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SCIENCE MATTERS: How much food can cities produce? 

click to enlarge Kent Kallberg via the David Suzuki Foundation
  • Kent Kallberg via the David Suzuki Foundation

Humans are fast becoming city dwellers. According to the United Nations, “The urban population of the world has grown rapidly from 746 million in 1950 to 3.9 billion in 2014.” Sixty-six per cent of us will likely live in urban environments by 2050. The number of mega-cities (more than 10 million inhabitants) is also skyrocketing, from 10 in 1990 to 28 in 2014—home to more than 453 million people—and is expected to grow to 41 by 2030.  

Along with concerns about climate change and the distances much of our food travels from farm to plate, that’s spurred a renewed interest in producing food where people live. Urban agriculture won’t resolve all food production and distribution problems, but it could help take pressure off rural land while providing other advantages. From balcony, backyard, rooftop, indoor and community gardens to city beehives and chicken coops to larger urban farms and farmers’ markets, growing and distributing local food in or near cities is a healthy way to help the environment.  

And it’s much more. As writer and former Vancouver city councillor Peter Ladner (also a David Suzuki Foundation board member) writes in The Urban Food Revolution: Changing the Way We Feed Cities, “When urban agriculture flourishes, our children are healthier and smarter about what they eat, fewer people are hungry, more local jobs are created, local economies are stronger, our neighbourhoods are greener and safer, and our communities are more inclusive.”  

Local and urban agriculture can also help reduce greenhouse gas emissions and recycle nutrient-rich food scraps, plant debris and other “wastes.” Because maintaining lawns for little more than aesthetic value requires lots of water, energy for upkeep and often pesticides and fertilizers, converting them to food gardens makes sense.  

A 2016 study from the US Johns Hopkins Center for a Livable Future found that urban agriculture could “increase social capital, community well-being, and civic engagement with the food system,” as well as enhance food security, provide ecosystem services, improve health and build residents’ skills. Gardening is also therapeutic.

The study found many climate benefits, including reduced emissions from transporting food; carbon sequestration by vegetation and crops; possible reduced energy, resource inputs and waste outputs; and enhanced public interest in protecting green spaces. It also noted some limitations: possible increases in greenhouse gas emissions and water use “if plants are grown in energy- or resource-intensive locations”; less efficiency than conventional agriculture in terms of resource use and transportation emissions; and, depending on practices, pollution from pesticide and fertilizer use. The study found urban agriculture to be positive overall, but concluded support from all levels of government is required to make it viable.  

Urban agriculture isn’t new. During the First and Second World Wars, Canada, the US, the UK, Australia and Germany encouraged “victory gardens” to aid the war effort by reducing pressure on food systems and farms. Gardens and chicken coops appeared in yards, parks, school fields, golf courses, railway edges and vacant lots. Sheep grazed on sports fields and kept grass in check. Peter Ladner notes that, during the Second World War, the U.K. had 1.5 million allotment plots producing 10 percent of the country’s food, including half its fruit and vegetables; and by war’s end, more than 20 million home gardens supplied 40 percent of US domestically consumed produce.  

Granted, there were fewer people and more open spaces then, but it’s still possible to grow a lot of food in urban areas, especially with composting and enriched soil techniques. Ladner writes that Toronto plans to supply 25 percent of its fruit and vegetable production within city limits by 2025, and a study from Michigan State University concluded Detroit could grow 70 percent of its vegetables and 40 percent of its fruit on 570 vacant lots covering 5,000 acres of city land.  

One patch of Detroit land where 12 vacant houses were removed to grow food has supplied almost 200,000 kilograms of produce for 2,000 local families, provided volunteer experience to 8,000 residents and brought the area new investment and increased safety.  

Cities needn’t be wastelands of car-choked roads and pavement. Incorporating food production into ever-expanding urban areas makes cities more liveable and enhances the natural systems that keep us alive and healthy.


Science Matters is a weekly column on issues related to science and the environment from David Suzuki, written with contributions from David Suzuki Foundation senior editor Ian Hanington. Learn more at


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