I’ve discussed how individuals living in urban areas can take action to live sustainably, now I will talk about how cities take steps towards improving overall sustainability through urban green spaces. The EPA characterizes green spaces as land that is partly or completely covered with grass, trees, shrubs, or other vegetation. Examples of urban green spaces include parks, community gardens, storm water ponds, lakes, playing fields, and public plazas. When analyzing anything in light of sustainability, it is crucial to look at the topic as a whole. In relation to urban sustainability, urban green spaces provide a large variety of benefits for each leg of the sustainability stool; social, environmental, and economic. These pillars are also known as The Three P’s of Sustainability; planet, profit, people I first learned about this concept as a “stool” because equal balance among each “leg” is needed to hold the stool up properly, and if one “leg” is off balance then true sustainability is not achieved.

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I will look at each leg of the stool to thoroughly explain how urban green spaces attribute to a balanced sustainable society.

In my previous blog posts, I have specified how urbanization threatens the environmental health of a city. Fortunately, parks protect the quality of the urban environment in a variety of ways. San Francisco’s Urban Forest Plan says green space slows climate change and estimates that all of the city’s trees store 196,000 tons of carbon annually, divert 516,468,000 gallons of water from the sewer system, and the total environmental benefits of the trees is $9.4 million. The urban heat island effect is a significant health risk, as more people die in summer hot spells than all other weather events in the U.S combined. Green spaces reduce the urban heat island effect and help avoid this health risk. According to the University of Washington’s Center for Urban Horticulture, a mature tree canopy “reduces air temperature by about five to ten degrees.” Also, trees in parks remove pollutants from the atmosphere and improve air quality. Other environmental benefits include maintained groundwater levels, provided wildlife habitat, and reduced noise pollution.

Urban green spaces add a substantial amount of economic value to their surrounding community. Parks increase property values and potential home buyers seek out neighborhoods with parks.

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This table shows the increased property values associated with residential property surrounding parks in San Francisco. According to a study completed by Ernst and Young, New York’s Bryant Park was redeveloped in 1992, and by 2002, asking rents for commercial office space rose between 115 and 225%. Comparatively, asking rents in surrounding submarkets only rose between 41 and 73%. Parks attract tourists and businesses, increasing the city’s revenue. Overall, urban green spaces are good for bringing in money from outside spenders and for increasing property values, therefore expanding a city’s economic value.

Lastly, to balance the sustainability stool, city parks improve social benefits within communities. San Francisco’s Urban Forest Plan associates social park value with stronger communities, improved physical health, reduced violence and crime, and increased bicyclist and pedestrian safety. In relation to improved physical health, health studies have shown that contact with nature offers a range of medical benefits including: lower blood pressure and cholesterol levels, enhanced survival after a heart attack, more rapid recovery after surgery, and lower self-reported stress. Also, a telephone survey conducted for the American Public Health Association found that 75% of adults believe parks and recreation must play an important role in addressing America’s obesity crisis.

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This image visually represents some physical health benefits attributed to parks in Portland, Oregon. Parks are important for building relationships among community members and connecting urban dwellers to natural environments.

It is important we take time to appreciate all the benefits urban parks bring to cities. Now that I’ve described the benefits of urban green space in terms of each leg of the sustainability stool, it easy to see how complicated it is to achieve full sustainability. The stool can be easily unbalanced, and this requires much effort from cities to maintain equal representation of each leg. Luckily city officials can use urban green space to enhance any missing part of the stool and direct society towards long-term sustainability.