They sampled red-green ratios from various painters, compared it to historical pollution data and found a correlation.
Good God. Seriously? Really wonkey_monkey? You're willing to give these idiota the benefit of the doubt because... they found a correlation? I know what happens next: The correlation becomes a model, the model predicts utter doom for mankind, possibly, but first more money is needed to fund further research!
They should be fired for brining science into disrepute. I bet their "correlation" doesn't have any error bars because, well, they have no idea how accurate their measurement is.
and what we've observed is the warming that was predicted
Don't be silly. What's happened is scientists have absolutely no clucking clue what caused the warming, or indeed the cooling, or indeed the warming before that or the cooling before that, but nevertheless will hoover up huge grants for their research institutions by pretending they do.
Many scientists concurred, he said, that recent heatwaves and floods were evidence of climate change already on the march
What a load of utter shite.
Living on Earth may be expensive, but it includes an annual free trip around the Sun.