The 'greenhouse effect' (which was the umbrella term for what is now called climate change) was widely discussed in the 80s and 90s and taught in schools, at least in Australia.
As a child I learned that many metropolitan cities would be underwater by the year 2000.
The science confirming man made climate change was presented in the 1970's, many have known since then we are the cause of the earths warming. It has been settled science for the better part of 30 years. It has been taught in schools around the world since the mid 1980's as part of Science and Geography Curriculums including some of its known impacts such as the rise of sea levels.
I decided to do a Google newspaper archive survey just to see what people were saying back then. I'll be honest, the articles seem pretty close to the mark from what I see.
For instance, a 1988 article says scientists warn that pollutants already have committed the planet in "30 years to 50 year to its highest temperatures in 10,000 years"; in 2017 I would say that (based on our reconstructed temperature estimates) this prediction is likely (https://en.wikipedia.org/wiki/Temperature_record_of_the_past...).
I don't doubt that there were some people that projected overly pessimistic doomsday scenarios of flooded cities by the end of 2000 (though to be honest most of the articles I'm encountering more warn of 2100), but for me this is actually is an interesting confirmation; even 30 years ago, the scientists had a model in place that has proven to be way more resilient than some of the deniers would have it.
As a child I learned that many metropolitan cities would be underwater by the year 2000.