No cause and effect link shown
While he does not present much in the way of data, John Smol does mention its importance in the last paragraph, saying "Opinions and wishful thinking do not mean very much in science - data and evidence matter." It is in this spirit that I write what follows.
Climate researchers frequently claim that increasing atmospheric CO2 levels (caused by man) are causing earth's average temperature to increase. Claims like these are not accurate. What is really being demonstrated here is correlation between atmospheric CO2 and earth's average temperature. This is not the same thing as demonstrating cause and effect.
In a famous example which demonstrates the difference between correlation and causation (J. Neyman, Lectures and Conferences on Mathematical Statistics and Probability. Graduate School, U.S. Department of Agriculture, Washington, 1952, pp 143-154) the number of storks per 10,000 women is shown to correlate very well with the birth rate of children per 10,000 women in 54 countries. However just because there is a high degree of correlation between the number of storks and the birthrate of children does not mean that storks cause children to be born. In saying that people are causing earth's temperature to increase, climate researchers are similarly confusing cause and effect with correlation.
Climate researchers use very complex computer models to show that mankind is responsible for rising temperatures. However, in order for these models to be used to demonstrate cause and effect, they must accurately model climate. Unfortunately, this is not the case. In a recent paper ("On the determination of climate feedbacks from ERBE data", Richard S. Lindzen and Yong-Sang Choi, Geophysical Research Letters, Vol. 36, L16705, doi:10.1029/2009GL039628, 2009), the authors used 16 years of satellite observations to show that 11 different climate models all disagreed significantly with the measured data. In fact, the climate models are so wrong that their predictions go in the complete opposite direction from the measurements. I know from my own 30 years of computer-modeling experience that when any computer model fails this badly, it cannot be used reliably, and must be scrapped or at least completely overhauled.
Another example that climate research is unfinished can be found in another recent paper ("Variable solar irradiance as a plausible agent for multidecadal variations in the Arctic-wide surface air temperature record of the past 130 years", Willie W.-H. Soon, USA Geophysical Research Letters, Vol. 32, L16712, doi:10.1029/2005GL023429, 2005). In this paper, Willie Soon, who is a Harvard astrophysicist, shows that earth's temperature correlates much better with the sun's changing radiation than with atmospheric CO2. While Soon does not demonstrate cause and effect, he at least provides an alternate and plausible area of research to explain why earth's temperature is increasing.
In summary, the climate debate is far from settled. There are fundamental issues which remain unresolved, with the distinction between correlation and cause and effect among the most important of these.
Bill Korchinski, Sc’75
Santa Barbara, CA