Vertical forests and urban rivers can transform city life, writes Jonny Hughes

Achieving truly sustainable cities is one of the great global challenges of the 21st century. The United Nations expects the proportion of people living in cities will increase from about 54 per cent in 2017 to an estimated 66 per cent by 2050.

During that time the world population is expected to increase from 7.5 billion to 9.5 billion people. The scale of urban growth needed to accommodate such an increase is the equivalent of more than 250 times the size of London or about the size of Mongolia. Most of this growth will occur in developing countries, but many developed nations will also experience expansion, particularly in larger cities.

The way in which this expansion takes place will determine not only the physical character of towns and cities, but also our ability to live healthy, peaceful and prosperous lives.

Urban areas are where many of the impacts arising from environmental change will be felt most acutely. Climate change-induced flooding and severe heatwaves already disproportionately affect towns and cities. Anticipating change now and making design decisions that build resilience in urban environments could help us cope better with climate shocks. For these design solutions to be successful, a fundamental rethink about how we perceive cities is required. This means seeing them as ecosystems in their own right rather than separate and distinct from the geology, soils, water and natural habitats they are built upon. Such natural features are often still evident even in the most intensely urbanised areas – Arthur’s Seat in Edinburgh and Glasgow’s Cuningar Loop are two examples close to home.

In a new publication, the Scottish Wildlife Trust has proposed a new design approach called ‘ecological urbanism’, which seeks to enhance cities’ underlying natural foundations to help create great places where people and nature can co-exist to mutual benefit. A compelling body of evidence has emerged that has revealed the many benefits to be gained from conserving and enhancing nature in cities. These include improved physical health and well-being, reduced flood risk, cleaner air and water, enhanced inward economic investment and even longer life expectancy. Ecological urbanism seeks to fully realise these benefits by blending green areas – parks, gardens, rivers, street trees and green roofs and walls – with grey urban infrastructure. But ecological urbanism is not simply about more greenspaces. It is about the densification of built-up areas to reduce sub-urban sprawl and the artful integration of green infrastructure in streets.

In Scotland, we could draw inspiration from innovative urban greening projects around the world. Seoul removed a traffic-choked elevated motorway from the city centre and restored a 3.6-mile river corridor that now attracts over 60,000 visitors daily and has catalysed economic development. Milan has built a vertical forest in the heart of the city in the form of two residential towers with an incredible 900 trees and 5,000 shrubs.

It would be great to see such flagship projects in Scotland but what could be even more transformational is if every city dweller here took one simple step to re-wild their neighbourhood. Thousands of small actions from scattering wildflower seeds to growing vegetables in window boxes could, when taken together, have even greater benefits for people and nature than Milan’s famous Bosco Verticale.

Jonny Hughes is Scottish Wildlife Trust’s chief executive. Follow him on Twitter @Jonnyecology