In a series of recent articles, The Economist reveals the alarming impacts of air pollution on the population of the world’s largest urban centers. The article suggested that “air pollution shortens the lives of a city’s inhabitants by 9 to 16 months.” Viewed on a macro scale this claim reveals a staggering effect on human life, equating to 8.7 million years of life lost in London England alone, 8.4 million years lost in New York City, and 11.5 million in Beijing. This estimate is based on a study published in 2015 by King’s College. Whether you take any stock in that claim or not, it is certain that air pollution is having a negative impact on our health and undoubtedly the health of the environment.
Well, that sucks. So now what? Cars, or car fumes, are one of the major culprits contributing to air pollution, however, while the shift to electric automobiles is in motion, (Germany recently revealed legislation mandating the elimination of fossil fuel based cars by 2030,) it will be a gradual process. Dirty coal-fired power generation is also being phased out in many areas, but again, gradually. By the time the “sunshine economy” finally arrives most of us will be old and grey.
In times of trouble many look to the sky. A report by the GSA suggests precisely that, but it is not the divine, but rather the sublime that it points to. The report outlines the benefits of expanding beautiful green space within urban centers using the enormous expanse of underutilized rooftops that can be found in any given city. Green roofs have many benefits including the ability to:
- Recover green space
- Reduce negative impacts of urban development
- Improve Storm Water Management
- Improve water quality
- Conserve energy
- Mitigate urban heat islands
- Increase longevity of roofing membranes
- Improve return on investment over traditional roofing
- Reduce noise and air pollution
- Sequester carbon
- Increase biodiversity by providing wildlife habitat
- Provide space for urban agriculture
- Provide aesthetically pleasing and healthy environments to work and live
Green roofs are 100% renewable, and properly designed require little maintenance, almost no fertilizer or pesticide, and can be markedly less expensive to install in comparison to commonly used stormwater management systems. In short, green roofs are a great idea, but where do you put them? Le’s have a look. Manhattan Island is 22.7 square miles or 59 square kilometers in area. If two-thirds of that area is building footprint this leaves roughly 15 square miles of rooftops. Realistically, let’s assume that 20% of this rooftop space could be readily converted to green space. This works out to about 3 square miles or nearly two and a half times the size of central park. If just 10% of rooftops could be converted we would still be looking at an area equal to or slightly greater than the size of central park.
In an article by Scientific American, it estimates that 1 acre of grassland can sequester up to 0.28 tonne of carbon per year. Assuming that the green roofs installed mimic the properties of efficient natural grassland, if 3 square miles of green roofs were added to New York City, based on this calculation, 560 additional tonnes of carbon would be automatically pulled from the atmosphere per year. In addition, buildings would see a significant drop in energy usage, which would translate into fewer emissions from non-renewable power generation stations. Done properly, green roofs would also reclaim long lost natural habitats within the urban center, attracting wildlife. This addition would also help New York City’s ever worsening flood problem by providing effective storm water management. As an added bonus, residents with a green roof could plant gardens. Who doesn’t love a homegrown tomato? And to top it all off it, adding 3 square miles of green roofs would provide awesome, relaxing, and healthy space for thousands of people to enjoy. A second central park in the sky, not too shabby.