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Initiatives

The fight of European cities against extreme heat: from trees to ecological restoration

The aim is to reverse the course that sees temperatures rising exponentially. The Italian and Spanish cases

by Davide Madeddu (Il Sole 24 Ore) and Ana Somavilla (El Confidencial, Spain)

30 June 2025

4' min read

The aim is, if not to reverse the course, at least to contain the effects of rising temperatures that sometimes make city life impossible. This is why in some communities in Europe, but also in Italy, work is being done to 'bridge the ecological gap'. This ranges from the creation of urban meadows to forest gardens and 'vertical greenery'.

A worrying situation

Experts speak of a 'worrying' situation because over the years temperatures have risen and this, in turn, triggers other reactions. "The average temperature has risen by 1.3 to 1.4 degrees compared to the pre-industrial period,' says Gianmaria Sannino, climatologist and researcher at ENEA. 'Since 2023 there has been a further acceleration and we are rapidly approaching the 1.5 limit that we should not have exceeded according to the Paris Agreement. In some cases the 1.5 degree has been exceeded but, as Sannino points out, there has been a return.

Rise in temperatures

The trend, however, is towards higher temperatures. 'A warmer world brings with it many consequences,' he adds, 'such as the extreme events that are heat waves. In the Mediterranean, the most obvious impacts are heat waves and the rising sea. Impacts that we are going to face. It must be said that what we are experiencing today was predicted by climatologists'. Should the degree and a half be systematically exceeded, the situation will become impactful. "In that case we will have heat waves that will last longer". All because, over the years, 'the natural climate system has been disrupted with large CO2 emissions'.

An hour's lunch in 4 seconds

"It is as if lunch and all the food consumed in an hour," the climatologist clarifies, "were eaten in four seconds. Let's just say that the atmosphere has had CO2 indigestion. We are now experiencing a climate change resulting from a storm to which the earth can only respond in one way, by raising the temperature'. For the expert, however, all is not lost because 'there is always a chance to give back a better situation to our children or grandchildren, it depends on both our behaviour and the choices of political decision-makers'.

Urban heat islands

And, in fact, following this path in several centres in Europe and also in Italy something is beginning to move.

Also because, in addition to the rise in temperatures linked to climate change, the so-called urban heat island phenomenon occurs in cities. "This phenomenon is caused by urbanisation," says Elisabetta Salvatori, head of integrated solutions for urban regeneration at ENEA's sustainability department, "and therefore by the fact that asphalt and concrete store heat that is released more slowly. This is why, also in the light of climate change, they are pursuing initiatives to bring nature back into the city and restore the nature of the soil with greenery'.

From meadows to urban forests

Against this backdrop we develop the various initiatives with 'different types of solutions, adapted to the context' ranging from trees to urban forests 'because trees are very effective in reducing temperatures and actively reduce air temperatures'. Other initiatives include 'micro forests of 150 square metres'. Not only that: 'Then there is the buildings game,' he argues, 'with roofs, facades'. One project that follows this path 'concerns the first municipality of Rome'. 'Fundamental in these projects,' the researcher adds, 'is the use of native species'.

The Italian case

In Italy, according to a 2021 study by Legambiente the percentage of trees in cities is highest in Turin with 47/100, followed by Milan 37/100. Lower down is Bologna with 21/100, Rome with 11/100, Palermo with 11/100 and Naples with 6/100. In Milan, as in Padua, the ForestaMi project envisages three million new trees throughout the metropolitan city. Other interventions are registered in Prato with the Forest City crowdfunding platform, an urban forestation project that also involves citizens. Projects also in Parma, Rimini and Mantua.

The Spanish case

Spain is also moving in the direction of greater urban sustainability, through initiatives that aim to renaturalise urban spaces and connect green areas. An emblematic example is the Bosque Metropolitano in Madrid, a green belt of more than 75 kilometres that will surround the capital with forest areas, bicycle and pedestrian paths and ecological restoration work. This is an ambitious project involving citizens and private companies, which aims to reduce the impact of heat islands and promote biodiversity.

In parallel, other cities such as Valencia and Seville are transforming old disused infrastructure, such as riverbeds or abandoned railway tracks, into green corridors that promote natural cooling and ecological connection. Seville, in particular, already has more than one hundred parks and green areas scattered throughout its urban territory.

Also in Madrid, the renaturalisation project of the Manzanares River, launched in 2016, is worth mentioning, which has allowed part of the ecological dynamics of the urban watercourse to be restored. The opening of dams and the removal of some channels have allowed the return of native vegetation and numerous animal species. According to a study by the Autonomous University of Madrid, the number of floral species present along the urban stretch of the river has doubled.

There is no shortage of educational and social initiatives related to urban ecology. School and community gardens are spreading in many Spanish cities: gardens that not only transform roofs and courtyards into productive spaces, but also play an important role in promoting inclusion and environmental awareness. The Ministry of Ecological Transition emphasises how these projects are able to regenerate degraded areas, encouraging the direct involvement of citizens. Exemplary in this sense are the urban garden 'La Cabaña del Retiro' in Madrid, dedicated to students and the elderly, or 'El Caminito' in Malaga, managed by an association with educational and social aims.

However, strong territorial inequalities remain. According to Pablo Moreno, a researcher at the University of the Basque Country, "urban planning in Spain is taking climate change into account, but there is a clear difference between cities that invest in research and innovation, such as Madrid, Barcelona or the Basque Country, and those that do not have funds or research capacity." Moreno also points out that "social measurement is almost more important than the level of innovation", highlighting the crucial role of civic participation in urban design and the management of green spaces.

*This article is part of the European collaborative journalism project "Pulse".