Medellín went green to stay cool – heat rose faster

At midday in the summer, Avenida Oriental is often congested in both directions, sidewalks packed with street vendors selling food and clothing.

Amid the heat, drivers and pedestrians seek the shade of trees that form three long rows lining the sides and centre of this avenue, one of the main streets running through downtown Medellín.

For the past 18 years, the city has promoted tree-planting, keeping people cool and receiving international acclaim.

Many cities are turning to trees for shade and other cooling benefits as the world warms, but Medellín has been an early adopter and enthusiastic leader.

Tree-planting projects began in 2008 when the city government asked the Medellín Botanical Garden to identify the most suitable species. Endemic plants from lower, drier and warmer areas were selected and a target of 880,000 trees was set.

The largest of the projects was the city’s Green Corridors, which promotes planting of species adapted to the urban environment in public spaces to mitigate rising temperatures.

The government of Colombia’s second-most populous city has since invested USD 16 million in planting trees along roads such as the Avenida Oriental which connects the San Diego neighbourhood with the city centre. Since the Green Corridors began in 2016, 18 roads and 12 waterways have been turned into green corridors.

Yet this tree planting has not reached all 4 million residents of the Medellín metropolitan area, and as global temperatures spike the city has not been immune. Experts warn that much more needs to be done to address the effects of climate change, particularly in areas where the most vulnerable people live and work.

Avenida Oriental is one of the 18 roads and 12 waterways turned into green corridors since 2016. But experts warn that much more needs to be done to address the effects of climate change (Image: Daniel Romero / VWPics / Alamy)

An insufficient effort

Gloria Morales lives with her family in the north of Medellín, in the Villa Sofía neighbourhood on the slopes of the valley that hosts Robledo, the second-most populous of  16 communes.

Narrow streets climb the slopes and university campuses sit alongside bakeries and corner shops in largely working-class neighbourhoods. People throng the busy streets. Grey concrete dominates. There are hardly any green spaces or trees to shade out the midday sun.

Much of Robledo grew during the second half of the last century without urban planning, including via illegal building, land invasions and construction with few – if any – building standards. The commune now has about 200,000 inhabitants.

A view of Robledo commune in the north of Medellín. The south of the city contains more trees (Image: Iván Erre Jota / Flickr, CC BY SA)

Gloria says that starting in May the heat has become increasingly oppressive inside her home, where ten people live, including her two infant grandchildren. That was one month before the official declaration of El Niño, which brings higher temperatures.

And this is despite the house being overshadowed by other buildings. “The sun doesn’t reach the house, but in the afternoons everything becomes unbearable. The babies break out in a rash because of the heat and we have to bathe them several times because they can’t stand it,” she says.

Like most families in the commune, her home does not have air conditioning. “The electricity bill would be enormous,” she says. “We simply can’t afford those costs.”

Such complaints are widespread across Medellín. This year, saw the highest temperature ever recorded for the month of May (33.8C) and then again for July (34.5C).

Trees can keep things cooler but Robledo, where Gloria lives, has not benefitted much from the city’s greening. The city government’s SAU platform confirms that trees are concentrated in the south. They are less common on the northern hillsides and in some areas of the city centre. The Villa Sofía neighbourhood certainly has no green corridors.

No shade, no justice

Alejandro Álvarez Vanegas, who works on sustainable development at EAFIT University in Medellín, tells Dialogue Earth that there is major inequality in how vegetation is distributed.

“There is a huge difference between the southern part, where socioeconomic levels are higher and there is a lot of greenery, and… the northern part of the city,” he says.

(Data source: Alvarez López and Zapata Henao, 2025; Map: Dialogue Earth)

Camilo Quintero Giraldo, former director of the Legal Clinic for Environment and Public Health which provides legal support on environmental issues, describes this as a clear “climate injustice”.

“High-income areas such as El Poblado have parks and trees, while others, such as Manrique and Villa Hermosa, have a shortage of green public space,” he says.

This injustice is even worse for street vendors, transport workers and others who spend hours outdoors exposed to high temperatures, even if shaded areas are available.

Robinsón Giraldo, a taxi driver for the past four years, prefers to start his working day at 2am to avoid the hottest hours, particularly in parts of the city centre that lack trees such as around the Basilica of La Candelaria. “It’s all concrete there, there’s no green lung, you feel suffocated. It’s very different if you go towards Laureles, because there are trees and the shade cools you down,” he says.

Avenida Poblado, in the southern neighbourhood of Medellín, has a lot of trees. Locals say that in contrast the city centre and north have a shortage of green spaces (Image: Daniel Romero / VWPics / Alamy)

Tracking the heat

Levels of heat in Medellín can cause more than just discomfort.

Severe exposure initially causes dehydration and cramps due to the loss of water and mineral salts, says Carmen Cecilia Gómez, a physician at the Cardioinfantil Foundation in Bogotá. If it continues, it can lead to exhaustion, dizziness, headaches, nausea and faintness, she adds.

Since 2021, the government of Antioquia region, which includes Medellín, has been developing a plan for climate adaptation through environmental health. Known as Paccsa, the initiative is currently collecting data and will then move to planning actions to reduce the effects of climate change and its impact on residents across Antioquia.

A key part of this work is collecting information on heat islands and other climatic variables. A key part of this work is collecting information on heat islands and other climatic variables.

The fight for green cities

Experts Dialogue Earth spoke to also warn that the pace of urban planting in Medellín has slowed in recent years. They say public transport projects, such as dedicated bus routes and light rail lines, have been prioritised.

Álvarez mentions the construction of 80th Street metro line, which involved cutting down 84 trees. (The metro project stated that it would provide compensation by planting hundreds more trees in other areas.)

Former congressman Daniel Carvalho, a civil engineer and urban planner by training, co-authored the Green Cities Law. This law, approved by Colombia’s legislature in 2025, gives mayors tools to strengthen climate change adaptation and build green, biodiverse and resilient urban centres. This can be done, for example, via financial incentives aimed at funding urban ecological infrastructure projects and support from the central government to conduct baseline assessments to determine needs.

Carvalho says that better integrating nature into urban planning is one of the main actions the country can take in response to climate change. Medellín, he adds, is surrounded by rich biodiversity, with thousands of species of plants, insects, birds and other animals.

An Andean cock-of-the-rock in Jardin, Antioquia region. Medellín is surrounded by rich biodiversity (Image: Addictive Stock / Alamy)

Quintero, Carvalho and Álvarez hope the law can drive tree-planting projects linked to biodiversity conservation and designed to benefit the entire population. They say the law should be leveraged to deliver a comprehensive effort that emphasises tree planting but also broadens heat response to include other actions.

“We have a long way to go. We need to work on environmental education for citizens, on involving the private sector in green projects, and on replacing hard surfaces with green surfaces,” says Carvalho.

Maps and testimonies show Medellín has become greener, but not at the pace or with the distribution required by rising temperatures.

“Medellín must face the future head-on. If we continue to deny the importance of natural spaces for citizens’ physical and mental health – and for competitiveness – we are doomed to keep experiencing disasters in a country that prides itself on being one of the most biodiverse in the world,” concludes Carvalho.