I believe it belongs upfront, because Kevin's comment did an excellent job of boiling it down to basics. If your struggling with figuring out the climate science contrarian mind-scape, here's a short but good read.
It's really pretty simple logic: By assembling a list that contains completely contradictory claims all PopTech is promoting is ignorance, uncertainty, and doubt. Color me surprised (/snark).
Knowledge is gained by comparing competing claims and discarding those that are not consistent with all the evidence.
As with most of the denialsphere, PopTech shies away from actual definitions.
The theory of AGW is pretty simple: Human activities have the net effect of making the planet we live on warmer. The theory is true. If not, there's a Nobel Prize awaiting the paper that shows our current understanding of radiative transfer is completely incorrect.
The only doubt then is magnitude and effect.