An article came to my attention showing that during a recent period (in geologic time), atmospheric CO2 fell over 1,000 ppm (its about 350 ppm now) while temperatures rose 7 degrees Centigrade (12.6 degrees Fahrneheit). Many questions came to mind. One, how much higher was global temperature then than now? Answer: about 12 degrees F. As the chart below shows, the Earth is usually warmer, and as expected, atmospheric CO2 was much higher because of the warmer seas and the higher rate of plant growth and subsequent decay. All natural, of course.
Now we are in a period of relatively low temperatures and atmospheric CO2. Atmospheric CO2 has increased about 80 ppm in the past 200 years, and warming increased a modest 0.6 degrees Centigrade (1 degree F) since the end of the Little Ice Age about 160 years ago.
Only Al Gore and his Acolytes would think that any of this is remarkable, or not natural. What is an icrease of 80 ppm for CO2 when previous fluctuations have been in thousands? What is an increase of 0.6 degrees C when geological records show rapid swings of 7 degrees C?
I have seen hundreds of peer-reviewed journal articles that establish such phenomena as a global Medieval Warm Period, a much warmer than present Holocene Optimum, and at least four other periods of equal or greater warming in the past 11,000 years. Arrayed against that is the discredited "hockey stick" of Mann et al, which among many shortcomings attempts to hide the divergence between what the trees are supposedly telling us compared to modern instument records. Can you have it both ways? Tree rings prove there was no Medieval Warm Period, but can't show current warming?
Concerning CO2 levels, 3% is produced by human activity, and 97% by the natural carbon cycle, which includes decaying plant material and the oceans. In terms of the nonexistent "greenhouse effect", water vapor contributes roughly 95% of atmospheric warming as the atmosphere acts as an air conditioner cooling and warming the Earth by a combination of thermodynamics and radiation.
CO2 is an insignificant trace gas, incapable of aborbing heat energy and reradiating it towards an area of greater energy concentration, the Earth. Simply, a cooler body cannot warm a warmer one.
All of the Warmist arguements are like speculating about the number of Angels who can dance on the head of a pin, without first proving the existence of Angels.