Peterson, Thomas & Connolley, William & Fleck, John (September 2008). The Myth of the 1970s Global Cooling Scientific Consensus. American Meteorological Society. http://ams.allenpress.com/archive/1520-0477/89/9/pdf/i1520-0477-89-9-1325.pdf
The hypothesis was proposed over 100 years ago, and has been a focus of serious research since the 1950s or so, and has been the consensus opinion of climate researchers for about 20 years now.
The fact that most of the public kept their heads in the sand* through this process is irrelevant. Science does not progress by going back to square one at the request of every ignoramus who decides that he wants to passively investigate some phenomenon as a part time hobby.
This post was inspired by the discussions at Libertarians for Junk Science, and is related to my post at Freedom Democrats The Politicization of Climate Science.
*with the help of plenty of profiteers driven by ulterior motives