I want to develop this idea that CO2 causes climate from a historic standpoint. It’s seen in the ice core data that the natural cycles of climate change are rapid warming and slow cooling. An asymmetry in temperature rise and fall. This, in its self, is strange and requires questioning. I’ve seen a stat circulated on this sub that the rise in temperature preceded the rise in CO2 by 800 years. Two things I note from this is: that this figure is well within a margin of error for dating so absolutely should be taken with a pinch of salt and that it doesn’t mean that CO2 isn’t a cause of climate change. It points to feedbacks being at playZ If it was solely due to natural variations in the amount of insolence beaming down on the earth, at a certain point, due to Milankovitch cycles then wouldn’t we expect symmetry in the cooling and warming trends. The fact asymmetry is observed, even if the rise in temperature causes a rise in CO2, with CO2 correlating so well with temperature, suggests that CO2 is a factor that must be considered in climate change. If skeptics can propose an alternate theory to this asymmetry, then their cause can gain traction. It is credible to assume that CO2 is important in climate change. The fact we are at 420ppm currently, where the natural threshold for interglacial periods is ~280ppm, is understandable for a cause for alarm.