Carbon Dioxide Has Not Controlled Earth's Past Temperatures; Carbon Dioxide Has Been a Lagging Indicator; Its Concentrations Rising about 600-800 Years AFTER the Temperatures Warm

Recently the CO₂ levels in the Earth's atmosphere and temperatures on the Earth's surface have both been rising. Does that mean that high CO₂ levels have been causing the Earth's warming? Or is it just coincidence?

According to the greenhouse theory, more CO₂ in the Earth's atmosphere will trap more of the Earth's own radiated heat, warming the lower atmosphere and ultimately the surface of the planet--all other things being equal. But the fact that the Earth's temperature has warmed only slightly since 1940, despite the huge clouds of greenhouse gases emitted from human activities, provides evidence that the human greenhouse effect must be so small that it presents little threat to the planet or its people. This is especially true since each additional unit of CO₂ causes less warming than the previous unit. . . .

The Antarctic ice cores tell us that the Earth's temperatures and CO₂ levels have tracked closely together through the last three ice ages and global warmings. However, CO₂ has been a lagging indicator, its concentrations rising about 600 to 800 years after the temperatures warm.

--S. Fred Singer and Dennis T. Avery, Unstoppable Global Warming: Every 1,500 Years, updated and expanded ed. (Lanham, MD: Rowman  and Littlefield Publishers, 2008), 107-108.