The ‘Pernicious Paradox’ of Urban Forestry 

Renata Happle


How do we fundamentally transform the way we live in cities? Globally, nations are grappling with the answer to this question as we stare down the barrel of the largest ecological crisis of our time. Cities, teeming with people and covered in cement, consume over two-thirds of the world’s energy and produce over seventy percent of global CO2 emissions. They are the most at risk, too, with ninety percent of the world’s cities settled on vulnerable coastlines, meaning they would be the first to fall to sea level rise and flooding. The amount  of people flocking to cities has also increased, with sixty percent of the population projected to live in urban areas by 2030. Stefano Boeri, famed architect of the Bosco Verticale, advocates for the integration of trees and plants into cities in order for them “to become the protagonists of a challenge that every day becomes more difficult.” Cities have the opportunity to become a part of a solution for their own problems by using  trees to mitigate carbon emissions as well as reducing pollution, energy consumption, and the urban heat island effect. Having trees and green spaces function as a biogenic municipal utility benefits both the government and the citizens as a long term investment in communities. However, confronting the issue of green space in urban environments straddles a fine line of attempted environmental benefit and mitigating social harm. Green space benefits a neighborhood’s aesthetics, its residents’ physical and mental health, and provides space for wildlife to flourish, water to filter, heat to be absorbed. Alongside that however, greenspaces often bring waves of gentrification, wiping out those who were intended to reap the benefits and pushing them out of their homes. 


Cities, known for their impermeable concrete and masses of people, have a problem coexisting with the nature around them. The Urban Heat Island Effect (UHI) describes a phenomena where urban landscapes are 1.8 to 5.4 degrees Fahrenheit warmer than their surroundings, causing increased energy consumption, elevated emissions of greenhouse gases, and impaired water quality, due to a lack of green permeable surfaces  reflecting heat. Darker surfaces like metal and concrete absorb rather than reflect the heat which warms the surrounding areas. Cities are predicted to only get hotter.  New York City’s surface is more than 70% impermeable, leading to its large UHI. Because of the urban heat island effect, buildings have to work much harder to cool their interiors as they  are being heated from the exterior. The more affordable and feasible option is to retrofit existing buildings with green additions, like green roofs and walls. Buildings consume forty percent of the nations total energy consumption, thirty two percent of that is from heating and cooling, so with the addition of a green roof or wall it would naturally insulate and remove heat through the process of evapotranspiration, in addition to filtering rainwater. The EPA recently conducted a study on how the addition of green roofs and urban forestry reduces the Heat Island Effect, stating: “Green roof temperatures can be 30–40°F lower than those of conventional roofs and can reduce city-wide ambient temperatures by up to 5°F. In addition, green roofs can reduce building energy use by 0.7% compared to conventional roofs, reducing peak electricity demand and leading to an annual savings of $0.23 per square foot of the roof’s surface.”


The face of urban forestry is not the greenest but the ‘shiniest’. Often what comes to mind are the flashy, new  buildings like Bosco Verticale, which are an architectural feat,but come with  inaccessability of price and the emissions of construction. Architect Stefano Boeri is credited with creating “a world symbol uniting biophilia and urbanism” with the two Bosco Verticale towers each boasting 800 trees, 15,000 perennials, and 5,000 shrubs providing the equivalent 30,000 square meters of forest, attempting a movement of  “spontaneous flora and fauna recolonization in the city.” Despite its obvious groundbreaking nature, it is not representative of the entire urban forestry movement as it is almost too  luxurious and uses a large amount of resources to produce and maintain. The materials used to produce said green/forested buildings also contribute to their carbon footprint. Cross laminated timber is emerging in the construction field, outperforming conventional materials like concrete or steel, and comes with a smaller carbon footprint compared to conventional timber. Unlike concrete, which emits one ton of carbon dioxide per cubic meter created, CLT contains sequestered carbon, which is long term carbon absorption. It also has been dubbed ‘the concrete of the future’ due to its high degrees of flexibility and resistance.


Another more efficient option are the benches created by German startup Green City Solutions. The company created a mossy ‘living’ wall flanked by benches on each side, filtering the equivalent amount at 275 trees in 1% of the space. A grove of adult trees, with each on average absorbing 0.022 metric tons of CO2 each year, could absorb 2.2 metric tons. Each CityTree removes 240 metric tons a year, and 250 grams per day due to their use of moss. These benches have a solar powered irrigation system using stored rainwater, making them almost completely self-sufficient. 


Despite the benefits of these green implementations, like community gardens or public parks, they come with a series of social detriments and environmental costs. With their addition, they drive up the price of surrounding real estate contributing to a new phenomenon called ‘green gentrification.’ Communities most in need of green space are further removed from their benefits, driving up existing environmental racism and inequalities in the area, and pushing residents out. New York City has a history of leading movements to ‘revitalize’ and ‘renew’ their neighborhoods, many with lower income and residents of color, however, sociologist Stephen Steinberg states that these discourses of upheaval provided “an ideological façade for the neoliberal war against the poor.” Revitalization and renewal would begin the razing and displacement of low income communities like in the cases of Seward Park, Tompkins Square Park, and Prospect Park. Harlem, however, is the most exemplary case of environmental gentrification with the lowest per capita green space and some of the highest asthma and poverty rates. In response to Mayor Bloomberg’s PlaNYC 2030 goals of implementing 480 ‘pint sized parks’ across the five boroughs to “promote sustainable economic development and community revitalization,” the average price of an apartment ballooned to 93% higher than the previous year’s levels and white households began moving into Harlem at a significantly higher rate.  Urban development has used green space as an arm of capital growth rather than of community growth; “The combination of market forces in urban real estate, institutional and cultural racism, and urban environmental policy can be a powerful tool of urban renewal and urban removal, with the greening’ of urban areas becoming code for the ‘whitening’ of urban areas.” Therefore causing a development domino effect, developing and gentrifying the communities who call ‘revitalized’ neighborhoods home, and therefore green constructions often “exacerbate racial injustices.” Researchers in East Boston concluded: “the reality of multiple injustices occurs precisely because the risks prioritized by socially vulnerable groups (displacement, physical insecurity) are deprioritized in the name of addressing identified climate risks through green infrastructure.” 


The interconnectedness of nature and community intersect in all of these issues: Harlem has the largest percentage of impermeable surfaces of all the boroughs leading to its high UHI and asthma rates. It is quite clear that Harlem, out of any borough, needs green spaces but its residents cannot afford it. Can we green cities without causing gentrification? Returning to the three pillars of sustainability (environment, economy, and equity) an alternative vision forms as ‘just green enough,’ illustrated through the Newtown Creek Alliance in Brooklyn and Queen which aims to clean up the environment while retaining and creating working class jobs. The Newtown Creek Alliance, composed of residents of both boroughs, is cleaning “the worst smelling district in the world” based on explicit demands of those most affected by the contamination while creating green spaces within areas zoned for manufacturing rather than pushing for its rezoning. Now, the Newtown Creek Nature Walk serves as an example to follow for community led advocacy and development. 


Urban forestry finds itself facing a “pernicious paradox” where communities must choose between rejecting environmental amenities in order to resist the gentrification that is bound to follow.  Cities find themselves facing the same dilemma, where the need for climate mitigation is as dire as the need for affordable housing. With community driven initiatives led by their individualized needs, cities can be a tool in fighting climate change without causing harm to its residents.