Urban Nature-Based Solutions for Cooling and Water Quality
Summary
Medellín’s Green Corridors (“Corredores Verdes”) project integrates urban greenery to combat heat, improve water quality, and enhance resilience to climate change in urban neighborhoods.
Medellín has experienced rapid urban development over the past five decades, leading to a severe urban heat island effect, poor air quality, and water contamination. The city's dense infrastructure and lack of green space prevent effective natural cooling and reduce water absorption, worsening stormwater runoff and increasing the risk of flash floods. To address these issues, Medellín needed a solution that could mitigate high temperatures, manage stormwater, and improve air and water quality in a cost-effective, sustainable way.
Intervention
The Green Corridors initiative, launched in 2016, is part of Medellín’s "A Greener Medellín for You" program, which integrates nature-based solutions to improve urban resilience. The project creates a network of 30 "Green Corridors" across the city, transforming major roads, waterways, and public spaces into lush green areas. These corridors consist of thousands of trees, palms, and native plants that absorb rainwater, cool the air, and reduce pollution, helping to manage both water and air quality.
The Green Corridors initiative is managed by Medellín’s Department of the Environment, with significant community involvement and partnership with the Joaquin Antonio Uribe Botanical Garden. The local government prioritized this initiative to meet climate resilience goals, while citizens actively participate in budget allocation and provide feedback on green space expansion.
Each corridor is designed to incorporate diverse vegetation, including 8,800 trees and palms and more than 90,000 smaller plants across 65 hectares. These plants absorb stormwater and filter out pollutants, reducing runoff and improving water quality in nearby rivers. Green infrastructure, such as permeable surfaces and bioretention areas, helps capture rainwater, slowing down stormwater flow and enhancing groundwater recharge.
Medellín’s Department of the Environment led the project with support from local institutions, including the Joaquin Antonio Uribe Botanical Garden, which trained 75 local citizens from disadvantaged backgrounds as gardeners and planting technicians. These technicians help maintain the Green Corridors, creating jobs and building local capacity for sustainable urban management.
The project was funded through municipal investment, participatory budget allocations, and contributions from national and international environmental grants, totaling approximately $16.3M. The cost of establishing and maintaining the corridors is partially offset by reduced heat-related energy demands and improved water quality, which reduces the strain on municipal water treatment systems. The project has gained strong public backing.
Challenges
Despite its benefits, the green infrastructure requires regular upkeep to remain effective, particularly given Medellin’s tropical climate, which can impact plant survival. Additionally, scaling up green corridors across additional urban areas would require substantial investment, beyond initial budgets. Finally, sustained community engagement and education are necessary to maximize benefits and ensure long-term maintenance and support.
Outcomes
Since 2016, the project has completed 30 corridors covering 65 hectares, and monitoring shows significant positive impacts on air quality, urban cooling, and stormwater absorption. Approximately 160,787 kg of CO₂ is sequestered annually per corridor. The city is exploring further expansion of the Green Corridors to other high-impact areas to build on these results and further improve air and water quality. The initiative has lowered city temperatures by an average of 2°C, with projections to reduce temperatures by 4-5°C over the next 28 years. Further, vegetation in the Green Corridors captures particulate matter and reduces runoff, lowering pollution levels in Medellín’s rivers and streams. Finally, the corridors have created new habitats for urban wildlife and provided employment for 75 trained gardeners from local communities.
References
Urban Nature-Based Solutions for Cooling and Water Quality
Summary
Medellín’s Green Corridors (“Corredores Verdes”) project integrates urban greenery to combat heat, improve water quality, and enhance resilience to climate change in urban neighborhoods.
Medellín has experienced rapid urban development over the past five decades, leading to a severe urban heat island effect, poor air quality, and water contamination. The city's dense infrastructure and lack of green space prevent effective natural cooling and reduce water absorption, worsening stormwater runoff and increasing the risk of flash floods. To address these issues, Medellín needed a solution that could mitigate high temperatures, manage stormwater, and improve air and water quality in a cost-effective, sustainable way.
Issue
Intervention
The Green Corridors initiative, launched in 2016, is part of Medellín’s "A Greener Medellín for You" program, which integrates nature-based solutions to improve urban resilience. The project creates a network of 30 "Green Corridors" across the city, transforming major roads, waterways, and public spaces into lush green areas. These corridors consist of thousands of trees, palms, and native plants that absorb rainwater, cool the air, and reduce pollution, helping to manage both water and air quality.
