The Colombian metropolis has transformed streets and rivers into green corridors, reducing temperatures in places and improving the quality of life

Medellín, Colombia’s second largest city, once infamous for its history of drug trafficking and the criminal figure of Pablo Escobar, is now undergoing an unprecedented ecological transformation. Since 2016, thanks to the “Corredores Verdes” project, the city has embarked on an ambitious path to combat the urban heat island effect, improve air quality, and offer more livable public spaces to its 2,5 million inhabitants.

The project created 30 green corridors spanning 20 kilometers, transforming previously concrete-dominated urban areas into green spaces. More than 880.000 trees and 2,5 million softwoods were planted, covering 70 hectares.
The results were astonishing: in just three years, the average air temperature in the affected areas dropped from 31,6 degrees Celsius to 27,1, while the surface temperature decreased by more than 10 degrees Celsius, from 40,5°C to 30,2°C.

Tangible environmental and social benefits from particulate matter to ozone

In addition to the reduction in temperatures, green corridors have led to significant improvements in air quality. Between 2016 and 2019, levels of fine particulate matter PM2.5 decreased from 21,81 µg/m³ to 20,26 µg/m³, while PM10 decreased from 46,04 µg/m³ to 40,4 µg/m³. Not only that, ozone also decreased from 30,1 µg/m³ to 26,32 µg/m³.
These improvements have had a direct impact on public health: the morbidity rate for acute respiratory infections has decreased from 159,8 to 95,3 cases per thousand inhabitants.

The project also promoted sustainable mobility, with a 34,6 percent increase in cycling and a 4 percent increase in walking, thanks to the creation of 80 km of new cycle paths.
From a social perspective, 107 citizens from disadvantaged communities were trained as urban gardeners, providing them with job opportunities and contributing to the maintenance of green corridors.

Replicable model in Bogotá and Barranquilla and globally

The success of Medellín’s green corridors has attracted international attention, becoming an example of how nature-based solutions can address contemporary urban challenges. In 2019, the project received the Ashden Award in the “Cooling by Nature” category.
Other cities, such as Bogotá, Barranquilla and Cali in Colombia, and São Paulo in Brazil, have begun to implement similar projects, inspired by the experience of Medellín, while Milan (with the “Forestami” project) and Singapore have adopted parallel strategies.
The project has also prompted further local initiatives, such as the proposal to transform the city's central airport into a large urban park, although this idea is currently under discussion.

Now you pedal and walk, but at the beginning it wasn't easy

With all these new green spaces, citizens have started to move around on foot or by bike again. Bike lanes have increased, and some have left their cars in the garage for the first time in their lives.

“I used to always take the bus, now I go to work by bike. It's good for me and the environment,”

says Juan, an employee who walks along the tree-lined avenue of Carrera 52 every morning.
Of course, it has not been a smooth ride. At first, some traders were skeptical:

“If you put trees in front of my store, where will customers park?”

Then, over time, they realized that a shaded sidewalk attracts more passers-by, and therefore more business. And then there is the challenge of maintaining all this greenery: the trees must be cared for, watered, pruned. But the citizens, many of whom have found work in the maintenance of the “Corredores Verdes,” now take care of them with pride.

The Convinced Vision of Sérgio Orozco and Carlos Cadena Gaitán

Sérgio Orozco, Secretary of Environment of Medellín from 2016 to 2019, stated:

“The drop in temperature, in some areas more than 3 degrees Celsius, was greater than we expected. We also saw the return of animals that had not been seen in the city for years.”

Carlos Cadena-Gaitan, sustainability expert and professor at the EAFIT University of Medellín, stressed the importance of these initiatives:

“Green corridors demonstrate how metropolises can reinvent themselves through sustainable solutions, improving the quality of life of citizens and addressing climate challenges.”

At the center of social inclusion, public health and sustainable mobility

The experience of Medellín shows that it is possible to transform cities into more livable and resilient places through targeted and sustainable interventions. Green corridors have not only mitigated the effects of climate change, but have also promoted social inclusion, public health and sustainable mobility.
In an era where environmental and social challenges are increasingly interconnected, the Colombian metropolis offers a replicable model for other cities around the world, showing that with vision, commitment and collaboration, it is possible to build a greener and more sustainable future for all. And it doesn't end there...

A summary of the project “Corredores Verdes” launched by the city of Medellín in Colombia

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