While it is commendable for researchers to strive in their work toward the benefit of their fellow human beings, those investigators who nowadays promote certain exaggerated scenarios related to global warming and the so-called greenhouse effect are doing a disservice to both their science and their society.
At a recent event, the annual Climate Diagnostic Workshop in La Jolla, Calif., a group of experts gathered: more than 150 practicing climatologists from all over the world. From the papers delivered at the meeting - as well as from the corridor talk - it was clear that the overwhelming majority could see no increase in the average global temperature during the past 100 years. It was also clear that, while most were concerned about the possible effects of anthropogenetically introduced greenhouse gases in the atmosphere, few were convinced that a sound scientific basis has been established for gauging the magnitude of those possible effects.
Consider the following: Even if one were to accept that there was as much as a 0.5°C increase in global temperature in the last century - and even if it were agreed that it was totally due to CO2 - this would still lead to a predicted increase of only 0.5°C over the next 100 years. This is because the CO2 exists in a saturated state with respect to infrared radiation in the earth's atmosphere, and the temperature change due to an increase in CO2 concentration varies only as the logarithm of the CO2 concentration.
There are greenhouse gases other than CO2, of course, and their contributions must be considered as well. One difficulty is that neither the sources of these other gases nor their possible future developments have been as well studied as those of CO2. The standard procedure of most climate modelers is to introduce an accumulated perturbation due to these gases that is "equivalent" to twice the perturbation of CO2, which, in turn, would give increase to a doubling of the temperature change. However, the other greenhouse gases have characteristics that are very different from those of CO2. The chlorofluorocarbons, or CFCs, for example, are not near saturation and are strong absorbers - but future emissions will be controlled for very important health reasons associated with ultraviolet radiation. Also, many of them are from point sources and, because of the low relative volume, can be captured. Furthermore, they have a short lifetime in the atmosphere - about one tenth as long as the CO2 lifetime.
Although I know of no climate scientist who is not concerned about man's perturbation of the atmosphere, it is difficult to see - given the state of our knowledge - where the extreme scenarios of global warming come from. And the problem posed by these exaggerated scenarios of long-term global warming is most severe in that they distract us from the pressing search for knowledge on such immediately consequential matters as regional climate change, local rain and drought, the severity of hurricanes, and the strength of winds. The global increase in temperature is but a surrogate measure of what is going on - and it is of little direct interest.
An injection of funds to develop and support researchers in all aspects of climatology is greatly needed. This would be most effective at the predoctoral and postdoctoral level, and numbers of the order of several hundred would have the required impact. The needs transcend the requirements of global warming. The understanding of climatic variations and the possibility of term prediction hold economic and social values that are far above any investment we are able to make.
William A. Nierenberg is director emeritus of Scripps Institution of Oceanography, La Jolla, Calif.