>You can’t use sci-fi to draw conclusions about anything except the culture in which it rises.
I can draw conclusion about culture of that age - just like I can draw conclusions of my own on this culture of modern era, which sure will also raise questions to future generations. However my conclusions about human behaviours has nothing to do with the volcanic activity, that will prove theory of Global warming wrong.
My main point here is that Sid Meyer during the creation of his game probably had no idea about those early global warming papers and "research" that you are so eager to point in that publication from earlier times - including earlier centuries, but clearly the idea about global warming was in the air in 1980s for completelly different reasons. Since I did not live in US, I can't recollect any talks about global warming in 1980s - this really exploded in my region only in 2000s(not much after it became a thing in US), when effects of global warming could be seen and when Al Gore was pioneering the usage of this question to gain political power.
>Explain.
The wiki part is not that interesting as background story of childish - even Hitler Nazi behaviour of scientists, where the one who provided that chart(without any proof) and who later could not admit that he was wrong about calculations(that this whole model was based upon) and who caused grief to anyone else who opposeed him.
https://en.wikipedia.org/wiki/Hockey_stick_graph
>The other 10% is the problem.
Providing numbers like these are what I call a religious belief.