The offered set point for when anthropogenic global warming (AGW) kicked in is when the climate started to warm. The actual data from the seabeds is that the CO2 emissions from human fossil fuel use started to be measurable in the 1830’s.
Why didn’t AGW start in the 1830’s? Because there wasn’t enough CO2 to cause warming until later, when the temperature records started to increase significantly.
How much CO2 emission is required to start the climate warming? “I dunno, let’s look at the charts.”
What do the models tell us? “That this much CO2 will cause AGW.” How were those models developed? “Based on the charts.”
See? It’s honest-to-goodness begging the question. Maybe AGW happens to be correct despite the sloppy method. One side says, “we’re all gonna burn in ‘Hell on Earth’ if we’re right.” The other side says, “I’m not spending $300T on that bet.”
As an attempt to isolate the variables people look to other planets. They see warming there. That’s a reasonable indication that there’s a common cause, though no proof that AGW isn’t happening too.
In the end it’s a business decision, but one that affects everybody, one way or the other. We can’t predict the future with confidence, but we can control our behavior in the present. Making moral decisions now is the best we can do.