Rooftop gardens. Seedlings sprouting on windowsills. The clucking of chickens in a metropolitan backyard. These and more are small harbingers of the expansion of urban agriculture around the world.
More than half of the world’s population lives in cities, a figure that the United Nations expects to increase to 67% by 2050—yet urbanized land makes up just 1% of the Earth’s surface. Because of this, urban planners are working to make cities more resilient, habitable, and adaptable to change.
In a new paper, Clinton et al. have developed a framework to estimate the environmental benefits of urban agriculture on a global scale—current and future. The team envisions a scenario in which over the next few decades, cities around the world adopt intensive efforts to expand urban agriculture.
Using Google Earth Engine, a free platform for processing global satellite data, the researchers analyzed data sets on population, urban landscapes, meteorology, terrain, and food and agriculture. They developed national estimates for the entire globe of ecosystem services provided by urban agriculture, finding that existing vegetation in urban areas provides the equivalent of about $33 billion each year.
In more specific terms, the team estimates that urban agriculture, if deployed across all available vacant land, rooftops, and building façades, could produce 100–180 million tons of food, save about 14–15 billion kilowatt hours of energy, sequester 100,000–170,000 tons of nitrogen, and offset roughly 2 trillion cubic feet of storm runoff each year.
Projected out, the researchers estimate that dramatically increasing urban agriculture efforts around the globe has the potential to positively influence food production, nitrogen fixation, energy savings, pollination, climate regulation, soil formation, and the biological control of pests, services that are worth, as a whole, as much as $160 billion.
The team’s findings show that urban agriculture has the ability to improve food security and ecosystem health on a global scale. Although its impacts vary from country to country, the results are promising. This study is a thorough look at the importance of urban agriculture, especially in the face of global climate change and unsustainable urban development practices around the world. (Earth’s Future, https://doi.org/10.1002/2017EF000536, 2018)
—Sarah Witman, Freelance Writer