Beginning around the end of World War II, temperatures on the earth fell so consistently that many feared it was the beginning of a trend that would eventually end in another ice age. Of course, global trends take much longer than twenty years to establish themselves, so the scientific community remained divided on the issue. They realized that they did not have enough data to say with any authority that temperatures would continue to fall.
The media, however, accepted less solid evidence for proof of the global cooling phenomena and reported in a famous 1975 Newsweek article about the "ominous signs that the Earth's weather patterns have begun to change." The "global cooling hysteria" even inspired a song from The Clash called "London Calling."
Like the global warming crowd today, global cooling activists believed that man was the cause of this cooling. They believed that there were two main ways that man could influence the environment. When humanity released greenhouse gases into the atmosphere, energy from the sun would be trapped within the atmosphere, producing a warming effect. When it released smog, however, this smog would deflect rays from the sun entirely, producing a cooling effect. Obviously, global cooling activists were concerned about smog whereas today's global warming activists are concerned about greenhouse gases.
There were also some who believed that humans had nothing to do with global cooling. They believed that it was caused by changes in the tilt of the earth's axis and its orbit. This would cause less sunlight to reach the earth, making the planet colder. This was a phenomena described by geologists who believed that the earth was in the midst of or about to begin one of these periodic changes. Although they thought these changes would take thousands of years to take place, the idea that Ice Ages could be predicted and that one was coming "soon" caused a great deal of worry.
By the end of the 1970s, however, global cooling had joined a myriad of ideas that scientists have rejected over the years. They had begun to realize the importance of new greenhouse gases that they had previously regarded as harmless to the environment. The fact that temperatures stopped cooling and began warming were obviously very important to the eventual abandonment of the global cooling hysteria.
It did have a significant impact on climatology, however. It demonstrated that the scientific community did not keep as accurate records of global temperatures as it needed to be able to make any valid predictions about how global temperatures were trending. Scientists therefore began studying the subject more intently and eventually realized that the earth was in fact warming. This has given rise to our present concerns about global warming and a much better understanding of climatology and long term trends in the earth's temperature.
