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By Roger Highfield on

Greening cities helps achieve net zero within a decade

Cities can play a key role in mitigating climate change, according to a new study.

By incorporating parks, trees, roof gardens and green spaces, a new study suggests that dozens of European cities could reach net zero carbon emissions over the next decade, with a handful of pioneering cities already on track for carbon neutrality.

Published in the journal Nature Climate Change, the analysis by researchers from Sweden, the United States and China shows the ways cities harness green solutions can capture carbon emissions and help curb them.

Not just a cool and shady oasis in the city, Stockholm’s Karlavägen contributes to climate-positive behaviors such as bicycling and walking. Source: David Callahan/KTH Royal Institute of Technology.

The study recommends the most effective approaches for natural carbon sequestration in 54 cities. And it shows how prioritising different nature-based solutions could cut emissions by an average of 17.4 percent.

When added to other measures, such as using renewables and boosting energy efficiency, they estimate total carbon emissions could be cut by almost 60 per cent by 2030, and that some pioneering cities might achieve carbon neutrality by then, notably Amsterdam, Copenhagen, Helsinki, and Stockholm (UK cities fell outside the study, which focused on the EU alone).

Zahra Kalantari, an associate professor in Water and Environmental Engineering at KTH Royal Institute of Technology, Stockholm, says the researchers investigated the indirect ways that ‘nature-based solutions’ contribute to carbon neutrality.

‘Nature-based solutions not only offset a proportion of a city’s emissions but can contribute to reduction in emissions and resource consumption too,’ Kalantari says.

The results are based on integrating data from previous research on the effects of nature-based solutions, including permeable pavements which boost rainwater and stormwater absorption into the ground, narrower roads with more greenery and trees, wildlife habitat preservation, green belts to curb urban sprawls, and designing cities to encourage more walking and bicycling, for instance by introducing more parks.

The study also provides guidance on which measures should be prioritized and where to locate them for the best effect, she says. For example, in Berlin the study recommends focusing on green buildings and urban green spaces, which could result in an emissions reduction rate of 6 percent for residences, 13 percent in industry and 14 percent in transportation.

‘There are many studies that examine the effects of individual nature-based solutions, but this merges all of them and analyses the potential systemic effect,’ she says. ‘That’s new.’

While the study focused on the EU, it has important lessons for elsewhere, notably in India and China where new cites are being built, such as Palava near Mumbai.

View of Palava, India. Credit: Lodha.

‘Although this study was limited to the EU for data consistency reasons, the cities included represent a wide variety of geographical, climatic, and socio-economic conditions,’ she says. ‘Our finding was that nature-based solutions can be effective to varying degrees for reducing net emissions in all of these cities, but that the strategies need to be carefully selected according to local conditions in order to achieve the best effect.’

She adds: ‘cities striving to achieve net-zero emissions should consider incorporating these kinds of nature-based solutions into their climate action plans, keeping in mind that it’s very important for these solutions to be tailored to each city’s own unique conditions for maximum effectiveness.’

The study was a collaboration between researchers from KTH Royal Institute of Technology in Stockholm, MIT, Stockholm University, University of Gävle, Linköping University, Royal Swedish Academy of Sciences and Shanghai Jiao Tong University.