The Green Corridors initiative is managed by Medellín’s Department of the Environment, with significant community involvement and partnership with the Joaquin Antonio Uribe Botanical Garden. The local government prioritized this initiative to meet climate resilience goals, while citizens actively participate in budget allocation and provide feedback on green space expansion.
Each corridor is designed to incorporate diverse vegetation, including 8,800 trees and palms and more than 90,000 smaller plants across 65 hectares. These plants absorb stormwater and filter out pollutants, reducing runoff and improving water quality in nearby rivers. Green infrastructure, such as permeable surfaces and bioretention areas, helps capture rainwater, slowing down stormwater flow and enhancing groundwater recharge.
Medellín’s Department of the Environment led the project with support from local institutions, including the Joaquin Antonio Uribe Botanical Garden, which trained 75 local citizens from disadvantaged backgrounds as gardeners and planting technicians. These technicians help maintain the Green Corridors, creating jobs and building local capacity for sustainable urban management.
The project was funded through municipal investment, participatory budget allocations, and contributions from national and international environmental grants, totaling approximately $16.3M. The cost of establishing and maintaining the corridors is partially offset by reduced heat-related energy demands and improved water quality, which reduces the strain on municipal water treatment systems. The project has gained strong public backing.
Challenges
Despite its benefits, the green infrastructure requires regular upkeep to remain effective, particularly given Medellin’s tropical climate, which can impact plant survival. Additionally, scaling up green corridors across additional urban areas would require substantial investment, beyond initial budgets. Finally, sustained community engagement and education are necessary to maximize benefits and ensure long-term maintenance and support.
Outcomes
Since 2016, the project has completed 30 corridors covering 65 hectares, and monitoring shows significant positive impacts on air quality, urban cooling, and stormwater absorption. Approximately 160,787 kg of CO₂ is sequestered annually per corridor. The city is exploring further expansion of the Green Corridors to other high-impact areas to build on these results and further improve air and water quality. The initiative has lowered city temperatures by an average of 2°C, with projections to reduce temperatures by 4-5°C over the next 28 years. Further, vegetation in the Green Corridors captures particulate matter and reduces runoff, lowering pollution levels in Medellín’s rivers and streams. Finally, the corridors have created new habitats for urban wildlife and provided employment for 75 trained gardeners from local communities.
Issues |
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Climate Change and Water |
Solutions |
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Sustainable Water Supply & Climate Solutions |
References
BBC Future. How Medellín is beating the heat with green corridors. Retrieved from https://www.bbc.com/future/article/20230922-how-medellin-is-beating-the-heat-with-green-corridors
PreventionWeb. Colombia: green corridors help reduce heat risk in Medellín. Retrieved from https://www.preventionweb.net/news/colombia-green-corridors-help-reduce-heat-risk-medellin
Resilience.org. Urban landscapes in the 21st century: Can eco-cities tackle climate change and pollution?. Retrieved from https://www.resilience.org/stories/2024-10-23/urban-landscapes-in-the-21st-century-can-eco-cities-tackle-climate-change-and-pollution/
World Economic Forum. Climate change: Colombia takes action to tackle rising heat. Retrieved from https://www.weforum.org/stories/2021/08/colombias-medellin-plants-green-corridors-to-beat-rising-heat
Scroll.in. Colombia: Medellín’s green corridors turned the clock back on global warming. Retrieved from https://scroll.in/article/1067528/how-a-colombian-citys-green-corridors-turned-the-clock-back-on-global-warming
EcoPortal.net. Colombian city managed to reduce the heat with green corridors. Retrieved from https://www.ecoportal.net/en/temas-especiales/habitat-urbano/reducir-calor-corredores-verdes/
NetworkNature. Alcaldía de Medellín - Green Corridors Initiative. Retrieved from https://networknature.eu/casestudy/21677
BLACKSWANS | GREENSHOOTS. Medellín’s Interconnected Green Corridors. Retrieved from https://www.blackswansgreenshoots.com/medellins-interconnected-green-corridors/
The Dirt. Urban Ecosystem Services: Medellín’s Cooling Green Corridors. Retrieved from https://thedirt.news/urban-ecosystem-services-medellins-cooling-green-corridors/