I have also vaguely noticed that it started being called pollution sometime this century. "Huh, that's new", I thought. Not particularly surprising, though. Of course that timespan is almost 30 years, so my concept of recent change might be getting stretched.

But yeah, more familiar pollutants are dirty or caustic or radioactive, and chew holes in things or give you lung diseases or poison the wildlife, things like that, so it was a little jarring. Though I suppose we had CFCs, they didn't do anything directly harmful either.

If it was always this way, explain why the IPCC's seminal report on climate change uses the phrases "CO2 enrichment" (rising CO2 levels) and "air pollution" as if they're two different categories?

> 2.2.4 Consequences of CO2 enrichment and climate change for natural terrestrial ecosystems could be modified by other environmental factors, both natural and man induced (e.g. by air pollution).

Help me parse this according to your understanding that "CO2 was an air pollutant 30 years ago." If CO2 is a subcategory of "air pollution," then it makes no sense to list "air pollution" as an example of "other environmental factors." It wouldn't be grammatical. The report uses this basic sentence structure, referring to "CO2 enrichment" as one thing in distinction to "other environmental factors" including "air pollution" several times. Explain to me how that's consistent with your position?