Anyway...had to respond. You shouldn't even have to wonder about whether CO2 could be a pollutant or not. It isn't, can't, never will be. It's a trailing indicator of global climate shifts, not a leading indicator. All of the modern "science" that points to CO2 as a cause of anything is easily falsified, because it's science that is chasing a lagging indicator that itself is chasing the actual cause. (Not to mention the fact that the whole "global warming" issue has given a lot of politicians a lot of power and control over the unaware populace who hasn't ever taken the time to investigate the issue for themselves, or look for evidence contrary to the political agenda.) If there is any indication lately, the fact that we are entering a multi-decades long solar lull and the impact it's had on this recent winter should be of greater concern. The recent "solar maximum" was a rather pitiful one in the grand scheme of solar peaks, and winter couldn't wait to crush the 2013 summer with some of the largest flooding (globally) on record, and some of the coldest cold snaps in decades. If your sick and tired of this winter...just wait until it's 55° during the heart of summer and -45° during the heart of winter, and your energy bill skyrockets to become your primary expenditure next to your mortgage... (Of course, if/when that happens, I'm sure someone will figure out a way to blame humanity for causing it all... )
It's a "greenhouse gas", if you want to get technical. Thanks for weighing in though, you and I are in agreement on issues like these. (An even stronger greenhouse gas is methane...not that you didn't know.)
It is a greenhouse gas. The fallacy is in the notion that the greenhouse effect caused by such gases is infinite. It is not. The greenhouse effect has it's limits, the warming caused by such gases has an asymptotic relationship in terms of gas volume to effect ratio. BTW, the single most powerful "greenhouse gas", by a MASSIVE margin, is water vapor. The only reason CO2 has been demonized is is radical environmentalists couldn't find a way to demonize water vapor. ;P I'd also note that methane is also a significantly more powerful greenhouse gas than CO2. As far as CO2 goes, given it's minuscule ratio in our atmosphere, has an impact on global temperatures that is effectively "noise" relative to H2O and CH4.
I had already mentioned methane. I think the "greenhouse effect" of methane is supposed to be 4x what CO2's effect is. Interestingly, during the reign of the dinosaurs, it is thought that methane levels in the atmosphere averaged much, much higher than they are today. This might be the reason dinosaurs dominated for as long as they did, because they had evolved "airsacks" in their hollow bones that expanded their lung capacity, the same way many bird species have done since then. This allowed them to take in much more air when they breathed, allowing them to collect more oxygen out of that air, that was so polluted with methane. Thus they grew to be huge animals, while mammals remained small. The methane is thought to have come from a very large caldera that erupted in Siberia, over millions of years...amongst other theories. That is thought to have contributed to the first mass extinction, killing about 90% of all life on earth, about 400 million years ago. This was about the time "Pangea" formed. The dinosaurs supposedly didn't come into existence for another 150 million years after this caldera eruption, but the methane remained throughout much of their existence, up to 65 million years ago.
Another interesting theory about the comet or asteroid that is thought to have killed them. Sol (our sun) kind of bounces up and down like a ball, as it revolves around the galactic core. Every 30 million years or so, it passes through the more densely populated "center" of whatever part of the galactic arm it happens to be in. The pull of gravity from other nearby stars, is thought to grab large comets from the "ort cloud", and fling them into the inner Solar system. We're due for another one soon...