CO2 can be pollution while still allowing plants to grow, plants use CO2 in their growth cycle, if you didn't know, they don't use other greenhouse gases to grow.
Page 9 lists CO2 as the first item in a list of greenhouse gases. I don't want to spend all day read this 37 year old report.
In what world are greenhouse gases not air pollutants?
For example, on p. 55.
> "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)"
That clearly refers to "air pollution" as an example of "other environmental factors"--something different from "CO2 enrichment" (rising CO2 levels). The report uses the same terminology on pp. 88 and 97. Throughout the report, it treats "greenhouse gasses" as it's own category that can interact with "air pollution"--but is different from air pollution.
Greenhouse gas refers to any type of gas that makes up our atmosphere. Air pollution are substances entering the atmosphere that degrade air quality and human health.
Therefore air pollution is always going to be a greenhouse gas, but not every greenhouse gas is going to be air pollution.
CO2 is the principle man-made GHG that all the others are compared against. CO2 is what the IPCC refers to as long-lived climate forcer, which are gases that have a warming effect on the scale of decades, fitting the definition of air pollution.
CO2 is a pollutant and has been for as long as humans have been pumping out tons of it into the atmosphere.
This GHG is emitted (alongside methane, by the way), by humans, in such quantities that it severely impacts the thermal balance of the planet, and threatens an extinction-event comparable to what only large asteroids are usually capable of.
It is only in the post-truth society of right wing anti-climate influencers that apparently someone tries to redefine the terms to exclude it.
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.
> 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?
It has been a pollutant as soon as it has started to be emitted at large scale through combustion, in particular of fossil fuels.
People who deny it are usually very brain-washed by far-right/alt-right propaganda, which tries to hammers into their brains that "it's just the same stuff that you exhale when you breathe".
They don't understand (or rather, they haven't been told!) that the scales are incommensurate.