I imagine that the latitude matters, too. Near the poles, the sun is coming in at such an oblique angle that any given surface area isn't getting much heating effect from it anyway, so it's easier for the insulating blanket effect to be a net positive.
I only skimmed the article, but it had me wondering about the same.
There's been talk before about trying to form artificial clouds over the ocean in order to reduce warming. I'd be very curious to hear how this might relate to that. Is it possible that man made clouds could drift to the poles and make everything worse?
They can be relatively localized. Consider contrails, which with the grounding of air travel in the US after 9/11 had climate impacts that could be studied.
