Caring Cities: Why We Need More Green Spaces, Innovation, and Consensus

Discover why greener, more innovative, and people-centered cities are key to tackling climate, health, and equity challenges in urban environments.

Today more than ever, our cities face major challenges: more extreme temperatures, polluted air, sedentary lifestyles, and social and environmental inequalities.

The good news is that many solutions are within reach. We know (because we've studied, modeled, and observed it daily) that adding more greenery to the urban environment improves health, well-being, and quality of life. From global-scale analyses to local studies, the results are consistent: greener cities are cities that care better.

Planting trees is not enough. What matters is how green spaces are integrated into the city, who benefits, what additional advantages they bring, and how they align with other urban policies.

In a study we conducted in 93 European cities, we estimated that a significant portion of excess summer mortality is due to heat accumulation in urban areas with little green cover. But we also found that if a 30% tree canopy cover were achieved, up to a third of these deaths could be prevented.

Lavínia School in Barcelona. Photo: Barcelona City Council / Àlex Losada.

And there are additional benefits: reduced stress, improved mental and physical health, increased physical activity, lower air pollution exposure, and greater activation of public spaces.

Barcelona as an Urban Planning Laboratory

Barcelona is a great example of how a city can experiment with urban models that aim to deliver multiple benefits simultaneously. Our team has evaluated several of these initiatives.

1. One of the most iconic cases is the Superilles (or Superblocks) strategy, which limits vehicle traffic in groups of city blocks to prioritize pedestrians, bicycles, and community activities. Our research shows that this model improves air quality, reduces urban noise, and promotes physical activity. If extended city-wide, the health impact could be considerable.
2. We also analyzed the potential of the Green Axis Plan if implemented city-wide. Although a first phase was completed, its expansion was cancelled due to political changes. The plan aimed to green one out of every three streets, implying a moderate increase in green surface (about 3.6%). Still, our findings suggest that if fully carried out, the intervention could prevent up to 178 premature deaths annually, mainly due to its spatial distribution.
3. But the impact goes further. In another study, we found that this same urban transformation could also significantly improve mental health: nearly 14% of mental health problems could be prevented each year, along with a 13% reduction in antidepressant use and an 8% drop in tranquilizer use. Additional benefits for children are expected as well, such as more space for free play, more physical activity, and greater independence in the urban environment, which could foster behavioral and cognitive development. In this context, a 5% drop in hyperactivity cases and a 6% drop in attention problems have been estimated.
4. We also estimate that the Green Axis initiative could reduce thermal stress during the hottest months by up to 1.5 ºC, with a positive impact on health and well-being. At the same time, it could help reduce air conditioning use, which not only emits more heat into the environment but also increases carbon emissions.
5. More recently, we have begun assessing the potential impact of the green roof program promoted by the city council. This strategy aims to green rooftops, improve thermal insulation in buildings, and boost biodiversity in areas where there is limited soil available for vegetation.

It’s Not Just About Planting More Green

One of the common conclusions across all these studies is that planting trees is not enough. What matters is how greenery is integrated into the city, who it reaches, what other benefits it generates, and how it connects to broader urban policy.

New park at Les Glòries. Photo: Josbel A. Tinoco.

We propose a comprehensive approach: more greenery, yes, but also more walkable streets, better infrastructure to support public space use, more parks for leisure, more transformed schoolyards, and more spaces designed with and for the people.

We propose a comprehensive approach: more greenery, yes, but also more walkable streets, better infrastructure to support public space use, more parks for leisure, more transformed schoolyards, and more spaces designed with and for the people.

Well-designed interventions allow us to make progress on multiple fronts at once: health, mobility, sustainability, and social inclusion. The key is to plan them together, in an integrated way and with a long-term vision.

Area around the Can Framis Museum in Barcelona. Photo: Curro Palacios.

What’s Missing?

We have the evidence, the data, the technical know-how, and real-world examples. What’s often missing is the next step: political will, a shared vision, and genuine and sustained public participation.

Transforming a city is not just a matter of budget or technical design (though these are very important!). It’s a collective decision.

Transforming a city is not just a matter of budget or technical design (though these are very important!). It’s a collective decision. It requires broad agreements, bold institutions, and a committed citizenry defending their right to a healthier, fairer, and more resilient city.

A City That Puts People First

This World Environment Day is a great opportunity to reflect on the kind of city we want to build. A city that is not just environmentally “greener” but more livable in our everyday lives.

Because a caring city doesn’t appear on its own — it is designed, implemented, and defended by all of us, together.