Scientists pretty much agree at this point that the "global cooling" experienced in the 1970s was a byproduct of radiation from the 1940s & 50s (nuclear testing, Hiroshima/Nagasaki, etc.) blocking out a percentage of the sun's warmth, leading to a short period of global cooling.

That period is now seen by most reputable scientists as an explainable blip in the larger context of global warming.