It's just microclimates. I particularly hate the article's framing of white materials as "geoengineering", which implies that black asphalt roofs and roads are somehow not. We also know urban heat islands shift moisture downwind. So they've modeled some micro interaction that shows piecemeal application of low and high albedo surfaces can possibly result in some weird local effects on precipitation, all packaged up for misinterpretation by EPDM manufacturers.

Meanwhile everyone with a brain knows that black asphalt and roofs are hotter than white surfaces. The solution is of course stop black roofs and the bate minimum amount of roads/parking lots, not try to make everything heat absorptive in the name of equality.