Our cities are simply not ready for the future. Climate change is not a distant threat, it's already happening, and the impact is affecting people where it matters the most: in their homes, in their streets, in their communities. Hotter summers, increased rainfall and more frequent storms are affecting the health and safety of urban populations. The question is not simply whether cities should adapt, but whether they will survive as places where people want to live, work and thrive.

For centuries urban nature has been on the agenda for city planners, developers, and policy makers. But all too often, it has been treated as a decorative afterthought. This approach is, at best, outdated, at worst, perilous. Urban nature is not a luxury; it is a life-support system.

Now, we must move beyond treating nature as a “nice-to-have” and instead embed it as a non-negotiable. It is physically impossible to meet our climate and social ambitions without integrating nature into the fabric of our cities. We need to develop a radically different approach. Without nature, our infrastructure is fragile, our economies are exposed, and our communities are at risk. 

Beyond green roofs 

A single green roof or individual park is not going to protect a city from the next flood or heatwave. What’s needed is a radical shift – a whole-system approach that recognises cities as ecosystems in their own right. 

Consider Singapore, where green corridors and rooftop gardens are woven into the city’s DNA. Or Copenhagen, where stormwater parks double as community spaces and flood defences. These cities aren’t just surviving climate shocks, they’re thriving because nature is built in, not bolted on. They demonstrate that when urban nature is treated as vital infrastructure, resilience and wellbeing follow.

The real cost of inaction 

Every year, floods and heatwaves cost cities billions in damages, lost productivity, and rising insurance premiums. But the true cost is measured in lives disrupted, health compromised, communities fractured and worst of all, lives lost. Vulnerable populations, those without air conditioning, those living in flood-prone neighbourhoods, pay the highest price. 

Investing in urban nature is not just about aesthetics or biodiversity. It’s about protecting people, stabilizing economies, and future-proofing cities. It is imperative to weigh investments in natural urban systems against the expenses of heat-related deaths, flood damage, and food insecurity. The High Line in New York transformed a derelict rail line into a vibrant public space, boosting local business and property values. Barcelona’s superblocks have dramatically reduced air pollution and reclaimed the streets for people, not cars. These examples are blueprints for what’s possible. 

Project
Newham Just Transition Plan
Learn how Arup helped the London Borough of Newham design a Just Transition Plan that accelerates its net zero ambitions while creating a fairer, healthier future for its communities.
A boy kneeling in a field of hay.

Who pays for a liveable city? 

Two major obstacles hinder urban greening: the tendency to delay action and the complexity of coordinating multiple stakeholders. In truth, the benefits of urban greening are shared, but the costs often fall on the few. Property owners, developers, and city governments wrestle with who should foot the bill. Retrofitting old buildings and neighbourhoods is complex, but the alternative of deepening inequality and declining liveability is far worse.

The answer lies in collective action. We must rethink funding models, drawing on public and private investment, and treating green infrastructure with the same seriousness as transport or utilities. Collective involvement means that everyone benefits. The risk is that our cities won't be viable if we do not make a shift. 

Listen to our experts

Tom Butterworth explores the priorities we must address if our cities are to become functional, healthy ecosystems.

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Managing an ecosystem requires a whole-system approach

Cities, though young ecosystems, generate their own climates, regulate water, and host diverse species including humans. Unlike natural habitats that require protection, cities demand conscious design to integrate built environments with natural processes.

This matters because viewing cities as ecosystems changes how we act. Water should be slowed and absorbed like a catchment, not flushed away through hard drains. Soils need to be managed as living systems, not treated as inert ground to be sealed beneath concrete. Green space should be connected so both people and other species can move safely, and all of us need to be recognised as part of the ecosystem as co-creators, not external observers.

In our sponge city research, we model how slowing and holding water reduces flood risk at scale. Our urban heat research can guide planting and cooling interventions in the hottest parts of the built environment, for cities really struggling with rising temperatures.

Project
Bristol One City Climate Strategy
Discover how Arup partnered with Bristol City Council to co-create an inclusive climate strategy driving the city toward carbon neutrality by 2030.
A park in Bristol

Planning for change – cities as dynamic habitats 

Another factor to consider is the fact that urban ecosystems are never static and need to be approached with this in mind. They’re evolving, adaptive environments, that, if managed wisely, can become more resilient over time. Foxes in London, falcons in Tokyo, and community gardens in Seattle all tell the same story: nature finds a way, even in the heart of the city. But it’s up to us to design cities that welcome and nurture this diversity.

A societal shift is needed to value less manicured, more natural green spaces for their true ecological and social benefits. Consider the historical resistance to building sewers - what was once controversial is now essential.

The risks are real, the stakes are high, and the time for half-measures is over. Cities must be recognised, designed, built and managed as living systems, where nature with other types of infrastructure work together to support life. This is not just an environmental agenda, it’s an economic, social, and moral imperative.

Professionals across public and private sectors must champion urban ecosystem thinking. It’s time to move beyond consultation and towards co-creation, where communities, businesses, and governments work with nature to share responsibility for a sustainable urban future

Let’s stop asking if we can afford to invest in urban nature. The real question is: can we afford not to?

Project
Wild West End
Explore Arup's partnership with seven of London’s largest landholders, working towards a shared vision of creating a world-first in-urban greening.
Greening the city in London

Mastering the ecosystem – a task for everybody 

We need to see engagement between advocates and experts, to promote urban ecosystem thinking in their communities, fostering nature as infrastructure through whole-system thinking and collaboration. Here at Arup, we are encouraging ongoing dialogue, collaboration and advocacy to shape the transformation of cities into thriving ecosystems. Come and talk to us about the importance of collective effort and adaptive management for a sustainable urban future.