Home to more than half of the world’s population, our growing cities are responsible for a disproportionately large ecological footprint. This presents a unique threat to the natural ecosystems cities depend on for climate regulation, protection against hazards, energy provision, as well as the health and wellbeing of urban residents.
Better protection and enhancement of urban biodiversity can dramatically increase the resilience of our cities to current stresses and future risks. It is our task to critically examine how.
Urban biodiversity supports local economies within cities and, in some cases, is critical to national capital.
In Beijing, the water stored in one hectare of urban green area reduces water runoff and stores enough water to create an economic benefit equivalent to three quarters of the maintenance costs of the city’s green spaces. In Lanzhou, China, a 2,789 hectare urban forest area provides climate regulation—through cooling and evapotranspiration—that is valued at $14 million USD annually.
In New York, the implementation of a forest protection strategy in the water catchment area of the city was estimated to be seven times cheaper than building and operating a water treatment plant.
Across the United States, city parks increase the value of nearby residential properties by an average of 5 percent—exceptional parks can provide up to a 15 percent increase.
Functioning urban ecosystems significantly enhance human health and well-being.
We depend on ecosystems to meet our basic needs of food, water, clean air, shelter, and relative climatic constancy. Natural ecosystems have a significant role in improving human health, reducing stress, and reducing allergy prevalence. Across cities, children who live in neighborhoods with more trees tend to have lower incidence of asthma. Mere visual contact with vegetation has been shown to improve health, reduce postoperative recovery times, increase employee satisfaction, and reduce stress.
In Sacramento (US), city residents who exercise in parks have been found to have lower medical costs.
Increasing the biodiversity of food systems enhances food and nutrition security.
The present and growing threat of climate change greatly increases the importance of food security and resilience of agricultural systems. Urban agriculture can contribute to soil conversation, urban hydrology, and urban biodiversity.
In Nicaragua, maintaining trees in fields provides medicinal products, fuel-wood, fencing material, and water regulation services.
What can cities do?
Cities can help nations meet national targets for biodiversity in a number of critical ways.
Given the increasing synergy between climate protection and biodiversity, it will be critical for cities to support conservation and restoration of ecosystems, which are essential to achieving the overall goals of key frameworks, such as the United Nations Convention on Biological Diversity and the UN Framework Convention on Climate Change. Cities can contribute to the implementation of the UN Strategic Plan for Biodiversity and Plan of Action, and key areas of the UN Sustainable Development Goals.
They can inspire others by leading and acting on their challenges locally. Increasing collaboration, as the Chief Resilience Officers participating in this week’s 100 Resilient Cities Network Exchange Program in Melbourne, Australia, have done, can unlock new partnerships and collaborations. Working together, cities can find new, and scale up existing projects, programs, and initiatives. This is an important time for cities to take action – the planet, its people, and their well-being depend on it.