Cities represent the most urgent challenge in combating global warming. Their population continues to grow (55% of the world’s population currently resides in urban areas, and according to the United Nations, it will reach 70% by 2050) and they are the primary source of greenhouse gas emissions.
Extreme weather events (heatwaves, droughts, heavy rainfall, and floods) have also multiplied in recent years. According to a study on climate change and cities published in 2019 by the Swiss Federal Institute of Technology-ETH Zurich, after evaluating over 500 cities worldwide, Madrid could have a climate similar to the dry Marrakech and the foggy London, and Barcelona could become Mediterranean in less than 30 years.
Given these predictions, it is time to take action. In this report, we highlight some examples implemented in different cities around the world.
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Heat islands: the urban hell
This scientific prediction is not at all far-fetched. Cities have been experiencing the so-called urban heat island effect for some time now: temperatures in the city center can be up to 10 degrees Celsius higher than in the surrounding areas due to the concentration of buildings, cars, machinery, and materials such as concrete and asphalt, which release the heat accumulated during the day at night.
The problem of extreme heat in urban areas is not insignificant. Experts believe that this phenomenon will become increasingly frequent and intense. According to the C40 Cities Leadership Group,a network of mayors from around a hundred major cities worldwide collaborating to take urgent action against the climate crisis (founded in 2005 by the former Mayor of London, Ken Livingstone), the urban population on the planet will reach 3.5 billion people by the middle of this century, and nearly half, 1.6 billion, “will live under these conditions of sustained heat.”
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Urban shelters and thermal oases
The construction of urban climate shelters is one of these initiatives in response to heat islands. Barcelona is a pioneer in Spain in creating these areas to protect against high temperatures. The city has a network of 200 spaces conditioned to 26 degrees Celsius, with resting areas and provided with shade and water. The goal is for any citizen to have access to one of these spaces within a 10-minute walk from their home. Bilbao also has 130 shelters, 66 of which are outdoors. In Málaga, they have given the green light to the creation of these types of spaces, and Zaragoza plans to create the Climate Oasis Network, with 29 zones. The idea of climate shelters originated in Paris in 2017 when they proposed transforming the courtyards of schools and high schools – there are around 800 in the city – into cool oases or islands.
Techniques from 3,000 years ago to cool down Seville
The urban design project Cartuja Qanat, promoted by the City Council of Seville, the Scientific and Technological Park PCT Cartuja, the University of Seville and the municipal water company Emasesa, with an investment of five million euros, is another clear example of an innovative response to the phenomenon of heat islands.
Cartuja Qanat – qanat means canal in Arabic – was inaugurated at the end of 2022 in Seville, on the Island of La Cartuja, the site of Expo 92. It updates bioclimatic techniques that the Persians used 3,000 years ago to create a more livable public space (consisting of an amphitheater, a bazaar, and a tempered island) where the temperature can be sustainably lowered, generating a microclimate for the 30,000 people who work and study there daily.
“This experience improves environmental comfort and promotes social interaction and sustainable models of urban growth. The intention is to replicate it in other urban spaces,” says Luis Pérez, General Director of PCT Cartuja.
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From gray to green: Reconciliation with nature
The proposal in Seville shows that cement, as a symbol of urbanisation, must give way to a new city model that no longer turns its back on nature but reconnects with it.
Among the multiple initiatives to reduce temperatures in cities, the most effective ones are related to green infrastructure: trees, vegetation, more nature spaces, more urban greenery that provides shade and generates microclimates, and offsets CO2 emissions. This is what the Colombian city of Medellín did, creating 30 green corridors that reduced temperatures by up to 4 degrees by using easily maintainable native vegetation.
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Vitoria, the Lady of the Green Ring
In Spain, we find a recognized and recognizable case. It is the green ring that surrounds the Basque city of Vitoria-Gasteiz, a corridor of vegetation and biodiversity spanning almost a thousand hectares, which earned it the title of European Green Capital in 2012 and has improved the quality of life and well-being of its residents. The first interventions in this project date back thirty years. Today, this green infrastructure includes not only the ring itself but also parks, gardens, tree-lined streets and squares, urban orchards, streams, wetlands, green facades, and green roofs.
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Boeri: From Vertical Forest to Forest City
Throughout the world, comprehensive and impactful solutions have been developed, incorporating green infrastructure in both horizontal and vertical forms, projecting and constructing buildings capable of breathing anew. However, one of the most emblematic examples is perhaps the Vertical Forest, the two towers in the center of Milan covered with over two thousand plant species that amazed the world in 2014, designed by the Italian architect Stefano Boeri. It was an ambitious project of urban reforestation aimed at enhancing biodiversity through the vertical densification of greenery, mitigating the microclimate, and simultaneously reducing urban sprawl.
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The success of his proposal led him to develop more projects that explore the new relationship between the urban and natural spheres. One of his recent projects is a 29,000-hectare green neighborhood in Tirana, the capital of Albania.
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In his journey towards a new generation of urban architecture and cities capable of radically addressing the challenge of climate change, Boeri has also designed Forest City, a 21st-century forest mega-city planned to be built in the mountainous city of Liuzhou, southern China, one of the urban areas most affected by smog due to overpopulation
Forest City, will feature offices, houses, hotels, hospitals, and schools that will be almost entirely covered by plants and trees of various varieties and sizes. It will accommodate 30,000 inhabitants and function as a sustainable machine, capable of absorbing around 10,000 tons of CO2 and 57 tons of microparticles annually, while simultaneously producing approximately 900 tons of oxygen. By doing so, it aims to combat the serious issue of air pollution.
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Urban Silviculture
The architect and urban planner Carlo Ratti, is the director of Senseable City Lab del MIT. He believes that if the trend of incorporating vertical forests into cities is combined with agricultural greenery through hydroponic farming, urban gardens, and vertical farms (farms that climb the walls of buildings), the transformation of the city model would be even more radical. Alongside this urban forestry approach, another key aspect of future cities would be the consumption of locally sourced products and food sovereignty.
This is what architects Fei and Chris Precht propose. From their studio located in the mountains of Salzburg, Austria, they have developed a concept of modular, stackable, and flexible prefabricated homes made of cross-laminated timber (CLT), where homeowners can grow their own vegetables and herbs in vertical gardens. The project is called The Farmhouse and aims to reconnect people with agriculture and help them live in a more sustainable and healthy way.
R&D to drive transformation
New technologies are key to ensuring that the cities of the future contribute to the well-being of the planet. There are digital tools like Google’s Tree Canopy, which combines AI and aerial images to help cities assess their tree coverage and better plan reforestation efforts. It is already being used by around 350 cities.
Amsterdam, which is highly vulnerable to flood damage due to extreme rainfall, has an intelligent network of climate-adaptive roofs called RESILIO.
The project being developed in Aix Marseille Provence, the largest urban area in France where an estimated 70,000 people are exposed to pollution levels exceeding European standards, is called DIAMS. It involves creating an innovative air quality information system using 2,000 mobile sensors.
The MIT Senseable City Lab has also recently released an open-source and 3D-printable version of City Scanner, a mobile platform for free monitoring of air, noise, and heat in the environment.
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What do you think of these initiatives to adapt cities to extreme weather events? Let us know on social media using the hashtag #ConnectionsByFinsa, and if you found it interesting, don’t miss our articles on architecture in dry climates, wet conditions and icy habitat.
