No, I would not say that we have had no effect. However, heat island, which would be an obvious contributor, has more to do with paved surfaces (heat storage) than does any immediate effect of carbon. Higher humidity rates associated with a concentrated population also must have a significant effect on localized heat storage capacity. There are figuratively a million variables exclusive of carbon that are having an effect. And then the shocker . . . . the earth has gone through periods of widespread tropical conditions alternating with arctic conditions long before the prevalence of a large industrialized population. Hmmmmm, how does one explain such outliers? Coal deposits = ancient tropical forests? Present day ice fields covering ancient tropical regions. Seems to me that the only constant is change. Temp goes up, temp goes down, temp goes up, temp goes down, ad nauseum.
As for carbon and pollution credits, these are an incredibly ridiculous notion. But someone figured out how to make a lot of money out of them, so I don't see those going away any time soon. I try to boycott companies that offer a more expensive "carbon conscious" option, be it shipping or merchandise. Just one more way to fleece stupid people out of their cash.
It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.