Green Corridors Program Restores Hope, Pride
By 2015, as a result of 50 years of rapid urban development, policies that led to huge growth in trips by private car and the removal of trees for traffic projects, Medellín was experiencing a severe urban heat island effect. Air pollution also reached historical highs and public pressure to address the problem was mounting.
The city implemented a three-year ‘greener Medellín for you’ program, significantly shifting its urban design paradigm. The program emphasizes equitable access, ensuring that the green corridors are developed in poorer sections of the city and that local residents play a key role in their upkeep.
The strategy targets areas with high pollution levels, such as main roads, resulting in more immediate impacts. As part of the $16.3 million initiative, 2,600 workers were employed through the project.
They initially planted 12,500 trees and palms in the 30+ corridors that cover 65 hectares. In one of the city’s busier thoroughfares, around 600 palms and trees were planted, as well as more than 90,000 smaller plants. The project also integrated 80km of new bike paths, which have been very popular.
- The corridors link various green infrastructures like squares, parks, and green curbs;
- These corridors are designed to resemble forest-like ecosystems, with over 72 native plant species chosen for their ability to remove pollutants, provide shade, and offer fruits; and
- Major concrete structures like metro stations and bridges are being fitted with green roofs and vertical gardens to reduce heat absorption.
These Green Corridors provide Medellín with a host of benefits: they help to reduce average city temperatures by 2°C and achieve a 10°C drop in some places; they capture particulate matter to improve air quality, delivering a drop in associated premature deaths and reducing rates of acute respiratory infections from 160 per thousand inhabitants to 95; and they increase urban biodiversity thanks to creation of more wildlife-friendly habitats, with birds, butterflies and other species returning to the city. The project included trees that are known to be especially effective at absorbing air pollution, such as the mango tree (Mangifera indica).
The Green Corridors project won the 2019 Ashden Award for Cooling by Nature
Medellín is now implementing a 2024-2027 Urban Plan, which emphasizes the expansion of green space and restoration of the city’s streams and rivers. At a time of rising concern about heatwaves linked to climate change, especially in cities, where the urban heat island affect can increase temperatures even more, Medellín’s approach to green corridors offers a low-cost, popular solution which other cities are increasingly looking to replicate.
Medellín’s advice for other cities
Target busiest areas for greatest impact: Oriental Avenue, one of the city’s most polluted streets with more than a million people passing through daily, was targeted as one of the key Green Corridors. The more polluted the area, the greater the potential environmental returns, meaning that including these avenues in the green, interconnected, biodiverse network will reap great rewards for general city life.
Make the most of national and local legislation opportunities: Colombian legislation stipulates that a part of cities’ budgets – Participatory Budget – is invested in projects which residents help to select through a democratic vote. The Green Corridors received a popular mandate though this vote, enabling them to be implemented across the city.
Three years after the program’s beginning, Medellín’s urban heat island effect has been reduced by 2°C. In spite of climate change, city officials expect a further decrease of 4-5°C in 28 years’ time when trees have matured. This reverses the previous trend that saw the city’s average temperatures in 2010 a whole 6°C above what should have been Medellín’s average temperature.
It’s worked so well that other cities, like Bogotá and São Paulo, are now following suit.
Residents now see birds, lizards, frogs, and bats in the corridor, some of which had not been seen in the city for years. Locals believe this has also helped to keep rats and other pests under control.
Greener Cities is a division of Crossbow Communications. Greener Cities is a resource for sustainable and resilient cities and communities around the world.
