(CNN)
-- Buenos Aires recorded its highest temperature for the month in 60 years this February, amid a series of heat waves gripping Argentina.
This means that millions of people living in urban areas are desperately trying to stay cool.
The climate crisis is making extreme heat more frequent and longer lasting, but cities without well thought out design can make life even more sweltering.
Heat waves: how to protect yourself from extreme heat and what illnesses and problems it can cause
Air conditioners may keep you cool inside, but they only add to the heat outside.
And, in most cases, they contribute to the climate crisis by increasing emissions that warm the planet.
Public transportation can be unbearable on a hot day, but driving a car that runs on gasoline instead only makes traffic worse, adding heat and emissions as well.
A lack of trees means a lack of shade, and buildings made of dark materials lead to hotter interiors, which means more air conditioning.
It's a vicious circle, but there are other solutions.
Here are eight cities that are taking some of the heat out of their summers.
Medellín, Colombia: planting trees in the streets, not just in the parks
A green corridor in Medellin, Colombia.
The city received an award for its green corridors project.
When it's really hot, people with air conditioning can stay indoors, but not everyone has that luxury and, well, who wants to stay indoors all the time?
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For cities that are not on the coast, parks that offer shade are a good option.
However, Colombia's second largest city, Medellín, has created an entire shady metropolis with its award-winning Corredores Verdes project.
This network has transformed 18 boulevards and 12 waterways into lush green bike lanes and promenades that connect city parks and other popular places.
Temperatures have dropped in and around these areas by about 3°C, and officials hope that by 2030 they can drop to as much as 5°C.
"Urban forests are the best for city heat," Kathy Baughman McLeod, director of the Adrienne Arsht-Rockefeller Foundation (Arsht-Rock) Center for Resilience at the Atlantic Council, told CNN.
"Medellín has lowered the city's average summer temperature, which is remarkable."
By 2019, the city had planted more than 8,000 trees and more than 350,000 shrubs.
It also uses an area under an elevated metro line to collect rainwater coming down from the bridge, capturing it in a pipe system to help irrigate the green corridors.
Vienna: make a splash!
A boy uses a water fountain to cool off in the Schwarzenberg Square in Vienna, Austria.
As in much of Europe, many Viennese don't have air conditioning, so water is a big part of the way the Austrian capital stays cool.
For those who don't have time to take a dip in the Danube, the city offers refreshing parks with mist-spraying "trees" where people can "shower" or just sit nearby to enjoy the cooler temperatures brought to its environment.
Children, who are often more vulnerable to extreme heat than adults, often play in the city's wading pools or run in the pop-up water fountains, typically hoses with holes in them, that the city government implements on the hottest days. , even in areas like Karlsplatz, a popular square in the city.
Vienna also has a large number of water sources to drink and 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 seem like a quick and easy fix. But it's not a long-term sustainable solution because of the power source and the waste heat the unit gives off," McLeod said.
"So thinking about how to get more airflow, use water features, and get windows to open in some of the older buildings is key. Nature-based solutions are best for extreme heat."
Abu Dhabi, United Arab Emirates: using old refrigeration techniques and modernizing them
Abu Dhabi's Al Bahar Towers use a dynamic sun shading system to keep the building cool.
Parts of the Middle East are some of the hottest inhabited places on Earth.
Temperatures in Abu Dhabi can exceed 50°C.
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 Arabian cooling architectural technique has made a comeback, with a modern twist.
Get to know the Louvre Museum in Abu Dhabi
Mashrabiya
refers to the lattices often seen in Islamic architecture, sometimes surrounding a small balcony, that scatter sunlight and keep buildings cool without completely blocking light.
They are designed to favor the breeze and offer respite from the heat inside a building.
The idea is to prevent sunlight from falling directly on the outside of the building.
That's what inspired the design of the Al Bahar towers, a 25-story building draped in more than 1,000 hexagonal shutters with built-in sensors that allow them to respond to the movements of the sun.
When the sun hits the blinds, they unfold like an umbrella to keep out the heat.
Without these measures, the outside of such a building in Abu Dhabi could reach up to 90°C.
The technique has helped reduce the building's need for air conditioning by 50%.
Great, isn't it?
Miami: Resolving Heat Traps
The shady bus shelter project in Miami.
Medellín, Colombia, may have shown that urban forests, or simply planting more trees, can cool a city, but Miami's Dade County has given a lot of thought to which parts of the city need cooling the most.
Neat Streets Miami, a board convened by the county council, recognized that bus stops had become real danger zones during heat waves, so they planted trees around 10 stops.
They produced a guide on which trees work best and where to plant them so that other areas could replicate the project.
And they have.
There are now 71 green bus stops in the country, most of them carried out by communities that have asked the government for resources to green their own bus stops.
To make it more fun, the organizers also held a haiku poetry contest, selecting the top 10 to be recorded on the sidewalks of the original stops.
