So let's start with some FACTS. The Atmosphere is Composed of Currently ~400 Parts per million of CO2, IOW .004 of the atmosphere is CO2.
Of that CO2 Human activity is responsible for about 3% of Global CO2 levels IOW, .004x.03. 0.00012 of the atmosphere is CO2 generated by humans.
IF humans were to reduce their CO2 foot prints to zero they would remove 0.00012 of the CO2 from the atmosphere.
So speaking of Risk what would happen to humans if we did away with all CO2 emissions, mass poverty, starvation and death.
Try to live without electricity, transportation, and food grown without multicultural machinery or fertilizers for a month and get back top us.
The Global Greenhouse effect is caused primarily by water vapor ~95%. Now selling H2O as a pollutant is a rather tough sell. So the theory was ( not sure if the goalpost have been moved on the basic premise), that CO2 led to a positive feedback loop with water vapor to induce accelerated warming.
See CO2 by itself is logarithmic in effect, past a certain point it takes a doubling to produce a small change. The next doubling produces a much smaller change and so on. Well that doesn't help with crisis mongering so a positive feedback was proposed. It was said that the warming in the lower troposphere caused by this feedback effect would be 3x the effects with ground temperatures. The problem is that this 'fingerprint' has never been observed in the real world.
Those of you familiar with cricuit design realize what happens when a circuit has a positive feed back rather than negative feedback.
Would you be surprised to know that for much of the earth history that CO2 levels were almost a order of magnitude greater than current levels?
so if there is a positive feedback that would lead to a runaway greenhouse effect, why didn't it happen when CO2 levels were 2000-4000 ppm over hundreds of millions of years? Did the laws of physics change?