Could urban farming feed the world?

In 1982, artist Agnes Denes planted 2.2 acres of wheat on waste ground in New York’s Battery Park, near the recently completed World Trade Center. The towers soared over a golden field, as if dropped into Andrew Wyeth’s bucolic painting Christina’s World. Denes’s Wheatfield: A Confrontation* *was a challenge to what she called a “powerful paradox”: the absurdity of hunger in a wealthy world.

The global population in 1982 was 4.6 billion. By 2050, it will be more than double that, and the prospect of feeding everyone looks uncertain. Food insecurity already affects 2.3 billion people. Covid-19 and extreme weather have revealed the fragility of the food system. Denes was called a prophet for drawing attention to ecological breakdown decades before widespread public awareness. But perhaps she was prophetic, too, in foreseeing how we would feed ourselves. By 2050, more than two-thirds of us will live in cities. Could urban farming feed 10 billion?

Urban agriculture (UA) covers everything from hi-tech approaches such as vertical farming and soil-free processes such as hydroponics, aeroponics and aquaponics, to guerrilla gardening on the urban fringe. It’s not a new idea: victory gardens supplemented rationing during both world wars. In the 1970s and 80s, the “green guerrilla” movement farmed hundreds of vacant lots across Manhattan. In the 1990s, the UN recognised urban agriculture as crucial to development. During the Syrian civil war, citizens of besieged eastern Ghouta farmed mushrooms in their basements.

The pandemic spurred a brief urban farming boom, with £4.5bn invested in vertical farming startups in 2021. Many folded as the world emerged from lockdown, suggesting the UA bubble had burst. But like the most tenacious plants, this idea won’t go away. In January, the Scottish government opened a new £1.8m Vertical Farming Innovation Centre. Farms have sprouted in Brooklyn shipping containers, subterranean car parks in Paris, second world war bomb shelters beneath London and on rooftops from Hong Kong to Singapore. Already, UA produces between 5% and 10% of the world’s legumes, vegetables and tubers.

Farming the city would improve diets in the global north and provide the Gglobal south with more calories. One 2025 study suggests that UA could help meet the UN’s 2030 sustainable development goals on hunger, sustainable cities and responsible consumption. It would also cut vulnerable supply chains and the carbon associated with transportation and packaging to keep food fresh. A 2013 study found that a kilo of food grown in London produced on average 2.23kg less CO2 than conventional agriculture.

Soil-free growing eases pressure on stressed soils and overburdened waterways. The World Economic Forum estimates that vertical farming uses up to 98% less water than regular farming. Rainwater can be harvested from rooftops and urban wastewater recycled, even human waste-filled “black water”, if treated to remove harmful bacteria, due to its nitrogen and phosphorus content. As these are closed loop systems, no pollution makes its way into rivers.

Green rooftops would cool buildings, reducing the urban heat island effect. Moreover, food sovereignty releases people from dependence on industrial agriculture, especially in under-resourced areas. Growing is a deeply human thing to do. Becoming producers as well as consumers would empower communities and enrich individuals.

Before the picture becomes too utopian, it’s important to recognise that UA is not a straightforward solution. Open-air farming near roads can draw pollutants into the food chain, whereas indoor growing is highly energy-intensive. A vertical farm occupying a 30-storey building with a 5 acre (2 hectare) footprint could produce a yield equivalent to 2,400 acres (971 hectares), year-round, regardless of climate or weather, but the energy needs, scaled up to planetary levels, are unsustainable.

A patchwork approach would be best. Energy-intensive, hydroponic indoor farms suit the Gulf states, where 85% of food is imported, and where there is limited fresh water but access to abundant renewable energy. Elsewhere, low-impact farming of the urban fringe, while less productive, would be more suitable. As reported in this paper, “nature connectedness” – a measure of the closeness of an individual’s relationship with other species and the wild world – has declined by 60% since 1800. A holistic approach to growing known as agroecology could help here. Defined by principles rather than practices – including being responsive to the local environment; building healthy soils; protecting biodiversity; and minimising external inputs – it could transform street corners and waste grounds into bread baskets.

In Edinburgh, not a mile from my house, Lauriston Farm is an agroecology cooperative converting 100 acres (40 hectares) of former sheep pasture on the edge of the city into a dynamic mix of market garden, community allotments, agroforestry (where crops are planted alongside trees to improve soils and yields) and orchards, as well as restored wetland and meadow. Like Denes’s Wheatfield, crops grow in sight of tall buildings (flats rather than skyscrapers). It’s one of the most quietly radical spaces in the city.

Lauriston Farm can’t feed the city, but small acts combined can achieve remarkably big results. Globally, small farmers produce between a third and a half of the world’s calories, without recourse to the damaging, yield-boosting practices of industrialised agriculture. Agroecology could alter not just where our food comes from, but our relationship with the natural world. Its principles should be integrated into municipal and economic planning, changing how the city looks, and mixing green and gold among the grey. But gaps in national and local policy make this difficult. Edge lands should be mapped and disused land made available, along with investment and training, to help communities start growing.

UA alone won’t feed 10 billion people. But neither can we afford to ignore it. We need to prevent food wastage, preserve soils, halt pollution, arrest climate breakdown and protect biodiversity, especially pollinators. “My garden’s boundaries are the horizon,” wrote Derek Jarman in Modern Nature. Every change, however small, expands the horizon of what we think is possible.

*David Farrier is the author of Nature’s Genius: Evolution’s Lessons for a Changing Planet (Canongate).

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