Space station instrument can help cities battle extreme heat

NASA experiment could inform health-threatening urban heat mitigation made worse by climate change. Readings just after sunrise showed areas of central Houston and near roads were much warmer than the outskirts of the city.

This ECOSTRESS image shows land surface temperatures in the Houston area on June 20, 2022 at 6:29 a.m. Central Daylight Time. Hotter man-made urban surfaces near downtown and roads and highways appear red and orange. Clouds, which are cool relative to the ground, are shown in blue and labeled in the image. NASA/JPL

Unprecedented heat waves hit Texas as well as other parts of the United States and part of Europe this summer. According to state climatologist John Nielsen-Gammon, daily maximum (daytime) and minimum (nighttime) temperatures are up about 1.5 to 2 degrees Fahrenheit from 20th century averages across Texas.

“It’s a long-term trend, and this summer is already hotter than that,” he said. “We set daily hottest minimum records statewide, as well as daily maximum temperature records.”

According to research organization Climate Central, average summer nights have warmed by 2.5 degrees F in the contiguous United States since 1970, with 40% of the 246 US sites analyzed by the group having seen average summer nights. warm up by at least 3 degrees F. In July, temperatures in the UK exceeded 104 degrees F, the highest temperature on record there. Extreme temperatures have also broken heat records in Spain, Portugal, France, Germany and other countries in Europe, where the vast majority of homes are not air-conditioned.

This kind of heat is miserable, of course. It can also be deadly.

Urban heat expert Anamika Shreevastava, a NASA postdoctoral fellow at the agency’s Jet Propulsion Laboratory (JPL) in California, says extreme temperatures are expected to be the number one weather-related killer in the United States, in especially in urban areas, due to heat island effect.

Urban heat islands occur when natural land cover, such as vegetation, is replaced by dense concentrations of pavements, buildings, and other surfaces that absorb and retain heat. This can make urban areas typically 10 to 12 degrees warmer than surrounding land, she says.

The effects of this heat are compounded when temperatures do not drop sufficiently at night. Climate Central reports that summer minimum or nighttime temperatures in the United States have warmed almost twice as fast as summer maximum temperatures.

“Our bodies need an opportunity to cool down and recover from extreme heat, and when the nights are also hot and people don’t have access to air conditioning, it puts prolonged stress on the body. “, explains Nielsen-Gammon.

He notes that the risk is particularly acute for the elderly. Health researchers have also linked higher nighttime temperatures to a higher risk of death for vulnerable people with conditions such as heart disease.

People living in poorer neighborhoods are at greater risk because these areas tend to have fewer air-conditioned homes and less canopy to provide shade, and because many residents don’t have cars and have to walk on hot sidewalks to access work and perform essential activities such as shopping for groceries.

The Ecosystem Space Thermal Radiometer Experiment on the space station, or ECOSTRESS, could help cities identify literal hotspots and target their efforts to deal with extreme heat. The International Space Station instrument was designed by JPL to record soil surface temperatures and identify thresholds of water use and water stress in plants. It can also document patterns of heat absorption and retention by floor surfaces.

Ground temperatures are higher than air temperatures during the day, and streets are often the hottest places due to dark asphalt pavement – dark colored surfaces absorb more heat from the sun than colored ones. clearer. Asphalt absorbs up to 95% of solar radiation and retains this heat for hours after sunset.

ECOSTRESS produces high-resolution thermal infrared data in at least three spectral bands, creating images that provide a high level of detail, says Shreevastava. “It can actually distinguish between the temperature of the road and the temperature of adjacent parks and display features such as parking lots and green spaces. You can clearly see how much warmer the roads are.

The ECOSTRESS instrument took an image of ground surface temperatures in the Houston area as the space station passed overhead on June 20, 2022 at 6:29 a.m. Central Daylight Time. Even just after sunrise, man-made urban surfaces near downtown and streets, roads and highways were warmer than the outskirts by up to 18 degrees F (10 degrees Celsius), appearing red and orange on the image.

The images produced by ECOSTRESS are publicly available and at least one city, Las Vegas, has already used them in its efforts to combat the heat. The city painted a black asphalt street a lighter color and used the images to verify that the coating lowered the temperature of the street. These images could help inform ongoing efforts in several Texas cities to identify specific locations most affected by the heat island effect.

This tool becomes available not too soon. Researchers looked at heat exposure trends in more than 13,000 cities from 1983 to 2016 and found an almost 200% increase in overall urban heat exposure for some 1.7 billion people , about a quarter of the world’s population.

In the human body, heat can cause dehydration, which thickens the blood and makes the heart work harder, which can damage this and other organs. People with health complications such as heart disease are at higher risk. High levels of heat and humidity disrupt sweating, the body’s natural cooling system, which can lead to heat exhaustion and heatstroke.

In theory, even a healthy, well-hydrated person sitting in the shade could succumb when a measurement called wet bulb temperature, which takes into account the temperature and humidity of the air, reaches 35 degrees Celsius ( 95 degrees Fahrenheit).

“Texas is no stranger to heat, but this heat is a whole other thing,” Shreevastava says. Given this, cities in Texas must use every tool available to protect residents from its effects, including perhaps images taken from space.

Read related reports from Texas Climate News:

Houston-Galveston’s Record Nighttime Temperatures Characterize Global Warming in 2020 February 4, 2021

2020 is essentially tied with 2016 as the hottest year on record on Earth. Troubling implications for people’s health were evident in Texas and many other places. Other research has highlighted health concerns related to the climate crisis.

Those hot summer nights are getting hotter as climate change progresses June 21, 2019

“High lows” — rising nighttime minimum temperatures — are occurring in Texas, the United States and around the world. Warmer weather at night can pose significant health risks, scientists say.

As heat waves increase, green roofs could help cool Texas cities April 28, 2022

Vegetated roofs can be difficult to create and maintain, but they can be up to 40 degrees cooler than conventional roofs. They can also reduce flash flooding and provide habitat islands for pollinators.

Melissa Gaskill, an Austin-based science journalist, is the editor of Texas Climate News.

John Nielsen-Gammon is a member of the Advisory Board of Texas Climate News, serving as Regent Professor of Atmospheric Sciences at Texas A&M University. The volunteer members of the advisory board have no authority over our editorial decisions.