Well since CO2 is a very very negligible percentage of the atmosphere, and since it has been proven time and again that all of the models about global warming were 100% wrong, and since I just happen to know that 50% of 100% is a 50% reduction over what would have happened if the CO2 did not initially absorb said IR.... I'm gonna take an wild guess that the amount of change the increase in C02 has caused probably can't be measured with any certainty.
You should probably note that CO2 is not the only part of the atmosphere that can absorb IR. Thus, from my engineering, statistics, and math background I find it odd that global warming models relied upon increases in CO2 to have such a dramatic effect on the mean temperature. Seems to me it would be more of a no-op given the small percentage of CO2 compared to all other greenhouse gases, like water. But if you have to make me guess what it does.. I'd say CO2 probably does what H20 does in the atmosphere.... it causes global cooling. Everyone knows it's cooler under a cloud than it is under direct sunlight. The question isn't even worth arguing about.
All you're proving is that a little bit knowledge is a dangerous thing. No one who knows anything about science would claim that something is 100% wrong. Then you go and admit that you're going to take a wild guess?!?! You might as well have said "now I'm going to talk out of my ass".
Anyone who knows the subject knows CO2 isn't the only substance to absorb IR, so don't think you're suddenly enlightening anyone. As a matter of fact, any rise in temp that does happen would lead to more H2O in the atmosphere sand even higher temps, i.e.positive feedback. Then you go and make a guess and since you don't really understand the topic, guess WRONG. H2O can lead to cooling because of cloud formation. CO2 doesn't form clouds. What's not worth arguing about is the level of your understanding. Anyone in the know would have to admit it's near zero.