The carbon footprint of fruits and vegetables grown in urban gardens in Europe and the United States is, on average, six times greater than the same produce grown on traditional farms, researchers say.
Farmers and gardeners from 73 urban farming sites in France, Germany, Poland, the United Kingdom and the United States will participate as citizen scientists in a study led by scientists at the University of Michigan, announced Monday. natural city. This study is the largest ever conducted to compare emissions from urban and conventional agriculture.
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The researchers tracked greenhouse gas emissions from agricultural infrastructure, supplies, and irrigation water through daily diaries created during the 2019 season. Researchers found that, on average, food grown in urban gardens emits 0.42 kilograms (0.9 pounds) of carbon equivalent per serving, compared to 0.07 carbon equivalents per serving for food grown on conventional farms. It was discovered that they emit the equivalent of a kilogram of carbon dioxide.
However, some crops were found to be less carbon-intensive when grown in cities than on traditional farms. Urban tomatoes often outperform conventional tomatoes, primarily due to the energy intensity of commercial greenhouses. Perishable traditional vegetables like asparagus are often transported by plane, but their carbon footprint is equal to or higher than the same crops grown in cities.
Approximately 20% to 30% of the world's urban dwellers engage in some form of urban agriculture, most of which takes place outdoors on soil. Growing food in cities has benefits, such as mitigating the high temperatures caused by heat-trapping asphalt and concrete, known as the urban heat island effect. It also provides important social and health benefits for those involved, including improved mental health, improved dietary habits and strengthened local social networks.
Research on the crops that urban farmers choose to grow shows that motivations for choosing vegetables vary widely and are driven by priorities such as a balanced diet and cultural preferences. People may choose to grow food that is less available in the city where they live. However, the most common motivation among the people the scientists surveyed for this study was environmental sustainability.
“Urban agriculture offers a range of social, nutritional, and place-based environmental benefits that make it attractive for future sustainable cities,” Jason Hawes, co-lead author of the paper, said in a statement. It has become a distinctive feature.” “Urban farmers can reduce their climate impact by making changes to site design and management, as well as growing crops that are typically grown in greenhouses or airlifted.”
The authors found that switching crops is not the only way to make urban agriculture more climate-friendly. “Most of the climate impacts of urban farms are caused by the materials used to construct them, the infrastructure,” said co-lead author Benjamin Goldstein. “These farms typically only operate for a few years or 10 years, so the greenhouse gases used to produce these materials are not effectively utilized.”
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Extending the life of materials and structures such as raised beds, composting containers, and sheds can help reduce the footprint of urban gardens. The researchers also suggest reusing urban waste, such as construction debris and demolition, in building structures, and using rainwater and recycled water for irrigation.
The researchers concluded that the social benefits of urban farming are so high that urban farming still outperforms conventional agriculture when carbon and environmental impacts are considered together.
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