Urban areas occupy less than 1 per cent of the Earth’s land surface but house more than half of its people. Despite their steel and concrete, crowds and traffic, cities and towns are still ecosystems whose condition profoundly marks the quality of our lives. Functioning urban ecosystems help clean our air and water, cool urban heat islands, and support our well-being by shielding us from hazards and providing opportunities for rest and play. They can also host a surprising amount of biodiversity.
However, through a process of rapid and unplanned urbanization, humans keep on transforming the natural world and created new realities: the UN Decade for Ecosystems Restoration recognizes urban ecosystems as a separate ecosystem type alongside other traditional ones, such as forests, wetlands, and marine ecosystems.
Left unchecked, urbanization has devastating impacts on natural ecosystems, which in turn negatively affect the wellbeing of urban populations. As cities grow, they take space from agricultural and industrial lands that then need to expand into other ecosystems. And as urban administrative boundaries are set ignoring the natural landscape, diverting water streams, deforesting slopes, or paving key infiltration areas, climate change impacts on urban dwellers become more and more dangerous.
The consequences of nature loss in and around cities are already damaging the life-supporting systems of food, water, and air on which we depend. Adopting nature-based solutions at the urban level to protect, conserve and restore these degraded ecosystems, and mainstreaming the landscape scale in urban planning is key to reconnect cities with nature and mitigate the impact of climate change on urban communities.
To make peace with nature and achieve the goals of the UN Decade, we need to build cities in harmony with ecosystems. UNEP seeks to create a new vision of cities that are less carbon intensive, that protect carbon sinks, and incorporate ecosystem-based adaptation in urban planning, acting to protect and restore nature, and support efforts to help governments finance and implement Nature-based Solutions (NbS) in their jurisdictions.
With their convening power, cities can increase and catalyse investment in nature. Cities investing in nature can initiate positive tipping points that can collectively reverse socio-economic impacts of climate change and biodiversity loss, to build sustainable, resilient, healthy urban communities.
Urban NbS can strengthen cities’ resilience to flooding and soil erosion, increase air and water quality, adapt to extreme temperatures, and build healthier communities. NbS actions in cities can increase life expectancy and are also key to improving people’s quality of life.By providing a series of co-benefits, nature-based solutions are both critical and feasible steps that cities can initiate right now to improve local and global wellbeing.
In 2021, in partnership with the G20 Italian Presidency, UNEP developed the Smart, Sustainable and Resilient cities: the Power of Nature-based Solutions report, which outlines the potential of NbS to help build smart, sustainable and resilient cities, drawing from more than a decade of research and experience from G20 countries and beyond.
