The cooling myth is pulled out frequently by deniers.

What's behind the myth?  

Back in the 1970s when the world was burning a lot of coal and not doing essentially nothing to trap problem emissions (remember acid rain and dying forests?) a small number of papers were published stating if this continues and increases we could see "global dimming".  The pollution clouds would block enough sunshine to allow the Earth to start cooling.

Made sense.  We saw some global dimming, and some decrease in crop growth, following WWII as coal plants roared into operation as Europe and Asia rebuilt.  The science was solid for man made global cooling.

Thing is, we put scrubbers on enough of our smokestacks to keep pollution clouds from cooling things down.

Humans could have cooled down the planet, but we made some technological changes and didn't.  Now we need to make the needed technological changes to slow down and stop human caused warming.