I don't think many people were under the impression Al Gore was having a real public conversation. His books and movies fall squarely into the "alarmist" category.

In what sense?

Didn't he say we would all be underwater by 2010 or something? I didn't see the movie...

If he did, would you mind sourcing it? Until then I don't see a reason to believe you, as you yourself say you didn't watch the movie.

He said sea levels could be 20 feet higher in the near future. Which could only be right if we’re talking hundreds of years…

Hundreds of years is kind of the near future with respect to the ~300,000 years we've existed (H. Sapiens, and tools) and the ~30,000 years since we started to 'civilize' (art, descriptive cave paintings) even relative to agriculture (12,000 BP)