Nature-based solutions

Actions based on the protection, conservation, restoration, sustainable use and management of natural or modified terrestrial, freshwater, coastal and marine ecosystems. These actions address social, economic, governance and environmental challenges effectively and adaptively, while simultaneously, ecosystem services, disaster risk reduction, resilience and biodiversity benefits and supporting human well-being.


1. Nature-based solutions (NbS) use Green and Blue infrastructure.

2. See also "Green infrastructure" and "Blue infrastructure".

3. Sometimes also referred to as "Environment-based solutions".


Modified from UNEP, 2022



Green corridors of Colombia

The country of Colombia in South America has the second highest level of biodiversity in the world. Medellín, the second largest city in Colombia after its capital city Bogotá, is located in the central region of the Andes mountains. In 2018, its population was 2.5 million. Medellin faces the threat of rising urban temperatures, driven by climate change and accelerated by the urban heat island effect. To protect its citizens and workers, the city has turned to sustainable cooling solutions. The city authorities have spent the past few years transforming the verges of 18 roads and 12 waterways into an award-winning green metropolis of shade. Planting vegetation along busy streets and former waterways creates a better environment for the city residents by purifying the air and reducing temperatures of built-up areas, in addition to shading bike lanes and pathways. The 1.5 million m2 of public space is enjoyed by all members of society.

By 2019, the city had planted 8,000 trees and 350,000 shrubs, focusing on areas that did not have green spaces. The carefully selected trees, palms, and various smaller plants have allowed the native wildlife to return. The area beneath raised metro lines is used to collect surface runoff from the bridge to water the green belts. The web-like network connects the city’s parks and waterways with lush green cycling lanes and walkways. Temperatures in these intervention areas and surroundings have dropped by over 3oC, from 31.6oC to 27.1oC. Surface temperatures dropped from 40.5oC to 30.2oC. The city’s average summer temperature has also dropped. The particulate pollutant PM 2.5 levels fell from 21.81 μg/m3 to 20.26 μg/m3; PM 10 levels fell from 46.04 μg/m3 to 40.4 μg/m3 and ozone levels dropped from 30.1 μg/m3 to 26.32 μg/m3. The construction of dedicated bike paths resulted in a 34.6 percent increase in cycling activity cycling, and walking rose by 4 percent. Overall, these had significant health benefits for the city’s residents. This was quantified in the dropping of the city’s morbidity rate from acute respiratory infections from 159.8 per thousand inhabitants to 95.3 per thousand inhabitants. The project also created employment and training opportunities for disadvantaged communities by creating thousands of positions for gardeners and workers.