Medellín’s Green Urban Spine

Medellín’s Green Corridors is a flagship nature-based urban cooling program launched in 2016 to tackle extreme heat, pollution, and the scarcity of public green space. By creating 30 interconnected green corridors across the city -transforming roadsides, waterways, and under-viaduct spaces- the initiative has delivered a measurable 2°C reduction in urban temperatures, planted over 8,800 trees and 90,000 smaller plants, restored 65 hectares of green area, and trained and employed 75 people from vulnerable communities as gardening technicians. The program demonstrates how large-scale NbS can reduce heat stress, strengthen biodiversity, improve air quality, and unlock new livelihood opportunities.

Medellín’s implementation approach combined rigorous planning, ecological design, and social inclusion.

1. Baseline assessment & corridor selection
   • Identified heat-stressed mobility corridors and underutilized spaces (e.g., under viaducts, medians, riverbanks).
   • Mapped connectivity opportunities to link parks, river edges, hills, and green pockets.
2. Designing ecological corridors
   • Multi-layered planting strategy: low, medium, and tall vegetation to mimic forest structure.
   • Use of native and tropical species adapted to local climate.
   • Integrated continuous shade, permeability, and microhabitat creation.
3. Capacity building & green workforce creation
   • Trained 75 local residents from vulnerable communities as planting technicians and maintenance stewards.
   • Built new municipal capacity for long-term ecological care.
4. Construction & installation (2016–2019)
   • Tree and plant installation along roads, waterways, and major transport routes.
   • Conversion of concrete medians, vertical walls, and hard public spaces into green infrastructure.
   • Integration with mobility improvements (cycling routes, pedestrian pathways).
5. Maintenance & ecological monitoring
   • Daily and weekly care by municipal gardening teams.
   • Continuous assessment of plant health, cooling impacts, and biodiversity indicators.
6. Scaling & replication
   • By 2019, 30 full corridors delivered; further corridors planned under “Medellín Verde” strategy.

Delivering the Green Corridors required strong institutional coordination and technical collaboration.

• Municipality of Medellín (Secretaría de Medio Ambiente) - project lead.
• Urban planning, mobility, and public works departments - integration with streets and transport.
• Botanical Garden of Medellín - species selection and ecological design.
• Community organizations - recruitment, training, and stewardship.

Public communication supported citizen ownership and long-term care.

• Awareness raising on the benefits of urban trees and cooling.
• Signage and visual campaigns explaining the ecological function of corridors.
• School and neighborhood engagement for corridor care.
• Promotion through city branding (Medellín Verde / Corredores Verdes “Green Corridors”).

A single, coordinated investment underpinned the program.

• US$16.3 million total investment in design, planting, training, and maintenance. 
• Municipal budget + co-financing through environmental programs.
• Training components supported through social inclusion and employment missions.

The project delivered measurable environmental, social, and climate benefits.

• 2°C temperature reduction improving comfort for residents and workers.
• Improved air quality via particulate matter capture.
• Reduced heat-related health risks, especially for vulnerable groups.
• Enhanced biodiversity, creating new habitats across the valley.
• Economic co-benefits through job creation, increased tourism attractiveness, and lower cooling costs.
• Stronger climate resilience, combining mitigation and adaptation in a single intervention.

Medellín overcame several challenges typical of large-scale NbS.

• Balancing maintenance needs with budget constraints.
• Ensuring plant survival in heavily paved areas.
• Managing construction impacts in high-traffic corridors.
• Sustaining cross-departmental coordination.
• Addressing community skepticism during early phases (e.g., fear of reduced street visibility or security).

Medellín’s Green Corridors demonstrate a replicable model for dense cities seeking rapid, nature-based cooling. The program shows that sustained political will, integrated corridor design, employment pathways, and long-term maintenance systems are essential. Cities with limited space can still deliver significant climate adaptation outcomes by transforming transport corridors, medians, and underused urban land. The approach is highly transferable to cities in similar climatic and topographic conditions, especially those suffering from air pollution, heat stress, and fragmented green infrastructure.

For global application, key takeaways include:

• Combine cooling, biodiversity, and livelihoods for high-impact urban resilience.
• Prioritize connectivity, corridors multiply the effect of isolated parks.
• Invest in local ecological expertise and community stewardship.
• Use measurable indicators (temperature, plant survival, PM reduction) to drive expansion.

Ultimately, Medellín shows that when cities treat nature as core infrastructure, they can cool faster, adapt smarter, and build resilience that truly benefits all residents.