Nature-based solutions: City greening reduces carbon emissions

A recent study published in the journal Nature Climate Change reveals that incorporating nature into city infrastructure doesn’t just capture carbon emissions, but it can also actively reduce them. The study was based on an integration of data from previous studies that examined the effects of various nature-based solutions. 

This finding implies that dozens of European cities could reach net-zero carbon emissions within the next decade by implementing a variety of green solutions such as parks, streetscaping, and roof gardens.

Focus of the study

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

“Phasing out fossil energy from transport, heating and cooling and other major emitting processes is key to achieving carbon-neutral cities,” wrote the study authors.  

“However, an issue often overlooked in energy systems and environmental engineering is how to spatially organize and use nature-based solutions (NBS), which can play a critical role in addressing the causes and consequences of climate change.”

“In terms of reducing carbon emissions, most attention has been paid to the direct effects, that is, carbon sequestration in vegetation, soil5 and wetlands6. However, it is estimated that carbon sequestration can offset only a limited proportion of total anthropogenic carbon emissions, especially in urban settings.”

How the research was conducted 

To investigate, the researchers analyzed the most effective approaches for natural carbon sequestration across 54 European Union cities. 

The study demonstrates that blending these nature-based solutions with other climate actions can not only help cities reach net-zero carbon but can also reduce emissions by an average of 17.4 percent.

Nature-based solutions 

Zahra Kalantari, an associate professor in Water and Environmental Engineering at KTH Royal Institute of Technology, highlighted the indirect ways in which nature-based solutions contribute to carbon neutrality. 

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

These solutions include urban farming, permeable pavements that enable rainwater absorption into the ground, narrower roads lined with more greenery and trees, wildlife habitat preservation, and the creation of more agreeable environments for walking and bicycling.

For example, urban parks, green spaces, and trees encourage more walking, bicycling, and other environmentally positive habits that replace automobile driving. 

Combined with other solutions like green infrastructure, these measures can improve urban microclimates by absorbing heat and cold, consequently reducing energy use in buildings.

Prioritizing green spaces

The study also provides guidance on which measures should be prioritized and where they should be located for optimal effect. 

Kalantari gave an example of how the study recommends prioritizing green buildings and urban green spaces in Berlin, 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 analyzes the potential systemic effect,” Kalantari said. “That’s new.”

This comprehensive approach suggests a promising path towards not just offsetting but reducing carbon emissions in urban areas by incorporating and prioritizing nature-based solutions as part of a broader climate action strategy.

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