Carbon Dioxide (CO2) has cycled up and down with each ice age, ranging from approximately 180 to 280 ppm. It is now at 394 ppm and rising more than 2 ppm each year. The information is obtained from actual bubbles of gas trapped in the ice sheets of Greenland and the Antarctic, which can be deciphered similar to tree rings. The temperature record comes from the ratio of oxygen isotopes, both in the ice cores and in the layers of deep sea sediments. What cannot be discerned from this kind of analysis is any fine horizontal time scale. With 50,000 years being the unit of time on the horizontal scale, no conclusion can be inferred as to how quickly CO2 or temperature will tend to move in parallel with the other.