Nature-based solutions needed to create climate-neutral cities

Climate neutral cities, also called carbon-neutral cities, cannot be created solely by technological means. Nature-based solutions are required as well, according to a new study in Nature Climate Change based on satellite data from 54 European cities.

A carbon-neutral city absorbs the same amount of carbon dioxide as it emits.

“Separately, neither nature nor technology can make cities carbon neutral. We need to combine these. Clearly, carbon-neutral cities are a prerequisite to halt global warming,” says Stephan Barthel, professor in environmental science.”

Stephan Barthel, Johan Colding, and Patrik Thollander, researchers at University of Gävle, in collaboration with colleagues from KTH, Stockholm University, and Shanghai University, have developed a model that can determine the potential of nature-based solutions to reduce emissions in 54 European cities. The model, based on satellite imagery and remote sensing data, can also tell us where to locate plantings to achieve maximum effectiveness.

Examples of nature-based solutions include investments in green roofs, the creation of green spaces and parks, and planting trees to form avenues on heavily trafficked streets.

“People tend to stop cycling when it gets too hot. However, by planting trees whose canopies provide shade along paths where many people move, the climate becomes more comfortable, allowing individuals to continue cycling instead of using cars, which in turn reduces emissions. Many examples of this approach in Southern Europe show that this has an impact," says Stephan Barthel

But even if nature itself is important, technological solutions are crucial in creating carbon-neutral cities.

“Nature-based solutions have the potential to reduce carbon dioxide emissions by up to 25 percent. The study shows that cities such as Nicosia (Cyprus), Zaragoza (Spain), and Plovdiv (Bulgaria) can achieve carbon neutrality before 2030. Other pioneering cities include Amsterdam, Copenhagen, Helsinki, and Stockholm, which are estimated to be very close to achieving the goal of carbon neutrality through nature-based solutions, provided that their respective technical roadmaps for phasing out fossil fuels are followed," says the study’s lead author, Haozhi Pan, from Shanghai Jiao Tong University.

Now, the researchers hope that the study can be used to help nature-based solutions gain prominence in EU policy documents aimed at realising carbon-neutral cities.

“Today, there are no nature-based solutions in the policy document. However, our study proves that they are required to reach the goal of carbon-neutral cities. In most cases, a combination between various locally adapted green solutions and urban planning is needed for maximal effect,” Stephan Barthel says.

Link to scientific article External link.