Here is one of them:
The trees
have also missed the bus, see how they wave
their many sad arms
- Ariel Francisco
Athens: work with what you have
Hadrian's Aqueduct was built around AD 140 and can still carry water today.
Not every city has an ancient aqueduct, but the Greek capital, Athens, does.
The Adriano aqueduct was once used as the main source of water, using a system of pipes that worked with gravity to allow water to flow from its source to the city for human consumption.
Today the water is not drinkable, but the city is studying how to recover the 800,000 cubic meters of water that are thrown into the sea each year.
One of the uses will be to irrigate new green areas along the 20 kilometers of the structure, which will help to reduce the heat of the surrounding areas.
The water will also be used to mist, like in Vienna.
Even for cities without such ancient infrastructure, Athens is a good reminder that disused water systems can revive at some point.
Los Angeles: paint the city white
Workers painting a highway in Los Angeles to cope with the heat.
This measure is a bit more controversial.
Some cities have tried painting rooftops white to reflect sunlight and keep buildings cool, but Los Angeles has gone further and is painting entire highways white.
Dark items, like asphalt, absorb sunlight and return that energy to the air as heat.
In theory, painting the asphalt white would nip that process in the bud and allow the air temperature to cool down.
These cities have the worst "heat islands," and temperatures can rise 5.5 to 11 degrees within a few blocks.
The idea works up to a point.
Researchers Ariane Middel and V. Kelly Turner found that the technique cooled the streets by about 5°C, but there was a major side effect.
The same researchers also said that the extra heat reflected off the roads was likely absorbed by… people.
This means that if you're a few blocks away, the white streets can help you feel cooler, but if you're on the painted street, you might feel hotter.
Nonetheless, Los Angeles is continuing with this program to see what works and what doesn't.
It currently uses a grayish-white substance called CoolSeal, which was once used to help hide ground-based planes from satellites, but it's possible that another type of paint might give different results.
Painting the roofs has been more successful.
Results vary depending on the level of heat and the materials the roof is made of, but in places like Ahmedabad, India, where it is very hot, cool roofs have reduced the heat of the houses.
According to the Berkeley Lab's Heat Island Group, a black roof can be up to 30°C hotter than a white roof.
Another option is the green roof.
Cities around the world have created "gardens in the sky" to cool buildings.
Paris: good organization
People cool off in the Tuileries Garden on a hot afternoon in Paris.
It is very hot in the French capital.
This summer the temperatures have exceeded 40 °C, but the combination of tall buildings, limestone monuments and paved roads with heavy traffic makes the feeling of heat even greater.
The city has a strong "urban heat island" effect, where it is often 9°C hotter in the city center on a summer's day than inland Paris.
But Paris Mayor Anne Hidalgo is credited with implementing some of the world's most innovative heat-fighting measures, and the city's heat plan is truly comprehensive.
The main result is a city full of "fresh islands".
Parisians can use an app called EXTREMA to be guided to more than 800 air-conditioned cool spots, parks, water features and museums, for example, and reach them via a naturally cooled walkway.
The idea is that a cool island is always a maximum of seven minutes on foot for everyone.
Like Vienna, Paris uses fog machines on hot days.
It also has dozens of new "splash fountains" in addition to its many traditional fountains, which are very shallow pools with fountain-like effects.
Paris' heat plan includes a registry that identifies the most vulnerable, so officials can check on them over the phone and offer advice on staying cool.
Kindergartens have temporary air conditioners in their classrooms, and parks and public pools stay open longer hours into the night.
And, like Los Angeles, Paris is trying to remove heat from its roads and sidewalks by "demineralizing" them, using more porous materials.
Now that sounds like a plan.
The north suffers from unprecedented heat.
Will the same thing happen in the southern summer?
Seville, Spain: Name your heat waves
Visitors use a public fountain in Seville, Spain.
The world has been naming hurricanes, cyclones and typhoons for decades for a reason: A named storm makes you pay attention.
The city of Seville, in southern Spain, is taking that approach with heat waves, becoming the first in the world to do so.
The heat wave last July was called Zoe.
"Naming heat waves is a positive thing because it means we're acknowledging how deadly they are, and they're here to stay. It's not a casual heat wave," said Arsht-Rock's McLeod.
"This is something we're going to live with for a long time, regardless of what we do with our emissions."
But what Seville is doing is much more than just naming.
Arsht-Rock is working with Seville on a new heat wave categorization system based on expected negative health outcomes.
The idea is to avoid scientific jargon that most people don't understand and tie alert levels to what a heat wave can do.
A 2018 Brown University study of 20 heat alert systems in the United States found that only Philadelphia's heat alert system was effective in saving lives, in part because it uses health-based metrics.
"Other than physical interventions for heat, naming and categorizing heat waves is the best and most immediate thing to do," McLeod said.
"Because that's the key: the heat is killing people, and that's because people aren't aware of the magnitude of the problem."
Editor's Note:
This article was originally published in August 2022.
Taylor Ward, Schams Elwazer, and Vanessa Ko contributed reporting.
