Ripping out your lawn may have a greater impact on the environment than you think. There are consequences to removing grass, both good and bad.
Los Angeles homeowners have been on a mission. In the last year, water-thirsty lawns have been replaced with drought-tolerant landscaping options at a rate never before seen. Across the city, tens of thousands of lawns were ripped up in favor of gravel, artificial turf, decomposed granite, and a wide range of drought-tolerant and native plants.
Of course, the water-saving benefits are tremendous! According to experts, Californians are facing the worst drought in 1,200 years, and every water-saving measure should be exploited. But some eco-conscious experts wonder if there might be some unintended consequences to eliminating so much green space. (Read about California’s Tree Disparity)
Gardens and lawns act as air conditioning for Los Angeles, which is only getting hotter with climate change. Plants and trees provide shade and give off moisture to cool the air. If L.A. homeowners continue to remove moisture-producing vegetation, do we also loose the cooling effect?
Geophysical Research Letters recently published a paper by University of Southern California post-doctoral research associate, Pouya Vahmani, and USC civil and environmental engineering professor, George Ban-Weiss, which analyzes what would happen to the city’s overall temperature during the month of July if every lawn in Los Angeles were replaced with drought-tolerant plants.
If every lawn in Los Angeles was comprised of drought-resistant native plants, daytime temperatures would actually increase 3-4 degrees due to decreased irrigation. That’s because water stored in grass helps lower air temperatures. No grass, no cooling effect. So should we reconsider terminating the turf?
Fortunately, the study wasn’t all bad news. They also found that replacing all lawns in L.A. would decrease nighttime temps up to 5.4 degrees. The overall difference suggests eliminating lawns would ultimating produce a cooling effect for the environment. The finding surprised even the researchers.
“We hypothesized that our model would predict daytime warming, but we did not anticipate the nighttime cooling signal,” study coauthor George Ban-Weiss told the paper. “In retrospect, it makes sense that reducing soil moisture would change the thermal properties of the soil and surface-atmosphere coupling in this way.”