Grass may help keep temperatures lower, but it needs water to survive. (Photo: Emmanuel Lozano/The Republic) Todayâs question: A recent article on âhot Phoenixâ ended with effects of Phoenix’s urban sprawl creating a heat island, exacerbated by a lack of vegetation and more pavement and buildings. Years ago residents were encouraged to rip up lawns and replace grass with stones/pebbles to conserve water. Didn’t that cause the heat island? You need get up and go for a long drive and see the sights. Then you should study the Valleyâs population growth since World War II and go to the zoning offices of each city in the area to see how much land has been designated for commercial or industrial over that time and go over scientific reports on the heat absorption rates of concrete and asphalt, watered lawns, loose gravel and desert sands. Oh wait, thatâs what Iâm supposed to do to be a responsible journalist and provide you with a complete and accurate answer to your question. Well, I think we all know thatâs not going to happen anytime soon. Letâs just leave it at this: A neighborhood with great swaths of greenery may be a tad cooler than the area around it. It also will guzzle a lot of water and require a lot of fertilizer and weed killers. There are a few neighborhoods around the Valley that are graced by such greenery, but they are dwarfed by the vast expanses of concrete and asphalt that suck up…more detail