“the reference point for the start of the alarming decline of arctic sea ice, about the time when we were awash with warnings about the imminent ice age?”
No, we were never “awash with warnings about the imminent ice age.” That’s a bit of propaganda the denialists cooked up long after. SkS has a post, I believe:
http://www.skepticalscience.com/ice-age-predictions-in-1970s.htm