Nature Based Solutions: Greening Europe’s Cities for Climate Resilience

Nature-based solutions (NbS) integrate natural elements into urban design to address climate and social challenges. The European Commission defines NbS as “solutions that are inspired and supported by nature, which are cost-effective, simultaneously provide environmental, social and economic benefits and help build resilience”.

These systems work with ecological processes. For example, by cooling the air, capturing stormwater, improving air quality and boosting biodiversity, while also creating recreation and community space.

What are nature based solutions in cities

In urban planning, nature-based solutions (NbS) involve using natural processes to solve urban problems. They bring nature back into cities through parks, green corridors, wetlands, rain gardens, street trees, green roofs and similar features. By tapping ecosystem services, NbS complement or substitute traditional “grey” infrastructure. For example, restoring an urban wetland can attenuate floods instead of enlarging a concrete sewer, or planting a line of trees can cool a street rather than installing air-conditioning. NbS benefit biodiversity while delivering multiple services (shade, filtration, recreation, carbon capture, etc.).

Why european cities need nature based solutions (including equity)

Cities are on the front lines of climate change. Nearly 70% of Europeans already live in urban areas, and this figure is growing. Concrete and asphalt make cities heat islands with often several degrees warmer than surrounding countryside. Sealed surfaces and fast runoff worsen flooding. Recent record heatwaves and floods across Europe have exposed these vulnerabilities. Europe’s climate agencies note that urban centers saw unprecedented heat in 2023, with cascading impacts on health, energy and water systems.

NbS also address social equity. Wealthier neighborhoods often have more parks and tree cover, while disadvantaged areas can suffer higher heat and flood risk. By strategically creating green space in underserved areas, cities can narrow these gaps. For example, studies show that proximity to parks and trees correlates with better health and lower stress.

Urban parks and street trees are “nature-based solutions” that provide multiple benefits: they clean air, ease stormwater pressure and lower urban temperatures.

Vivid examples of nature based solutions in cities

Below are representative NbS projects and practices. Each example shows how cities use nature to solve problems of heat, flooding or poor air, often with aesthetic and social gains.

Urban Forests and Street Trees

Planting trees and creating urban woodlands is one of the most direct NbS. Street trees and park forests provide shade and evapotranspiration that cool streets on hot days. They also capture CO₂, reduce energy use (e.g. by shading buildings) and filter pollutants from the air. Indeed, experts often note that cooling cities with trees is an easy win. NbS can take the form of linear tree plantings, forest patches, or even ‘pocket’ forests in vacant lots. These green corridors enhance biodiversity by linking city and countryside.

Beyond planting, cities now use technology for urban canopy mapping. Satellite imagery and aerial LiDAR allow municipal foresters to measure existing tree cover over whole neighborhoods. This reveals gaps where canopy is below 30%, a threshold linked to heat reduction, and guides where to plant.

Parks, open spaces and water management

Large green spaces (parks, lakes and restored wetlands) serve as communal green lungs and sponges in cities. They absorb stormwater, reducing flood peaks, and provide cooling. A striking modern example is Rotterdam in the Netherlands, which has built several “water plazas”. These are multifunctional public squares that act as basins during heavy rain. In dry weather they function as playgrounds or recreation spaces; when storms hit, their paved areas collect runoff and store it underground, preventing flooding in surrounding streets. Similarly, the Dutch Room for the River programme has restored river floodplains around urban areas to give rivers more space during high flows.

Green roofs and vertical gardens

When horizontal space is limited, cities go vertical or up. Green roofs (vegetated roof gardens) and living walls (climbing plants or vertical planters on facades) turn buildings into climate tools. A layer of plants and soil on a roof provides insulation (lowering energy use) and slows rainwater runoff. It also creates pollinator habitat. For example, Copenhagen’s municipal program has installed thousands of green roofs, which improved building insulation and reduced stormwater runoff while creating wildlife habitat.

Germany is another leader in building greening. Freiburg and Stuttgart encourage green facades; Freiburg’s eco-quartiers feature extensive rooftop gardens. In Stuttgart, The Nature Conservancy helped pilot “wild climate walls” – a type of living wall using native plants and insect hotels on building walls

Measuring green equity and cooling with the 3+30+300 rule

To translate NbS goals into action, cities need clear targets. The “3-30-300” rule, conceived by urban forestry expert Cecil Konijnendijk, is a useful guideline for equitable greening. It specifies that:

1. Three trees visible: Every person should be able to see at least three trees from their home or workplace.
2. Thirty percent canopy: Each neighborhood should aim for at least 30% tree canopy cover.
3. 300 metres to a park: No residence should be farther than 300 m (about a 5-minute walk) from a public green space.

This simple framework embeds equity: the three-tree view ensures greenery even at the street level, 30% canopy sets an ambitious shade goal, and a 300 m rule guarantees park access for all.

Many cities currently fall short of these benchmarks, especially in dense or low-income districts. Achieving 30% canopy may require decades of planting and protecting mature trees. Likewise, acquiring land for new parks can be hard. That’s where data and planning tools come in. Cities now use satellite imagery and GIS to map current tree cover and identify gaps.

Miloslav Kaláb

ASITIS.cz, Climate Resilience Specialist

UpGreen by ASITIS – Data-driven nature based solutions for cities

UpGreen uses orthophoto and satellite imagery to map 100% of a city’s green spaces, not just public parks, but private gardens, street trees, lawns and forests. The tool assesses the vitality and density of all vegetation, classifying each area by condition. In effect, UpGreen turns satellite pixels into detailed map layers of urban green cover.

Get the 3-30-300 Green revolution handbook and the full Copenhagen UpGreen report

References: Key references include the European Commission and EEA reports on NbS (climate-adapt.eea.europa.eueuronews.com), the ASITIS analyses of the 3-30-300 rule and UpGreen tool (asitisready.com), case studies and guides by the Nature Conservancy (nature.org), and the EIB’s report on investing in NbS (eib.org). Additional examples are drawn from EU initiatives (e.g. Urban Nature Atlas (research-and-innovation.ec.europa.eu) and recent urban NbS projects in cities like Copenhagen, Rotterdam and Stuttgart (ppo-engineering.eu).