There is no doubt that creating green spaces in cities brings many benefits. These include purifying the air of particulate matter, absorbing carbon dioxide, reducing the risk of flooding, and creating opportunities for recreation, to name just a few. What may surprise many enthusiasts of urban greenery, however, is that the value of these benefits can actually be measured. Environmental economics is a field of study that examines the value of services provided by ecosystems. Dr. Zbigniew Szkop from the Faculty of Economic Sciences at the University of Warsaw, a leading center for this discipline in Poland, specializes in “green accounting.”
Calculating the “uncalculable”
However, calculating the salary of a tree is not so simple. “Ecosystem services” are not traded on the market, which means they do not have a specific price. At the same time, this opens the door to scientific calculations and estimates. Environmental economists determine the value of services provided by urban greenery based, among other things, on so-called surrogate markets. In other words, they use data on products or other market services that are directly related to ecosystem services.
For example, when estimating the value of trees’ ability to purify the air of particulate matter, researchers examine the costs generated by polluted air – such as health problems or reduced work efficiency. Health problems across the population translate into higher healthcare costs. By determining how high those costs would be, economists can assign a specific value to the service provided by trees.
From seedling to millionaire
Dr. Szkop’s team has developed an innovative tool: the “Urban Tree Ecosystem Services Calculator.” It makes it possible to estimate the benefits provided by urban greenery. For example, according to estimates, a street tree growing in a large city with a trunk circumference of 50 cm will generate benefits worth at least PLN 5,862 over the next 10 years. And that’s just one tree.
Dr. Szkop has been conducting research in Polish cities for nearly a decade, demonstrating the substantial benefits that investments in urban greenery can bring. By 2023, his team had conducted more than 80 studies, both in large urban areas such as Warsaw, Poznań, and Rzeszów, and in smaller towns such as Lidzbark Warmiński, Przasnysz, and Szczytno.
“In many cases, these studies have changed the perception of urban trees – they are now seen not only as a cost, but as an investment with a high rate of return,” notes Dr. Szkop.
For example, his research conducted in Przasnysz together with Prof. Tomasz Żylicz showed that the value of the benefits provided by trees growing in seven urban green areas included in the study amounts to PLN 1.7 million. Meanwhile, a study conducted in Rzeszów showed that the 1,555 trees included in the research generated benefits worth PLN 6.5 million.
Importantly, the presence of trees also has a positive impact on the value of nearby real estate. In the case of Rzeszów, property prices increased by as much as 3%.
Cities want to invest in trees
The data clearly shows that creating green spaces in cities simply pays off – economically as well. The results of research conducted by Dr. Szkop’s team may encourage local decision-makers to focus more strongly on developing green infrastructure.
After all, despite growing environmental awareness, there are still situations in Polish cities where fewer trees are planted than are cut down. However, Dr. Szkop – who has worked for years with local governments, non-governmental organizations, public institutions, and businesses – has observed a change in how local decision-makers approach urban greenery:
“In recent years, local authorities have become increasingly interested in collaborating on the valuation of ecosystem services provided by trees in their cities. Perhaps this is because they recognize that such analyses can significantly support the development of Municipal Adaptation Plans. The number of such plans is constantly growing. More than 100 cities already have such documents, and in the coming years all cities with at least 20,000 residents will be required to adopt them,” the scientist comments.
Green is cool
Dr. Szkop’s team is currently working on a much more advanced planning tool as part of the LifeCoolCity project, co-financed by the European Union. The tool is designed to support city officials in managing urban greenery as effectively as possible. It will help determine where creating new green spaces will bring the greatest benefits to both the city and its residents. Research using this tool is currently underway.
“Wrocław will be the first city for which a concept for the redevelopment of blue-green infrastructure will be developed using this tool. The results of the analysis will be known by the end of next year. It will be the largest analysis of its kind in the world,” emphasizes Dr. Szkop.
By Zbigniew Szkop, University of Warsaw.
The text was originally published in Polish on the Serwis Naukowy UW website on February 14, 2025.
