It didn't "confirm" it was caused by man, as it didn't set out to and doesn't claim to.
Nevertheless the collected data seem to indicate a steady increase in temperature. This has coincided with increased emissions of CO2 (while many other factors remained constant, or more precisely didn't vary enough to allow anyone to claim correlation). This of course does not mean that it's _caused_ by the increased emissions of CO2.
But if my belly starts aching I look at what I ate that others didn't. And if I ate something that others didn't (say a dodgy kebab) and I feel bad and they don't then of course I can't claim I feel bad because of the kebab. But I'm sure not going to have the same kebab next time. I don't wait for a double blind study done on a statistically significant sample to confirm to within some statistical error that the kebab is indeed bad.