| Cool It |
Although we do not know which direction the sun will fluctuate
over the coming years - warmer or cooler, it is clear which direction we should hope that it will fluctuate. If the Earth becomes warmer than humans think desirable, there are several means by which human activity can cool the Earth. If the Earth becomes too cool, however, there is no known practical way to generate enough energy to warm it.S. S. Penner,
Journal of Clean Technology and Environmental Sciences 3, No. 3/4 (1993), who works at the University of California at San Diego and is one of America's most brilliant engineers, has estimated that the conversion of about 2% of the jet fuel in commercial jet airliners during a four-year period into particulate forms similar to those emitted by volcanoes could cool the Earth by about 3 ºC. Extrapolating to expected air transport in the year 2050, he estimates that this could be done by the same means in one year rather than four.Professor Penner estimates the cost of this cooling method based upon either conversion of ordinary jet fuel or the use of a new jet fuel into which coal has been blended. He proposes that the method be developed by careful studies of volcanoes - which currently cool the Earth in the same manner. His rough current estimates are that 1.5 ºC of cooling with coal blended fuel would cost less than $300 million. The particulates produced would shield the Earth from a part of the sun's radiation - so small a part that people on the Earth could not see the shield or personally detect its presence.
Other means of injecting this shield into the upper atmosphere have also been suggested such as the use of naval guns to shoot it into the atmosphere. In any case, we can be certain that this method would work because volcanoes frequently cool the Earth in the same way.
We can only hope that the sun's activity tends toward the warm side. In addition, however, mankind can also bias human activities toward those that might help in this warming. Although carbon dioxide release is apparently not especially promising in this regard, any effect that it does have will probably be warming rather than cooling.
Carbon dioxide release from coal, oil, and natural gas is beneficial because it increases the plant and animal opulations of the Earth. It is also beneficial because any effect it eventually might have upon Earth temperatures would be toward warming - the desirable direction if mankind is to have an opportunity to tune the Earth's thermostat. We have means available to cool the Earth, but we have no means available to warm it. If our climate becomes too warm, human engineers can fix it. If, on the other hand, natural forces were to lead us into a new ice age, our engineers have no means available with which to counteract this.
Human engineers have available a low cost air conditioning cooler than can be applied to the whole Earth. They do not, however, have available a heater. Therefore, we should bias all of our activities toward warming in case the sun becomes cooler.