Here’s how eight cities are taking some of the heat out of their summers.
Medellín, Colombia: Grow trees on the streets, not just in parks
When it’s really hot, people with air conditioning can stay indoors, but not everyone has that luxury and — well, who wants to keep saying that? For non-coastal cities, parks that offer shade are a good option. Colombia’s second largest city, Medellín, however, has created an entire shadow metropolis with its award-winning Green Corridors project. The web-like network has transformed 18 streets and 12 waterways into green bike and pedestrian paths connecting the city’s parks and other frequently visited locations. Temperatures have dropped in and around these areas by as much as 5.5 degrees Fahrenheit (about 3 degrees Celsius), and officials hope that before 2030, it could drop as much as 9 degrees Fahrenheit (5 degrees Celsius). “Urban forests are the best thing about the heat of cities,” Kathy Bowman McLeod, director of the Adrienne Arsht-Rock Foundation’s Resilience Center at the Atlantic Council, told CNN. “Medellín has dropped the city’s average summer temperature, which is remarkable.” By 2019, the city had planted more than 8,000 trees and over 350,000 shrubs. It also uses an area under an elevated subway line to collect rainwater that flows under the bridge, collecting it in a system of pipes that help irrigate green zones.
Vienna: Splish, splash, splosh
Like much of Europe, many in Vienna don’t have air conditioning, so water is a big part of how the Austrian capital keeps its cool. For those who don’t have time for a dip in the Danube, the city offers cooling parks with mist-spraying “trees” where people can either “shower” or simply sit nearby to enjoy the cooler temperatures their surroundings bring . Children, who are generally more vulnerable to extreme heat than adults, are often seen playing in city pools or running in pop-up water spots — usually tires with holes — that the city government puts up at the hottest pools. days, including areas such as Karlsplatz, a popular city square. Vienna also has a huge number of drinking fountains to keep people hydrated – more than 1,100 for its population of 1.9 million – which is important for preventing heat-related illnesses. “Air conditioning in homes may sound like a quick and easy fix. But it’s not a long-term sustainable solution because of the energy source and the waste heat coming out of the unit,” McLeod said. “So thinking about how to get more airflow, use water features and open windows in some of the older buildings is key. Nature-based solutions are the best for extreme heat.”
Abu Dhabi, United Arab Emirates: Use old refrigeration techniques and modernize them
Parts of the Middle East are some of the hottest inhabited places on Earth. Temperatures in Abu Dhabi can soar to over 120 degrees Fahrenheit (over 50 Celsius). Air conditioning is considered a necessity and people tend to spend a lot of time indoors.
But people here haven’t always had air conditioning, and an ancient Arabic cooling architecture has come back – with a modern twist.
Mashrabiya refers to the mesh screens often seen in Islamic architecture, sometimes around a small balcony, that diffuse sunlight and keep buildings cool without blocking the light completely. They are designed to encourage breezes and provide a respite from the heat within a building. The idea is to essentially stop direct sunlight from landing on the exterior of a building.
This inspired the design of the Al Bahar Towers, a 25-story building wrapped in more than 1,000 hexagonal shades with built-in sensors that allow them to respond to the sun’s movements. When the sun hits the shades, they unfold like an umbrella to ward off the heat. Without these measures, the outside of such a building in Abu Dhabi could reach 200 degrees (about 90 Celsius).
