Global cooling was a conjecture during the 1970s of imminent cooling of the Earth’s surface and atmosphere along with a posited commencement of glaciation. This hypothesis had mixed support in the scientific community, but gained temporary popular attention due to a combination of press reports that did not accurately reflect the scientific understanding of ice age cycles, and a slight downward trend of temperatures from the 1940s to the early 1970s.
http://en.wikipedia.org/wiki/Global_cooling
In the 1970s, when I was an earnest young science geek, I tried to explain to my grandmother the coming ice age caused by human pollution. I just couldn't get her to understand the gravity of the situation.
She told me that when she was a girl at the turn of the last century, the newspapers were reporting a coming ice age. This was followed by the heat and dust bowl of the early 20th century. After a period of slight cooling, the "end of the world kooks" were was back to calling it an ice age.
Now I am explaining the same phenomenon to my children. When the weather is warm, end of the world kooks call it global warming. When the weather is cold, end of the world kooks call it global cooling.
Either way, it is all Bush's fault.