We were taught about climate change in the first grade in the early 80's with some fairly graphic imagery (think gas masks and deserts). More of the focus was on ozone depletion and acid rain. I don't remember any of it being political or controversial until I was in high school in the 90's.

I was taught about greenhouse gasses in 6th grade science. (In the 1980's)

I think "this" in this context refers to profiting off externalities.

I remember first learning about it in elementary school in ~1997.