The following article is an excellent summary of how and why the current concept of man-caused (anthropogenic) global warming began. The basic premise is the fear of global warming and the control of it by limiting carbon dioxide emissions is really about limiting world population growth. I'm not sure that all or even most advocates of the man-caused global warming agree with the population control connection, but surely many do.
Where the Global Warming Hoax Was Born
By Marjorie Mazel Hecht
“‘Global Warming’ is, and always was, a policy for genocidal reduction of the world’s population. The preposterous claim that human-produced carbon dioxide will broil the Earth, melt the ice caps, and destroy human life, came out of a 1975 conference in Research Triangle Park, North Carolina, organized by the influential anthropologist Margaret Mead, president of the American Association for the Advancement of Science (AAAS), in 1974.”
Full document here [PDF, 1MB]