Medellín

Medellín, Colombia’s second-largest city, faces significant challenges as it navigates the impacts of climate change and socio-economic disparities. Rising global temperatures have intensified the urban heat island effect, where vast stretches of concrete and asphalt absorb and retain heat, pushing city temperatures to uncomfortable and even dangerous levels. Heat waves exacerbate this issue, posing a serious threat to public health and well-being.

Compounding the environmental crisis was a social one: Medellín had become home to many displaced individuals, victims of armed conflict, and people from impoverished rural areas seeking refuge in the city. For these communities, finding stable employment and building a future had remained a daunting challenge, further widening socio-economic inequalities. The lack of job opportunities in Medellín had affected not only the vulnerable but also the broader workforce, creating a cycle of poverty and limited prospects. Addressing these intersecting challenges required innovative solutions that could simultaneously combat climate change and provide livelihoods.

In this context, Medellín’s Green Corridors program emerged as a beacon of hope, offering a holistic approach to urban transformation. By tackling rising temperatures and creating job opportunities, it addressed the city’s environmental and social challenges, paving the way for a more resilient and inclusive future.

As global temperatures rise, cities face mounting challenges from the urban heat island effect, where expansive concrete and asphalt surfaces trap and amplify heat. To combat these effects and adapt to climate change, Medellín has launched the Green Corridors program, a transformative urban greening initiative aimed at improving environmental conditions, boosting biodiversity, and enhancing residents’ quality of life.

The project has established 30 lush corridors—18 along major roads and 12 adjacent to waterways—covering 65 hectares of naturalized spaces in waterways and 6.2 hectares along roads. Additionally, 2 hectares of previously paved surfaces have been converted into green areas. These corridors reduce heat through shading, minimize the heat radiated by hard surfaces, and promote cooling via plant transpiration.

The program has involved the planting of 8,300 trees and palms and over 353,000 shrubs, with species selected by the Botanical Garden of Medellín to support wildlife and enhance ecological connectivity. Each corridor mimics natural forest ecosystems with low, medium, and tall vegetation to attract birds, insects, and mammals. Highlights include the revitalized Oriental Avenue and La Hueso Green Corridor, which features innovative rainwater collection systems to irrigate green walls and gardens. By integrating nature into its urban landscape, Medellín demonstrates a scalable model for sustainable urban development

Medellín’s «Green Corridors» project exemplifies how cities can tackle the dual crises of climate change and social inequality through visionary urban greening initiatives. Launched in 2016, this ambitious program was designed to address rising urban temperatures, air pollution, and ecological degradation in a city uniquely challenged by dense urbanization, mountainous terrain, and heavy vehicle emissions.

The project has transformed Medellín’s landscape with over 30 green corridors spanning roadways, parks, and waterways. Early efforts introduced 120,000 plants and 12,500 trees, scaling up to an astonishing 2.5 million plants and 880,000 trees by 2021.

These efforts have significantly reduced the city’s urban heat island effect, achieving temperature drops of 2°C within three years and aiming for a further 4-5°C reduction over the next decades. Simultaneously, the green spaces are absorbing CO2, improving air quality, and enhancing biodiversity, creating a more resilient ecosystem.

The initiative’s impact extends beyond environmental benefits. Recognizing Medellín’s high unemployment rates, especially among displaced individuals and victims of conflict, the program incorporated a robust social component. Seventy-five individuals from vulnerable backgrounds were trained as gardeners and technicians, gaining meaningful employment and a sense of purpose. Their work not only supports their families but also fosters community engagement in maintaining these green spaces.

Public health outcomes have also improved, with reduced respiratory illnesses attributed to better air quality.

These corridors, combined with innovative features like rainwater harvesting and vertical gardens, have redefined Medellín’s urban fabric, proving that sustainable infrastructure can address both ecological and social needs.

With a modest investment of $16.3 million, Medellín has crafted a replicable model for urban centres worldwide, showing that addressing climate change and inequality need not be mutually exclusive. Instead, cities can create greener, healthier, and more inclusive environments, inspiring a sustainable future.