Your last big paragraph is filled with illogic. Has there ever been great climate change during a time in the historical record to compare with? (You even mention economic decisions, suggesting this "never seen long term famine" observation is exceedingly modern.) The fact that LA was once under sea water naturally doesn't mean that human action can't put it back under. (And by extension, act otherwise to prevent it from happening.) Ancient CO2 levels are also not particularly relevant considering how drastically different our climate is from then. The threat of global warming is not that the globe will become uninhabitable (unlike global thermonuclear war, that is not a claim made) but rather that the changes in the climate will create havoc: extreme and damaging weather, species may die out, areas which once grew one thing may no longer be suitable or ideal for that growth, desertification may occur in some areas, etc. Sure, perhaps some areas that were non-ideal (for habitation, agriculture, etc.) will become ideal, but we are not poised to take advantage of that... it will be a slow learning process.
The projected impact is very much economic, which is funny because you suggest the power of economics and then disregard it. Do you think that with the interconnectedness of our economies we would really weather such chaos well?