As climate change gets worse and cities grow fast, we are losing more and more natural spaces. Birds, bees, butterflies, and plants are disappearing quietly but quickly. Cities that once had green parks and gardens full of life are now full of grey buildings and roads.
This isn’t just about nature, it’s about our own future too. Nature gives us clean air, water, food, and joy.
Nature-based solutions (NBS) are smart ways to bring back nature into our cities. These include things like turning empty schoolyards into green spaces, planting forests, making space for rivers to flow naturally, and using green roofs.
They help cool cities, reduce floods, improve health, and bring back biodiversity all the different plants, animals, and insects that make nature strong.
But just planting a few trees or building one pond is not enough. We need to do much more than that.
A new study, published in May 2025 in the journal Discover Cities, explains this clearly. The research was carried out by Carolyn Petersen, Duncan Russel and Nick Kirsop-Taylor from the University of Exeter, UK and Anne Jensen and Anders Branth Pedersen, from Aarhus University in Denmark. The study is part of the REGREEN project, funded by the European Union’s Horizon 2020 programme.
The researchers looked at how three cities used NBS: the Paris Region in France, Aarhus in Denmark, and Velika Gorica in Croatia.
Nature-based solutions are tangible, multi-functional, nature integrated policy interventions that restore or enhance ecosystems to address societal challenges like climate change, biodiversity loss, urban heat and flooding by greening schools or restoring rivers and wetlands, or urban rewilding.
NBS are not one-off cosmetic fixes like just planting trees without strategic planning. They are not like market-based biodiversity, offsetting schemes or biodiversity credits which often aim to compensate rather than restore nature.
The study stresses that NBS should not be reduced to green-washing infrastructure projects.
The study used semi-structured interviews with local government staff, environmental non-profits, urban planners, community groups and academic stakeholders and three policy workshops with policy implementers, civil society actors, consultants and regional planners were done in 2021 and 2022.
The researchers found that NBS works best when they are part of big plans that link climate, health, and infrastructure and not small one-time projects.
In cities where leaders supported NBS and people helped from the beginning; nature came back strongly.
In Aarhus, forests were planted near the city, not just rows of trees, but full of wildflowers, small lakes, and streams. These places were made with help from local people and were open for everyone. These became homes for birds, insects, and many plants.
In Paris, schoolyards were changed from hot concrete into green areas using native plants. These small spaces became mini-nature zones. People also started their own green efforts like community gardens and planting in empty corners without waiting for government help.
In Velika Gorica, some good work had started like fixing rivers and putting gardens on roofs. But it was slow. Decision-making was tightly controlled, and there wasn’t enough money. Even when ideas were good, they didn’t move forward because of delays and lack of support.
NBS are not just for beauty. They help bring back life, like bees, frogs, butterflies, and birds. All of these are part of the natural web we depend on. But to really help nature, these projects must be part of bigger plans.
They should be linked to city planning, health systems, and climate action. They should not be done just to “tick a box.”
The study found that when biodiversity is treated as just an ‘extra’, we get parks that may look clean but are lifeless. But when biodiversity is the main goal, cities become richer in nature and more resilient to climate change.
To do this, different departments like water, health, environment, and planning must work together. Not separately.
Even in cities that want to do better, there are problems, the researchers found. Many leaders only look for quick wins. They don’t plan for the long term. Funding often stops after the first phase. Rules around construction and buying materials still favour concrete over trees.
In Velika Gorica, a few top officials made most decisions. Even when people had good ideas for nature, they didn’t go far because of bureaucratic red tape and lack of funds.
In Aarhus, the local government had more freedom and support to try new ideas, and they made it work.
The researchers say that it is important to make biodiversity a core urban goal, not an add-on. This means policies must spell it out clearly.
Fund long-term projects, not just pilots. Biodiversity takes time to grow.
Support community-led nature efforts. The best ideas often come from the ground up.
Break the silos. Planning, climate, and nature teams must work together, not against each other.
Train leaders to be bold. It takes guts to prioritise birds over buildings, wetlands over roads.