A. What are the Historical and Typical CO2 Fluctuations?

Background.  The IPCC 1990 at page xiv states its basic assumptions and three reasons why the Greenhouse Effect is true.   The first two reasons were discussed in Question 7 (Venus & Mars) and Question 8 (Black Body analysis).  This sections deals with the third and final reason.

“We know that the greenhouse effect works in practice, for several reasons.”

….

“Thirdly, measurements from ice cores going back 160,000 years show that the Earth’s temperature closely paralleled the amount of carbon dioxide and methane in the atmosphere (see Figure 2). Although we do not know the details of cause and effect, calculations indicate that changes in these greenhouse gases were part, but not all, of the reason for the large (5-7″C) global temperature swings between ice ages and interglacial periods.”

 The IPCC limited its geological history to ice cores going back 160,000 years even though ice cores provided evidence going back millions of years.  Quorvita could not locate where the IPCC backed up any of the three grounds with calculations, analysis, or citation of specific scientific laws and principles.

Data.  The Historical CO2 fluctuations over the last 570 million years [World Data Center for Paleoclimatology and NOOA Paleoclimatology Program; R.A. and Z. Kothavala, 2001, GEOCARB III: A Revised Model of Atmospheric CO2 over Phanerozoic Time, IGBP PAGES/World Data Center for Paleoclimatology  Data Contribution Series # 2002-051, NOAA/NGDC Paleoclimatology Program, Boulder CO, USA ] is shown in the figure below.

This information is consistent with other reported historical CO2 concentrations. [Ekart, D D et al (1999) A 400 Million Year Carbon Isotope Record of Pedogenic Carbonate; Implications for Paleoatmospheric Carbon Dioxide, American Journal of Science, Vol 299, pg 805-827.] 

As shown above, the average CO2 concentration for the entire 570 million years was 2560 ppmv with a standard deviation (normal fluctuation) of 2057 ppmv.  The earth is currently at 407 ppmv which is 6 times lower than the average and 5 times lower than the normal fluctuation.  The red line indicates that Earth is at a dangerously low level for potential plant extinction.  Laboratory studies have shown that a CO2 concentration between 180-220 ppmv results in C3 plant growth dropping by 50%.  Almost all plants are C3.  Extrapolation studies point to 150 ppmv CO2 as a potential plant extinction event.  If plants die then animals die.  Care must be taken in using technology to reduce CO2 on a wide-spread industrial scale.