Comment by wishfish
2 days ago
I'm thinking about light colored roads that seem to be made of concrete. See them here and there. Seemed to be more of them when I was a kid.
Wonder if that would make a substantial difference? Much brighter than asphalt but not bright enough to bother drivers.
I was thinking you could potentially engineer them to reflect IR light, but I feel like dust and dirt would probably quickly eat into the effectiveness. The question is whether it'd really make a difference on a global scale at all.
There are materials that do what you're looking for surprisingly effectively, staying many degrees sub-ambient even in direct sunlight. (See https://onlinelibrary.wiley.com/doi/full/10.1002/eom2.12284 for example). But a roadway is a really difficult use case for a surface coating. With something like 50% of the surface area of many American cities being road or parking, there's a lot of potential room for effectively mitigating the urban heat island effect, but I think roofs are a better target. They don't have cars sitting on top of them blocking sightlines nearly as often.