The technique helped reduce the building’s need for air conditioning by 50%. Nice huh;
Miami: Target heat traps
In many cities, catching the bus can mean a long wait. If it’s very hot, the wait can be even more punishing – unless, of course, that bus stop has been carefully designed to include natural shade. Medellin, Colombia may have proven that urban forests, or simply planting more trees, can cool a city, but Miami’s Dade County has thought hard about which parts of the city need cooling the most. Neat Streets Miami, a council convened by the county council, recognized that bus stops had turned into real danger zones during the heat waves, so they planted trees at about 10 stops. They wrote a guide on which trees work best and where to plant them so other areas can replicate the project. And what they have. There are now 71 green bus stops in the country, most from communities that applied to the government for funding to green their own bus stops. To make it more fun, the organizers also organized a haiku poetry competition and selected the best 10 to carve on the sidewalks from the starting stops. Trees have too they missed their bus — look how they’re waving their many sad hands — Ariel Francis
Athens: Work with what you have
Not every city has an ancient aqueduct at its disposal, but the Greek capital of Athens does. Hadrian’s aqueduct was once used as the main source of water, using a system of gravity-operated pipes to allow water to flow from its source into the city for human consumption. The water today is not potable, but the city is looking for ways to save the 800,000 cubic meters of water that flows as waste into the sea every year. One use will be to irrigate new green belts that will run the length of the 20km structure, which will help remove heat from the areas around it. Water will also be used for fogging, as in Vienna. Even for cities without such old infrastructure, Athens is a good reminder that dormant water systems can sometimes be revived.
Los Angeles: Paint the city white
This one is a bit more controversial. Some cities have experimented with painting rooftops white to reflect sunlight and keep buildings cool, but Los Angeles has gone one step further and is painting entire streets white. Dark things like asphalt absorb sunlight and emit that energy back into the air as heat. Painting the asphalt white would theoretically nip this process in the bud and lead to cooler air temperatures. The idea has some merit. Researchers Ariane Middel and V. Kelly Turner found that the technique made the streets themselves about 10 degrees cooler. But there was a significant impact. The same researchers also said it’s possible that the extra heat reflected off the roads is being absorbed by … people. This means that if you’re a few blocks away, the white streets might help you feel cooler, but if you’re on the street, you could actually feel warmer. However, LA is continuing with this program to see what works and what doesn’t. It currently uses a gray-white substance called CoolSeal, once used to hide grounded aircraft from satellites, but it’s possible that another type of paint could yield different results. Roof painting was more successful. Results vary depending on the heat level and the materials a roof is made of, but in places like Ahmedabad in India, where it gets very hot, cool roofs have shaved 3-8 degrees Fahrenheit off the heat in homes. According to Berkeley Lab’s Heat Island team, a black roof on the left could be as much as 54 degrees (about 30 Celsius) warmer than a white roof. Another option is the green roof. Cities around the world have created ‘sky gardens’ to cool buildings.
Paris: Get really organized
The French capital is seriously heating up. Temperatures there have topped 104 degrees Fahrenheit (40 Celsius) this summer, but the combination of high-rise buildings, limestone monuments and busy cobbled streets means it can feel even hotter. The city has a strong urban heat island effect, where it is often 18 degrees warmer in the city center on a summer’s day than inland Paris. However, Paris mayor Anne Hidalgo has been credited with implementing some of the world’s most innovative measures to combat the heat, and the city’s heat plan is truly comprehensive. The main result is a city full of “cool islands”. Parisians can use an app called EXTREMA to guide them to more than 800 cool spots — parks, fountains and air-conditioned museums, for example — and get there via a naturally cooled walkway. The idea is that a cool island is always at most a seven minute walk for everyone. Like Vienna, Paris uses fog machines on hot days. It also has dozens of new “fountains”, in addition to its many traditional fountains, which are very shallow pools with a fountain-like effect. The Paris heat plan includes a register that identifies the most vulnerable so officials can check on them by phone and offer advice on staying cool. Kindergartens have temporary air conditioners in their classrooms, and public parks and swimming pools stay open longer into the night. And like Los Angeles, Paris is trying to remove heat from its streets and sidewalks by “demineralizing” them, using more porous materials. Now that sounds like a plan.
Seville, Spain: Name your heat waves
People have been naming hurricanes, cyclones and hurricanes for decades for one reason: A named storm makes you sit up and take notice. The southern Spanish city of Seville is taking this heat wave approach, becoming the first in the world to do so. The July heat wave there was called Life. “The naming of heat waves is positive because it means we recognize how deadly they are and that they are here to stay. This is not a random heat wave,” said Arsht-Rock’s McLeod. “This is something we will live for…
