If the short-term trend was cooler temperatures, I have no doubt that the enviros would be blaming "global cooling" on industrialization. Something to think about. The issues are: is there really a long-term trend, and how fast is it playing out? If the process is slow, mankind can easily adjust. As our technology improves, I am confident that we will at some point be able to control any heating/cooling trend. In other words, rationality and development are the ultimate thermostats.
Indeed, that's exactly what they were doing back in the 1960s and 1970s. Here's a link to an excellent seminal scientific paper on climate change. (Don't worry, it's readable, especially given that it published in 1933.)
http://docs.lib.noaa.gov/rescue/mwr/061/mwr-061-09-0251.pdf
If we then had the media, politics, and technology that we now enjoy, how might we have responded? Let us not forget that 1930, 1934, and 1936 rank among the worst droughts and severest heat waves ever to strike the United States and that the term "Dust Bowl" entered into the American lexicon in 1936. The winters of the era in the politically important Northeastern states (excluding of course 1933/34) rank among the mildest in climatological history.