has explicit guidance on this for the reports they publish. They suggest terms like "virtually certain" for 99%-100% likelihood, and "very likely" for 90%-100% likelihood, etc.
Popular discussion is obviously rarely so nuanced, and I agree I didn't pay attention to what confidence level to ascribe to each of my statements.
What I do know is that the supposed cure will kill the patient. If you want to save the future for our children....find a smart answer.
You are focusing on an extreme intervention, effectively banning oil and gas extraction in the US this year. I agree that 20 years from now, we'd probably be worse off if we did that than if we did nothing and let the status quo continue and global warming worsen.
But nobody is proposing to go cold turkey this year. There is an obvious middle ground, which is to taper to zero over 20 to 30 years.
Cheers, Wayne