> I’m not sure: when I was in high school / university it was well understood that places like Florida would be under water and unlivable by now.

I don't doubt that is your recollection, but nobody back then was predicting it would happen in 20 years. The time frames given were much longer. But, the vibe was definitely that we need to wake up and do something right now, because by the time climate change hits real hard it will be too late to avert the calamity.