If you’ve spent any time on the roof, you know that it’s not particularly pleasant up there – hot in the summer, and bitterly cold and windy in the winter. However, put some solar panels there, and the calculus changes: shaded from wind and excessive sunlight, Crops can multiplya technology known as rooftop cell farming. Because these devices provide shade, evaporation is reduced, resulting in significant water savings. Plus, all this greenery insulates the upper floor, reducing energy costs.
Urban areas, long at odds with each other, are embracing elements of the rural world as they try to produce more of their own food, in community gardens on the ground and agricultural farms above. In an increasingly chaotic climate, urban agriculture can improve food security, generate clean electricity, lower local temperatures, and provide refuges for pollinators. and – Improving the mental and physical health of city residentsamong other benefits.
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With relatively cheap investments in food production – especially if there is empty space – cities can solve a range of problems at once. For example, Quezon City in the Philippines has converted unused land into more than 300 gardens and 10 farms, and in the process trained more than 4,000 urban farmers. Detroit spotted Thousands of gardens and farms. In the Big Apple, the nonprofit Project petals It transforms vacant land in low-resource neighborhoods into oases. “There are some places in New York City where there is not 5 miles of green space,” said Alicia White, executive director and founder of the group. “We know that green spaces help reduce stress. We know that they help combat loneliness, and we know at this point that they help improve respiratory and heart health.”
This makes these community spaces a particularly powerful climate solution, because it has become much more difficult for people to stay healthy in cities due to the urban heat island effect, where the built environment absorbs the sun’s energy and releases it throughout the night. With baking day after day during long heat waves, the human body cannot get rest, which is a particularly dangerous scenario for the elderly. But patches of green reduce temperatures by releasing water vapor—essentially sweating through the neighborhood—and providing shade. Meanwhile, as climate change makes rainfall more extreme, urban parks help absorb the deluge, reducing the risk of flooding.
Oddly enough, while the furnace-like effect is risky for people, it can benefit city farms. On rooftops, scientists have found that some crops, like leafy greens, thrive under the shade of solar panels, but others — especially warm-season crops like zucchini and watermelon — grow beautifully in harsh full-sun conditions. “Most of our high-value crops benefit from the urban heat island effect, because it lengthens their growing season,” said horticulturist Jennifer Bousselot, who studies rooftop farming at Colorado State University. “So growing food in the city actually makes perfect sense.” “This summer we had an option the size of baseball bats, and it was a perfect fit for the green roof.”
Kevin Samuelson, CSU Spear
That’s not all that’s thriving there. Bousselot and her team also grow three local crops: corn, beans and squash. Beans climb corn stalks—and microbes in their roots fix nitrogen, enriching the soil—while squash leaves shade the soil and reduce evaporation, saving water. In addition, they found that saffron – an expensive and difficult spice to harvest – tolerates the shade of rooftop solar panels. Water emerging from the soil also cools the panels, increasing their efficiency. “We create a microclimate that is very similar to a greenhouse, which is one of the best conditions for most of our food crops to grow,” Bousselot said. “But it’s not a system that needs to be heated, cooled or vented, like a greenhouse does.”
Farmers may use the harsh surface conditions to another advantage. Plants not shaded by solar panels produce “secondary metabolites” in response to the heat, wind, and constant sunlight that can stress them. These are often antioxidants, which a grower might be able to extract from a medicinal plant like chamomile – at least in theory. “We’re kind of exploring the scope of what’s possible out there, and using those unique environments to come up with crops that will hopefully be more valuable to the producer,” Bousselot said.
On the ground in New York City, Project Petals has seen a similar boom. While agricultural areas grow vast fields and orchards of monocrops, such as grains or fruit trees, an urban farm can pack a range of different foods into a narrow space. “If you can grow it in rural areas, you can grow it in the city, too,” White said. “We grew pumpkins, peas, and lemongrass. In our gardens, I saw just about everything.”
This type of diversification means an abundance of nutritious foods flows into the community. (Many different species also provide different types of flowers for pollinators—the more pollinators, the better the area’s native crops and plants can reproduce, creating a virtuous cycle.) This is invaluable because in the United States, access to proper nutrition is extremely unequal: in Mississippi, for example, 30 percent of people They live in low-income areas where they have access to only good food, compared to 4 percent in New York. This leads to “silent hunger,” where people get enough calories — often from ultra-processed foods bought from convenience stores — but not enough nutrients.
Underserved neighborhoods need better access to supermarkets, of course, but rooftop gardens and community gardens can provide fresh food and help educate people about improving their diet. “It’s not just about growing vegetables in the city, but actually it’s also a way to change habits,” says Nicolas Galli, a postdoctoral researcher who studies urban agriculture at the Politecnico di Milano.
In a He studies Last month, Galli published in the journal Earth’s Future a model of what such change could look like on a large scale in São Paulo, Brazil. In a theoretical scenario in which the city converted its potential free space — about 14 square miles — into parks and farms, every two acres of food production could provide a healthy livelihood for more than 600 people. Although the scenario isn’t particularly realistic, given the scale of change needed, “it’s interesting to think that if we used almost all of the areas we have, we could provide missing fruits and vegetables for about 13 to 21 percent of the city’s population,” Galli said. “Every square meter you make can have a function, and can be useful to increase someone’s access to healthy food.”
Without urgent action here, silent hunger will get worse as urban populations around the world explode: by 2050, 70 percent of humans He will live in cities. Urban farms can go a long way toward helping feed all these people, and they can actually benefit from the movement of rural farmers to big cities. “They’re able to take that to community members like me from New York City, who might not have had the experience, and help them find their way in learning how to garden and learning how to grow their own food,” White said.
Whether on the roof of a building or between residential buildings, the urban garden is a simple yet uniquely powerful tool for solving a wide range of environmental and human health problems. “They serve as spaces where people can grow, where they can learn, where they can help fight climate change,” White said. “It’s very good to see that people are starting to realize the fact that park space and green space can have a bigger impact than just impacting this community in general.”