Before CO2, you had pollutants like NOx, which were toxic pollutants, and CFCs, which were pollutants but not toxic. CFCs were considered pollutants because they damaged the Earth in a way that would have a negative impact on human health, but non-toxic because their harm was not directly effected on the human body. CO2 would be the kind of pollutant that CFCs are. (CFCs are toxic in high concentrations, but the mechanism of their harm when released into the environment is not toxicity.)
While the effects on CO2 may be significant and possibly beneficial, I think we should focus on particulate matter, CO, NO and other pollutants directly poisonous to the human body.
"CO2 is not a pollutant, any more than water vapor is."
CO2 actually is considered a pollutant by the EPA. There are lots of things that are 'natural' but that are still pollutants. For example, fine particulates are considered a pollutant because they cause cancer. Thus construction equipment is not allowed to vent unlimited amounts of diesel fumes, even though much of what is released is basically the same as the stuff that already occurs to a small extent in the natural environment.
Technically speaking, carbon dioxide, which is what I assume you refer to by carbon pollution, is not a pollutant. It is a non-toxic inert greenhouse gas, used by a very large quantity of organisms as an exchange gas.
An alien society may produce pollutants which last a million years. Plastics can last millions of years.
Sufficient pollution could cause climate change severe enough to keep all kinds of things airborne for who knows how long. We are constantly surprised by what we learn about other worlds. It is silly to me to presume that anything we know about Earth pollution will be a given on a planet from another star system.
CO2 is one of the few pollutants I don't care about having in my lungs. There's already a bunch in there, and any additional amount that comes from external sources is going to be trivial compared to what I make on my own. CO2 is dangerous globally but essentially harmless locally.
Right, it isn't. In fact, many potent greenhouse gasses such as many fluorocarbons are the least toxic of all chemicals (which was one of the their main virtues and why they were used).
Their problem is not toxicity but greenhouse warming - an altogether different mechanism.
Uh, that's not true at all. CFC's that most people are concerned with emitting aren't necessarily greenhouse gases, and the greenhouse contribution is not really a primary concern with them.
The primary concern is that many of them are catalysts with very very long active lifespans. As a catalyst (not a consumable reactant), a single CFC molecule is capable of destroying hundreds of thousands of ozone molecules in the upper atmosphere (or more). It's the catalytic nature that makes these things problematic and accumulative even in small amounts. The accumulation of these long-lived gasses would be measurable if everyone were blasting their laptop once a day, which is precisely why a number of them are banned completely. The ones generally used now are relatively better, but there is still plenty of reason to avoid emitting them if possible.
Cigarette smoke isn't comparable when it comes to environmental concern, nor are most common combustion byproducts. Those definitely cause concern for different reasons, but aren't directly comparable to environmental concerns raised by CFCs.
One needs to distinguish carbon dioxide and methane from your run of the mill toxic chemical pollution. It isn't a linear sum of "pollutants" but different substances with different effects.
And the thing is that these are actually harming the people who are near the area where they are disposed, so the harm is more direct.
CO2 is more like a global problem, so not as worrisome for the local population.
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