the dramatic increase (implying a dramatic cooling) over the most recent two million years, when the air’s CO2 concentration has risen slightly. In another detailed review of Earth’s thermal and CO2 history, Pagani et al. (2005) examined these parameters over the most recent 50 million years. Their examination revealed essentially the same findings as the study of Pearson and Palmer (2000). As demonstrated in Figure 22.214.171.124.3, about 43 million years ago the atmosphere’s CO2 concentration was approximately 1,400 ppm and the oxygen isotope ratio (a proxy for temperature) was about 1.0 per mil. Then, over the next ten million years, the air’s CO2 concentration underwent three huge oscillationson the order of 1,000 ppm from peak to valley (Figure 126.96.36.199.3, red). In the first two oscillations, temperature appeared not to respond at all, exhibiting an uninterrupted slow declinerepresented by the steady upward trend in δ18O. Following the third rise in CO2, however,temperatures seemed to respond, but in the opposite direction to what is expected according to the CO2-induced global warming hypothesis—the rise in CO2 was followed by the sharpest drop in temperature(rise in δ18O) of the entire record. Following this large drop in temperature between 34 and 33 million years before present (Ma BP), the oxygen isotope ratio hovered around a value of 2.7 per mil from about 33 to 26 Ma BP, indicating little change in temperature over that period. The corresponding CO2 concentration (Figure 188.8.131.52.3, green) was anything but constant, experiencing about a 500 ppm increase around 32 Ma BP, after which it dropped a full 1,000 ppm over the next two million years, only to rise again by a few hundred ppm, repeatedly defying the common causal assumption of the CO2-induced global warming hypothesis. Around 26 Ma BP, the oxygen isotope ratio dropped to about 1.4 per mil (implying a significant rise in temperature), during which time the air’s CO2 content (Figure 184.108.40.206.3, yellow) declined, once again the opposite of what one would expect were CO2 driving climate change. Then, from 24 Ma BP to the end of the record at 5 Ma BP, there were relatively tiny variations in the atmosphere’s CO2 content (Figure 220.127.116.11.3, blue) but large variations in oxygen isotope values, both up and down. These observations, according to Pagani et al. (2005), “argue for a decoupling between global climate and CO2” and stand in clear contradiction of the CO2-induced global warming hypothesis. Pagani et al. (1999), working with sediment cores from three deep-sea drilling sites, also found the air’s CO2 concentrationto be uniformly low(180 to 290 ppm) throughout the early to late Miocene(25 to 9 million years ago), at a time when deep-water and high-latitude surface water temperatures were as much as 6°C warmer than today. They stated their finding “appears in conflict with greenhouse theories of climate change.” In addition, they noted the air’s CO2 concentration seemed to rise after the expansion of the East Antarctic Ice Sheet, also in conflict with greenhouse theories of climate change.