I know there are two strident voices out there in regards to global warming. Some say "Aye"! Some say "Nay"!
I only know my own backyard. Last night the temp got down to a minus 20 degrees. That's a new record low for this date in January. The previous low was a minus 18 set in the year 1972.
The past two summers here have been unseasonably cool and totally unlike the summers of previous years when we might experience temps well above 100 several days in a row. Not that I want to see those kind of days...I actually LIKE a cool summer.
Did you know that the State of Iowa has been covered with several glacial Ice Ages, the last one at its height a mere 20,000 years ago and melting a recent 13,000 years ago. So...with glaciers retreating from a major portion of Iowa so recently, it would seem to me that we can consider weather cycling a rather recent phenomenon in terms of geological time (where scientists often speak in terms of millions of years, not thousands).
And did you know that the Northern Hemisphere experienced a Little Ice Age a mere 300-500 years ago. According to this PBS article (click here) glaciers advanced "in China, New Zealand, and Peru, and snow covered Ethiopian peaks." North America and Europe experienced disastrously cool temperatures in regards to crops and harvests.
You can read about the glaciers that covered a major portion of North America here. And more info here where you can view a small active map of the retreat of the glacial ice.