B. Do Temperatures Control CO2 levels?
Which came first, the chicken or the egg is the proverbial question. In this context, did an increase in CO2 cause the temperature to rise or did temperature cause the CO2 to increase. That question has been answered.
Veizer et al were involved in logging the temperature trends during the Phanerozoic era using changes in the Oxygen 18 isotope ratio. This data went back 550 million years. This study found that several periods the temperature predictions based on carbon dioxide concentrations were not supported, indicating a decoupling (non-relationship) between Carbon Dioxide and Temperature. [Veizer, J, Godderis, Y, & Francois, L (Dec 7, 2000) Evidence for decoupling of atmospheric CO2 and global climate during the Phanerozoic eon, Nature, Vol 407.] This went to the heart of the the Greenhouse Effect theory and was immediately challenged by Dana Royer Royer, D. et al, (2004) CO2 as a Primary Driver of Phanerozoic Climate, GSA Today, Vo 14, No 3, 4-10 for using records that were not corrected by pH effects. Dana Royer was quoted multiple times in numerous assessment reports by the IPCC while Veizer J was not cited once.
In Robinson A.B, Robinson N.E., & Soon W (2007) Environmental Effects of Increased Atmospheric Carbon Dioxide, Journal of American Physicians and Surgeons, Vol 12, No. 3, pgs. 79-90 the authors studied the timing of temperature increases and carbon dioxide rising using the last 500,000 years and found that:
“Figure 16.Temperature rise versus CO2 rise from seven ice-core measured interglacial periods; from calculations and measurements of sea water out-gassing; and as measured during the 20th and 21st centuries. The interglacial temperature increases caused the CO2 rises through release of ocean CO2. The CO2 rises did not cause the temperature rises.” Emphasis Pg. 84.
If the CO2 rises AFTER the temperature increases, then such observation is directly contrary to the argument that CO2 causes the temperature to rise. Robinson et al stated:
“Hydrocarbon use is uncorrelated with temperature. Temperature rose a century before significant hydrocarbon use. The temperature rose between 1910 and 1940 while hydrocarbon use was almost unchanged. Temperature then fell between 1940 and 1972 while hydrocarbon use rose by 330%. Pg. 82.
The publication also plotted the number of Atlantic hurricanes making landfall, the number of maximum hurricane wind speeds, and the number of violent Atlantic hurricanes (pg. 81). It showed NO INCREASE in any of them over the average for the last 60+ years. It also found that the amount of rainfall increased slightly by about 6 percent per 100 years. The number of F3 to F5 tornadoes between 1950 and 2006 dramatically went down in the United States by 43% (pg. 80). On the other hand, the amount of agricultural growth in plants had increased 30%. Cutting CO2 emissions will decrease food production significantly while adding CO2 will increase food production. The Robinson publication was not cited or referenced in any of the IPCC’s many Assessment Reports.
A study by Fischer, H, et al (1999) Ice Core Records of Atmospheric CO2Around the Last Three Glacial Terminations, Science, Vol 283, pgs. 1712-1714 reported that the rise in CO2 concentration lagged temperature increases by 400 to 1000 years. The records also showed that the CO2 concentrations remained constant although there was a significant drop in temperature. There were many historical situations where there were CO2 concentrations over 1000 ppmv during ice or cold periods. Ekart, D., Cerling, T., Montanez, I. and Tabor, N. (1999) A 400 Million Year Carbon Isotope Record of Pedogenic Carbonate: Implications for Paleoatmospheric Carbon Dioxide. American Journal of Science, 299, 805-827; Retallack, G. (2001) A 300-Million-Year Record of Atmospheric Carbon Dioxide from Fossil Plant Cuticles. Nature, 411, 287-290; Sigman, D. and Boyle, E. (2000) Glacial/Interglacial Variations in Atmospheric Carbon Dioxide. Nature, 407, 859-869; Rothman, D. (2002) Atmospheric Carbon Dioxide Levels for the Last 500 Million Years. Proceedings of the National Academy of Sciences of the United States of America, 99, 4167-4171.
The wording used by the IPCC that states a “closely parallel” connection does not say which came first, i.e. “show that the Earth’s temperature closely paralleled the amount of carbon dioxide.” Technically this may be true, but it was the temperature that made the CO2 to increase not the other way around.
IPCC Admits CO2 Rise lags Temperature Change. In 2007 IPCC report at page 105, the IPCC admitted this lag relationship and changed its position to an enhancement theory.
“However, it now appears that the initial climatic change preceded the change in CO2 but was enhanced by it (Section 6.4)”
This is a 100 percent change from the IPCC position in 1990. In 1990, the IPCC stated at page 47 that water vapour is the most important greenhouse gas but it is considered a natural consequence of the warming and is thus a feedback from CO2 and other man-made Greenhouse Gases. The IPCC also classified “clouds” as a feedback because clouds are a consequence of water vapour. If the temperature increase/decrease occurs before CO2 rise/fall then it is the cause and not the result.
In 2007 the IPCC’s position changed from one where CO2 caused a temperature increase to one where CO2 enhanced the amount of Temperature increase and referenced Section 6.4. However, IPCC Section 6.4 did not provide any proof of this enhancement. It stated:
“it may be the result of increased ocean heat transports due to either an enhanced thermohaline circulation (citations) or increased flow of surface ocean currents.” (pg. 442);
“enhanced biological production and increased dustiness (iron supply) are coincident with CO2 concentration changes of 20 to 50 ppm” (pg 446); or
“precipitation-sensitive records and models indicate that summer monsoons in Africa, India and Southeast Asia were enhanced in the early to mid-Holocene due to orbital forcing,” pg. 464.
None of these quoted statements support the position that the temperature increase was enhanced by the CO2. One statement dealt with enhanced thermohaline circulation, one dealt with enhanced biological production, and the other found that precipitation enhancement was caused by orbital forcings. That is not proof that the temperature was enhanced by the CO2.
However, Section 6.4 at figure 6.3 shown below illustrates a rejection of this enhancement theory. The figure below shows that a rise in temperature (black line) occurred slightly before a rise in CO2 (red line), before N2O (green line) and significantly before a rise in methane (blue line). But it also shows that CO2 does not drop immediately after the temperature drops. This rejects the enhancement theory.