Urban Rewilding: Greening Our Cities
As heatwaves and extreme weather events become increasingly common across the world, the urgency to green our cities has never been more pressing. Governments and local authorities are stepping up efforts, recognizing that the future of urban living depends on sustainable practices. Implementing innovative software solutions like Ecoteka can transform our urban landscapes by creating vital cooling islands and optimizing water management.
Combating Urban Heat Islands
What is an Urban Heat Island?
An urban heat island (UHI) is an area within a city where temperatures are significantly higher than surrounding rural areas. Various factors contribute to UHIs, including urban density, city size, human activities, building materials, vegetation density, and geographical features. These factors can be addressed to varying degrees to mitigate the UHI effect.
On a building scale, for example, dark-colored exterior materials absorb and re-radiate heat, exacerbating the UHI effect. Air conditioners also contribute, consuming energy and releasing heat into the immediate surroundings.
To combat UHIs, cities must be redesigned to promote cooling islands.
Identifying Heat and Cool Islands to Redesign Cities
Mapping, analyzing, and characterizing existing heat and cool islands is the first step toward mitigating UHIs. Identifying permeable and impermeable surfaces, as well as low and high vegetation, is crucial. Municipalities should develop multi-year plans to reduce heat islands, create cooling islands, increase greenery, and make public and private spaces more permeable. A cooling island is not just a park; it can be a small area with a mature tree providing shade and a bench for rest, offering a respite from the heat. The temperature difference: There is an 8 to 10°C difference between urban heat islands and urban cool islands.
Trees: Natural Air Conditioners
Trees provide shade, acting as natural air conditioners. Shaded ground can be 25°C cooler than sunlit ground. Besides offering shade and cooling, trees absorb carbon dioxide, playing a vital role in combating climate change. Urban nature, tree presence, and rewilding are crucial for future environmental sustainability.
Natural surfaces in cities have numerous benefits, including dissipating heat through evaporation (soil) and transpiration (plants), or evapotranspiration when both occur together.
Managing urban tree heritage is no easy task. The teams at Natural Solutions aim to make ecoTeka the open-source platform for inventorying, managing, and reinventing urban ecosystems. Several applications are in development, including an AI-based tree inventory tool, a tree heritage management tool for ongoing interventions, and a decision support tool for urban ecological corridors. Issues like soil permeability, nature accessibility, and plant selection engage these teams.
Evapotranspiration: Cooling Urban Air
The process is simple: roots absorb water from the soil, which is transported to the leaves where it evaporates. This evaporation cools the air, which then descends from the leaves to the ground, acting as an efficient urban air conditioner.
This underscores the importance of preserving, caring for, and developing urban trees and vegetation. Green roofs, walls, and permeable surfaces also effectively combat UHIs by reducing the amount of heat absorbed by city materials.
The Role of Water
Urban rewilding in the current context is essential. However, transforming heat islands into cool islands and increasing urban greenery requires water—a scarce and precious resource, especially during heatwaves with frequent water use restrictions.
For example, in Marseille, France, a prefectural decree (No. 85-2022) on May 20 declared a drought crisis in the Huveaune Aval basin, affecting several districts. This decree intensified water use restrictions. Balancing water conservation and maintaining cooling islands, which require water to thrive, is a critical challenge.
By 2050, 8 billion people will live in cities. By greening our cities, we can mitigate the urban heat island effect, improve air quality, and enhance the overall well-being of residents. With urban populations growing rapidly, integrating nature into our urban planning is essential for a resilient and sustainable future. Ecoteka's tools for inventorying, managing, and reinventing urban ecosystems provide the data-driven insights needed to make impactful changes.
Take action now to embrace urban rewilding and sustainable water management. Together, we can create greener, cooler, and more livable cities for generations to come.