It's amusing to see someone complain about the poor quality of education and then show himself to be poorly educated. Mr. Warren is so poorly informed that he thinks  "the evidence is slight" of man-made global warming, so I'm sort of at a loss to understand how he could evaluate much of anything. He doesn't even know that the Montreal Protocols (1987) resulted in a greatly reduced hole in the ozone layer.

There's no logical fallacy in concluding that human GHG emissions are warming the planet and disrupting a livable climate; science knows exactly what causes planetary warming and cooling, and there's no way to explain the current warming without factoring in anthropogenic GHG's. 

Finally, carbon dioxide is, in fact, toxic to humans at high enough concentrations, 10,000ppm, but atmospheric CO2 will be fatal to civilization at the current level of 405ppm . . . because it will warm the planet, acidify the oceans, raise sea levels and create an unlivable climate.