Can increasing carbon dioxide cause climate change?   Richard S. Lindzen

“The title suggested for this paper (by Dave Keeling) is tantalizing for its ambiguity. At some level, the answer is philosophically trivial. After all, our knowledge is rarely so perfect that we can say anything is absolutely impossible. In connection with this question we can go a bit further, and state that increasing CO2 is likely to cause some climate change, and that the resulting change will involve average warming of the earth. However, this answer is almost as trivial as the first. The climate is always undergoing change, and if the changes due to increasing CO2 are smaller than the natural variability, then these changes will be of only modest concern except as an exercise in weak signal detection….

…. Indirect estimates, based on response to volcanos, suggest sensitivity may be as small as 0.3– 0.5°C for a doubling of CO2, which is well within the range of natural variability. This is not to suggest that such change cannot be detected; rather, it is a statement that the anticipated change is well within the range of what the earth regularly deals with. It is further noted that the common assertion that even small changes in mean temperature can lead to major changes in climate distribution is ill-founded and, likely, wrong. “

Work reported here was done cooperatively with E. Schneider, C.Giannitsis, and D. Kirk-Davidoff. This work was supported by Grant914441-ATM from the National Science Foundation and Grant NAGW 525 from the National Aeronautics and Space Administration. Ten percent of this research was funded by the U.S. Department of Energy’s National Institute of Global Environmental Change (NI-GEC) through the NIGEC Northeast Regional Center at Harvard University (Department of Energy Cooperative Agreement DE-FC03–90ER61010) and through the Computer Hardware, Advanced Mathematics and Model Physics program. Financial support does not constitute an endorsement by the Department of Energy of the views expressed in this article.

http://eaps.mit.edu/faculty/lindzen/181_PNAS97.pdf