It’s hot in Houston, I can tell you from first-hand experience. Triple-digit heat is here to stay until the fall. The city’s concrete sprawl is making things worse, turning it and the surrounding area into an urban heat island. A report from Climate Central ranked Houston as the fourth-worst urban heat island, behind New Orleans, Newark, and New York. These head islands are in the news more than ever as we see record temperatures around the world. Impermeable surfaces, lack of greenery, tall buildings, and heat created by human activities makes cities hotter than other areas in outlying regions experiencing the same weather.
Houston is tackling the problem head-on, setting an example for other cities to follow. The city of Houston is roughly 13 degrees hotter than the surrounding rural areas. Experts predict the average number of days with a heat index above 105 degrees to increase from 10 to 74 by 2065. As the world gets hotter due to climate change, understanding heat islands is key to saving lives. Recently 75 community scientists endeavored to create a heat map of the city using specially-designed thermal sensors attached to cars and bikes. The Houston Harris Heat Action Team (H3AT), a collaboration between The Nature Conservancy of Texas, Houston Advanced Research Center, the City of Houston, and Harris County Public Health partnered with Lowe’s and Shell on the project that aims to understand one of Houston’s most dangerous climate-related impacts. The project was the largest, single-day, community-led heat mapping effort in history, serving as an example for other cities to replicate.
“Houstonians do not prepare for heat like we prepare for hurricanes, but we should,” said Mayor Sylvester Turner. “Houston is getting hotter, and we need science and data to help identify where the greatest impacts are, so we can keep Houstonians safer and our City more resilient.”
Heat is actually the most deadly form of weather in the world. Earlier this summer hundreds of people lost their lives during devastating heat waves in the Pacific Northwest, which saw Portland hit a whopping 116 degrees. The EPA estimates that more than 1,300 deaths per year in the United States are due to extreme heat. More than five million people die each year due to extreme temperatures, with deaths from heat rapidly rising.
The good news is heat islands are a solvable problem as long as you know where they are. That’s why Houston is so eager to map its heat island effect. Once they know the hot spots, solutions can be implemented. Planting trees is one of the best defenses against heat islands. Not only do they provide shade, but they also increase biodiversity, increase access to greenspace and help clear the air (Houston’s smog is its own issue). Green rooftops can also help lower heat island effects. Vegetation is key to shading, deflecting radiation, and keeping the atmosphere moisturized. Knowing where the city lacks canopy will help officials target the hottest areas.
“Ultimately, the urban heat island effect can impact many aspects of human health and well-being,” said Dr. Meredith Jennings, Ph.D., Postdoctoral Research Scientist. “This study will be an important first step to help communities understand urban heat islands, guide policymakers on next steps, and move forward with science-backed solutions to improve quality of life.”
In its final report, H3AT deployed 84 volunteers along 32 routes, taking 232,729 measurements. The highest temperature recorded was 103.3 with a 17.1 degree differential across the city. Hot spots included areas with homogenous apartment designs, wide parking surfaces, and little vegetation. Roads and highways were noticeably harder. Green spaces clearly helped to mitigate the heat. The completed heat map is overlaid with economic maps revealing vulnerable communities to better understand the most acute impacts of heat on those who may not be able to afford cooling. For residents, the results sound obvious, but with the data finally in hand, solutions can start to be implemented. Studies show to mitigate the heat island effect, Houston needs to plant 2.4 million trees to account for the city’s severe lack of canopy cover. Only 18 percent of Houston is under shade. Activists and city leaders are already working to change that.
Efforts to study Houston’s heat island effect are part of a larger initiative led by CAPA Strategies and supported by the National Oceanic and Atmospheric Administration’s Climate Program Office, which helped to fund the project. CAPA is working on similar studies are underway in Los Angeles, San Jose, Atlanta, New York, and Boston.
Mitigating heat islands is becoming a critical part of urban policy, Climate Central estimates 83 percent of the U.S. population lives near an urban heat island. At the Tokyo Olympic Games, athletes have complained have abnormally high heat. Unsurprisingly, the city of nearly 14 million residents is an urban heat island. Temperatures of 93 degrees make the Tokyo games the hottest Olympic games on record. Russian archer Svetlana Gomboeva was treated for heat exhaustion at the start of the games, not long after Tennis star Novak Djokovic made public statements about the heat, saying the ‘hardcourts absorb the heat, it stays trapped in there.’
The heat island effect means our cities are most vulnerable to rising temperatures from climate change. Scientists at the EPA have linked climate change to higher temperatures and longer, more severe, and more frequent heatwaves. Lowering the heat island effect will lower electricity demand, air pollution, greenhouse gases, and a variety of other health impacts. As we’ve all seen, heat can be deadly. Floods, tornadoes, hurricanes, and other extreme weather events may garner the majority of headlines, but none are as deadly as the slowly rising temperature. Fighting climate change will require adapting our urban environments to mitigate the worst effects. Whether living in Houston, New York, Tokyo, Sydney, Cairo, or London, urban residents across the globe are the most vulnerable to rising temperatures. Resilience means treating urban heat islands like the public health crisis they are.