A Cornwall Alliance follower on Facebook wrote,

I remember hearing someone reputable say once that the known historical record actually shows increases in CO2 after periods of warming, rather than before them. I believe might have been referencing ice core records among others. I found him persuasive, and if this is true, it seems it would be an important hurdle for climate change alarmists to get over. Agree/disagree, insight?

Climatologist Dr. David Legates, a Cornwall Alliance Senior Fellow, addressed the question of whether CO2 leads temperature or vice versa in an article several years ago.

The causal relationship is actually both ways, but it appears that temperature-leads-CO2 outweighs CO2-leads-temperature.

Over long periods, CO2 follows temperature by about 400 to 1,000 years, according to the ice core records. Over shorter periods, CO2 can follow temperature by periods on the order of 12 to 40 or so years. (And there are more wrinkles.)

Because CO2 is an infrared- (heat-) absorbing gas, pretty basic physics does tell us that as its concentration increases in the atmosphere, the result (other things being equal—and many aren’t) will be an atmosphere somewhat warmer than it otherwise would be, so CO2 can indeed cause some warming.

But because seawater absorbs more CO2 when it’s cooler and less when it’s warmer (just as a can of carbonated beverage fizzes more intensely when warm than when cold), a warming ocean puts more CO2 into the atmosphere, and a cooling ocean takes more CO2 out of the atmosphere.

Because the ice cores indicate what I stated above, it appears that the “inhaling/exhaling” (sequestering/emitting) action of the ocean more strongly controls atmospheric CO2 concentration than atmospheric CO2 concentration controls ocean (or air) temperature.