Adapting our green spaces for a changing climate

The UK Met Office released a weather forecast for the year 2050 predicting hotspots to reach 43°C during the day and 24°C at night. Urban temperatures in 10 major UK cities will increase significantly, resulting in heat stress, risk-to-life warnings, and peaks in water demand. More frequent and extreme temperature increases cause urban heat-island effects.

In the US, according to the Center for Public Integrity, extreme heat killed 10,000 people between 1999 and 2016. That made climate-induced heat more deadly than hurricanes, tornadoes, and flooding.

Today, when we design, we must consider heat impacts on our infrastructure, energy system, environment and nature, our health, and way of life.

Trees, trees everywhere

Let’s start with our trees—the “lungs of the earth.” We see reforestation projects across the globe and tree planting serving as a popular carbon offsetting option. But what happens when climate-induced weather extremes wipe out newly planted saplings? Or the leaves of native trees in the summer die and lose their cooling effect because of intense heatwaves? And remember, it takes years for a sapling to develop its full carbon-capturing potential. 

A new study published in Nature Climate Change shows that climate change is putting trees in cities and towns at serious risk. Multiple species—including cherry plums, oaks, maples, poplars, elms, pines, lindens, wattles, eucalyptus, and chestnuts—are threatened. Trees in India, Niger, Nigeria, Australia, and Togo are particularly vulnerable.

In the face of rising temperatures, researchers call for more measures to protect our trees and to plant special drought-resistant varieties. Initiatives to help the survival of urban forests include rainwater harvesting for watering of plants and trees, encouraging gray water use for gardens, planting more trees and shrubs in our local areas, and leaving trees where they are rather than removing them.

But there are areas we need to improve. These include funding and who looks after our green infrastructure assets once installed—from sustainable urban drainage systems to green corridors, trees, and shading options. Planting thousands of trees is one direction, but our responsibility doesn’t stop at filling in the hole with soil and putting down the shovel.

Our green cities—present and future

If we don’t want ghost-like and uninhabitable cities during summer months, city planners must manage urban heat-island effects. By regenerating urban design to incorporate green-blue infrastructure and vegetation-clad buildings, we can reactivate the worst heat island cities.  

The idea is to make our early century gray infrastructure transportation routes a thing of the past. They should no longer dominate urban areas, nor dictate the design process. In cities like Barcelona, Spain; Strasbourg, France; Frankfurt, Germany; and Birmingham, UK, trams traverse along beds of grass on their city circuits. This blending of public transport with heat-proofing landscaping should be part of our urban fabric and design processes. Connecting our urban floodplains and woodlands will incorporate movement and cooling effects into our infrastructure.

Look up as you take a walk around places like Singapore and Milan, Italy. There you will see the concept of vertical greening in action. Green infrastructure is a critical part of life in these cities. On a Sustainable Walking Tour around London, UK, there are buildings that are steadily being retrofitted to include living walls, green roof spaces, and green courtyards. They will help capture rainfall, increase biodiversity, clean polluted air, and provide a sense of well-being. London is the world’s first National Park City, and Mayor Sadiq Khan aims to turn over 50% of the city to green by 2050 (it is currently at 47%). 

From improved planning policy proposals to community-owned gardens, the rise in regenerative urban greening means building places and spaces that are more than just a pretty green space. They must adapt to rising temperatures and wetter seasons.  

Using living systems for resilience

Planning for a warmer future means exploring ways to replace or enhance our conventional designs with “living systems” that protect us against storm surges but don’t render our waterfronts ugly, prohibitive, and unwelcoming. Living systems can make our neighborhoods beautiful, habitable, and resilient. They also contribute to reducing carbon through nature-based solutions. Other examples are floodplains that capture excess water, yet can still retain it in the height of summer, and waterfronts that protect from coastal erosion while enhancing biodiversity and provide active travel routes. 

Living systems are most often accompanied by aesthetic, recreational, or habitat benefits. They provide park space and natural beauty that is appreciated even when their protective functions are not deployed. These benefits contribute to social resilience, natural carbon sequestration, community health, and quality of life.

Climate crisis, biodiversity crisis

Each year, we’re seeing devastating climate change-related impacts around the world. From polar icecaps melting at a terrifying pace to wildfires in the US, Turkey, and Australia. From flooding in Germany, Pakistan, Nigeria to hurricanes and typhoons in the US and elsewhere. This is world we live in.

A biodiversity crisis is essentially a climate crisis. As we look to the future, we must take note of climate change and biodiversity crises. We will see the impacts on nature, horticulture, and landscapes. Mitigating them means future generations will be able to survive in the public spaces that we enjoy today.