Data from ice cores, tree rings etc, are specific to their locations and can also be interpreted differently depending on who is doing the analysis, and, who is paying them to do it. I would have to say that highly accurate averaged worldwide temperature data is not available for very far back in history.
We can debate whether or not climate change is real and/or caused by us until the cows come home, but we will die of old age before we know the answer. Which is why many people could give a shit less.
Extraction and combustion of fossil fuel is extremely polluting and destructive (particularly, but not limited to, coal), that is all the reason I need, to at the very least, endorse alternatives that hopefully are cleaner. For me, it has little to do with climate change, even though the impacts from that will be even more severe in the end. Carbon credits are just ridiculous. Reduction of use is the most effective.
A man we will not name goes into a movie theater and sits down. Halfway through the show he gets the shakes and decides to light up. Quickly his smoke cloud pervades the theater, and just as quickly the “climate” in the theater changes! from everyone enjoying the picture, to everyone yelling at this person and throwing popcorn at him.
Funny how not that long ago almost everyone in the theater would be smoking, and most of them believed it would have no detrimental health effects.