An Urban Heat Island (UHI), found in metropolitan areas, is when the city temperature is considerably warmer than the surrounding rural areas, due to human activities. In these areas, the temperature is often much higher at night, and the effect is more pronounced during the summer and winter. Urban Heat Islands are caused by dark or massively solid surfaces, which absorb/collect heat, then release that heat at night; asphalt, concrete and tar are good examples—think of large paved parking lots, tar and gravel roofs and concrete arroyos and buildings. A lack of vegetation is another reason for UHI effects: with fewer trees, cities lose essential cooling effect and valuable shade; and the removal of carbon dioxide, created by the trees, adds to the temperature rise. Besides the increase in temperature, UHI’s can alter cloud patterns and trap particulate matter below cooler layers, creating pollution. UHI’s increase the demand for energy—air conditioners run longer—which costs more, and creates more waste pollution. An example of the Urban Heat Island effect is the weather forecast: notice the temps up & down the Rio Grande Valley—the Metro temperature is often higher than areas north or south.
Planting more trees and vegetation, which provide shade and emit CO2, can combat the Heat Island effect. White rooftops—rubber membrane/TPO roofs—reflect heat and minimize if from absorbing into the structure. Parking lot surfaces can be made from crusher fines or turf grid, above, instead of asphalt, and should have vegetation anywhere there are not parking spaces, to minimize heat absorption, and so no spots are lost to the greening.
What does this have to do with Petroglyph National Monument?
Petroglyph National Monument is a 7200+ acre dedicated greenspace on the western edge of the city; as growth continues west, the greenspace will become more valuable. It’s a natural buffer zone and wild urban oasis. At Petroglyph, the lush monument mesa-top grasslands & canyons already absorb CO2 and use the sunlight & heat to create the myriad plant & animal life found there, while producing oxygen. The Open Space allows for winds to circulate the fresher air into and around the city, mixing with the hotter UHI air.
At Petroglyph, there will not be heat-absorbing asphalt parking lots and large dense concrete buildings to store then emit heat at night; the vegetation will help keep the temperature more stable during the hotter months. From NPS: “This entire area, including the volcanoes, mesa top, arroyos, canyons, cliffs, and surrounding views,is part of a living cultural landscape.” The MetroABQ is lucky to have this dedicated greenspace.