Urban agriculture is expected to be an important feature of 21st century sustainability and can have many benefits for communities and cities, including providing fresh produce in neighborhoods with few other options.
Among those benefits, growing food in backyards, community gardens or urban farms can shrink the distance fruits and vegetables have to travel between producers and consumers – what’s known as the “food mile” problem. With transportation’s greenhouse gas emissions eliminated, it’s a small leap to assume that urban agriculture is a simple climate solution.
But is urban agriculture really as climate-friendly as many people think?
Ourteam ofresearchers partnered with individual gardeners, community garden volunteers and urban farm managers at 73 sites across five countries in North America and Europe to test this assumption.
We found that urban agriculture, while it has many community benefits, isn’t always better for the climate than conventional agriculture over the life cycle, even with transportation factored in. In fact, on average, the urban agriculture sites we studied were six times more carbon intensive per serving of fruit or vegetables than conventional farming.
However, we also found several practices that stood out for how effectively they can make fruits and vegetables grown in cities more climate-friendly.
What makes urban ag more carbon-intensive?
Most research on urban agriculture has focused on a single type of urban farming, often high-tech projects, such as aquaponic tanks, rooftop greenhouses or vertical farms. Electricity consumption often means the food grown in these high-tech environments has a big carbon footprint.
We looked instead at the life cycle emissions of more common low-tech urban agriculture – the kind found in urban backyards, vacant lots and urban farms.
Our study, published Jan. 22, 2024, modeled carbon emissions from farming activities like watering and fertilizing crops and from building and maintaining the farms. Surprisingly, from a life cycle emissions perspective, the most common source at these sites turned out to be infrastructure. From raised beds to sheds and concrete pathways, this gardening infrastructure means more carbon emissions per serving of produce than the average wide-open fields on conventional farms.
However, among the 73 sites in cities including New York, London and Paris, 17 had lower emissions than conventional farms. By exploring what set these sites apart, we identified some best practices for shrinking the carbon footprint of urban food production.
1) Make use of recycled materials, including food waste and water
Using old building materials for constructing farm infrastructure, such as raised beds, can cut out the climate impacts of new lumber, cement and glass, among other materials. We found that upcycling building materials could cut a site’s emissions 50% or more.
On average, our sites used compost to replace 95% of synthetic nutrients. Using food waste as compost can avoid both the methane emissions from food scraps buried in landfills and the need for synthetic fertilizers made from fossil fuels. We found that careful compost management could cut greenhouse gas emissions by nearly 40%.
Capturing rainwater or using greywater from shower drains or sinks can reduce the need for pumping water, water treatment and water distribution. Yet we found that few sites used those techniques for most of their water.
2) Grow crops that are carbon-intensive when grown by conventional methods
Tomatoes are a great example of crops that can cut emissions when grown with low-tech urban agriculture. Commercially, they are often grown in large-scale greenhouses that can be particularly energy-intensive. Asparagus and other produce that must be transported by airplane because they spoil quickly are another example with a large carbon footprint.
By growing these crops instead of buying them in stores, low-tech urban growers can reduce their net carbon impact.
3) Keep urban gardens going long term
Cities are constantly changing, and community gardens can be vulnerable to development pressures. But if urban agriculture sites can remain in place for many years, they can avoid the need for new infrastructure and keep providing other benefits to their communities.
The practice of growing food in cities is expected to continue expanding in the coming years, and many cities are looking to it as a key tool for climate adaptation and environmental justice.
We believe that with careful site design and improved land use policy, urban farmers and gardeners can boost their benefit both to people nearby and the planet as a whole.
“Urban agriculture practitioners can reduce their climate impacts by cultivating crops that are typically greenhouse-grown or air-freighted, in addition to making changes in site design and management.” Switching crops is not the only way to make urban farming more climate-friendly, the authors found.
While urban agriculture offers a number of benefits to the environment, including increased biodiversity, pollinator habitats, and nutrient-rich soils through compost production, these operations require mindful resource management throughout the food production cycle to prevent undue stresses on urban services, ...
Urban farming is a productive and relaxing activity, connecting people to their natural environment all while growing fresh, healthy food. There is nothing quite like harvesting lettuce from your own garden to prepare a simple dinner salad or picking blueberries for a homemade fruit cobbler.
Home and community gardeners typically grow food for their own consumption, donation, or limited nonprofit sales. Community gardens typically engage a number of stakeholders. Urban farms operate on a larger scale than community gardens, grow produce for sale, and often require a business license to operate.
Fortunately, our farm and food system can be an important part of the solution, both by reducing emissions at every stage of the food production and distribution process, and by building agroecosystems that can sequester (store) more carbon.
Urban environments can be more challenging for farming due to factors such as limited space, a lack of soil, and exposure to pollution. In addition, urban farming can be more expensive due to the high cost of land and other resources.
Urban farms can provide education about climate change, food security, biodiversity, pollinators, and nutrition to the community. Urban agriculture can increase food access and green spaces in parts of the city that are historically disadvantaged.
Urban agriculture is helping poor people cope with food scarcity and hunger. Growing crops or raising livestock in backyards or on undeveloped plots of land improves food sources and offers many urban poor a viable income.
Traditionally, it has been assumed that cultivating food leads to a loss of biodiversity and negative impacts on an ecosystem. A new study defies this assumption, showing that community gardens and urban farms positively affect biodiversity, local ecosystems and the well-being of humans that work in them.
Decreasing pollution and cleaning air. Filtering stormwater and keeping waterways cleaner. Remaking space for birds to eat, rest and nest. Making space for other displaced animals and organisms, from plants to soil microbes to squirrels (because who doesn't love a squirrel?)
When done correctly, even the smallest backyard plot can produce copious amounts of fruits and vegetables and possibly even a significant saving to the grocery budget. However, it takes time and patience, and a small outlay of money to buy seeds, and tools, if you need them.
Urban community gardens are especially susceptible to problems with sunscald and radiant heat because many are constructed in areas littered with plenty of concrete, pavement, and large structures.
One of the most touted benefits of urban farming is a reduction in food miles, which globally account for three billion tonnes of carbon emissions (nearly 20 per cent of all food-system emissions) annually. However, urban-grown crops aren't automatically a more environmentally friendly option.
Community gardens, rooftop farms, hydroponic, aeroponic and aquaponic facilities, and vertical production, are all examples of urban agriculture. Tribal communities and small towns may also be included.
Contrary to traditional farming, urban farming is the agriculture of food in urban areas that is small space friendly, uses fewer water resources, fewer food miles, more sustainable packaging, and emits less GHG.
Implementing practices like conservation tillage, crop rotation and cover cropping helps sequester carbon, improve soil health and reduce water usage. Additionally, sustainable farming practices contribute to biodiversity conservation, which is vital for maintaining ecosystem resilience in the face of climate change.
At the same time, cities are a key contributor to climate change, as urban activities are major sources of greenhouse gas emissions. Estimates suggest that urban areas are responsible for 70 percent of global CO2 emissions, with transport and buildings being among the largest contributors (IPCC, 2022).
Possible directions for development include actions at varying stages and scales, from optimizing green spaces for urban heat control to employing local and innovative building materials to minimize the carbon footprint or passing laws that help create more sustainable urban and natural environments.
Introduction: My name is Carlyn Walter, I am a lively, glamorous, healthy, clean, powerful, calm, combative person who loves writing and wants to share my knowledge and understanding with you.
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