The Landscape Professional's Role in Mitigating the Urban Heat Island Effect

The Landscape Professional's Role in Mitigating the Urban Heat Island Effect

By Charlie Sandberg
Posted in Outdoor Landscaping
On October 18, 2019

What is the Urban Heat Island Effect?

Let’s start out by visualizing an experiment. Imagine a handful of fresh, green leaves picked off an Oak tree.  Right next to this handful of fresh leaves is a concrete block. Now imagine a heat lamp, directed at both the fresh leaves and the concrete block, shining down for five minutes.  Turn the imaginary lamp off and wait two minutes; which is warmer, the leaves or the concrete block? Concrete absorbs heat and releases slowly, while leaves help to reflect light and disperse heat.

Picture this experiment, but on a much grander scale – specifically New York City.  As majestic as the tall buildings and ornate architecture are, they have had effects on their immediate surrounding environment.  The lack of green space and the steel and pavement, mixed with carbon emitting vehicles and buildings, contributing to the urban heat island.  The sun beating down on heat absorbing materials, such as dark pavement, increases the air temperature as much as 20 degrees or more.

A satellite image from Nasa shows the surface temperatures in New York City on August 14, 2002 at 10:30am.  According to historical data from Weather Underground, the actual high temperature of the day was 88°.  This is a prime example of the heat absorbing concrete raising the temperatures to much higher levels.

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Why Should You Be Concerned?

The understanding that climate change increases extreme weather conditions is accepted by most scientists around the world.  This extreme weather not only references hurricanes and drought, but extreme heat as well. According to the New York State Department of Environmental Conservation, the average annual temperature has risen 2.4° since 1970, and winter temperatures have increased 4.4°.  With the average temperatures rising, risk of heat related illness and deaths increase.  According to the Centers for Disease Control and Prevention, more than 600 people are killed annually due to heat related illness. Living or working in an urban environment such as New York City increases the risk of heat related illness due to the urban heat island effect.

How Vegetation Helps Mitigate the Urban Heat Island Effect?

All plants, both small and large, help reduce storm water runoff, reduce energy consumption needs, improve air quality and help to reduce the surrounding temperature.  A 2005 study published in the Journal of Forestry set out to find the net benefits in dollar value of the trees planted in 5 U.S. cities.  The authors found that for every dollar of investment spent on urban forestry projects, the returns ranged from $1.37 to $3.09.  Trees and vegetation, including green roofs and walls, help to reduce the energy needs of structures. In New York City, buildings are the largest contributor of greenhouse gasses released into the atmosphere.  Planting vegetation such as green roofs and walls, courtyards and street trees reduce the buildings energy needs, which in turn will reduce GHG emissions.  Lower GHG emissions equates to mitigating the urban heat island effect along with many other economic and social benefits. In addition to the economic benefits vegetation offers, each plant can help to reduce the local temperature by 2-9° through shading and evapotranspiration.   

How John Mini Distinctive Landscapes Can Help?

New York City has done an excellent job at reducing GHG emissions and planting trees and vegetation.  GHG emissions alone have fallen 15%  since 2005, despite a booming economy and population growth.  On public lands, there are 694,249 mapped trees comprising of 234 different species. These trees yield tremendous environmental and economic benefits, including 667,590,884 kWh of energy conserved.  The total gross economic benefit of New York City’s trees is approximately $109,842,256.23 and will continue to rise as we plant more trees, shrubs and flowers.  New York City can’t achieve these results on its own, and that’s where John Mini Distinctive Landscapes steps in.  

John Mini Distinctive Landscapes is not in the landscape business, but the beautification, sustainability and climate change mitigation business.  Halfway through the 2018-2019 season, JMDL planted 125,652 plants; each of which had a positive effect on its surrounding environment. JMDL continues to strive for the preservation of our home city, one plant at a time. Through the construction of new green roofs and walls, planting trees in courtyards, parks and streets, JMDL continues to play its part in mitigating the urban heat island effect.

The true impact on the social and economic well-being of New York City is difficult to measure, but the evidence clearly shows the importance of green space in a city filled with steel and concrete.  If one plant can reduce the surrounding temperatures by 2-9°, imagine the effect 125,652 plants have had.  The trees JMDL plants today will provide shade in the future which would otherwise be sweltering concrete pads.  All it takes is the city and community partnering together to build a resilient and beautiful city for many more generations to enjoy. 

 



 

Charlie Sandberg

Charlie Sandberg

Charlie studied Sustainable Landscape Management at the New York Botanical Gardens, and is a current student at Arizona State University studying Organizational Leadership. 

He has overseen multiple installations, from small seasonal plantings to large and more complex multi-day installations.  He strives to produce the highest quality and detail oriented work while meeting any budget. Charlie manages a team of 4 Installations Foreman with a diverse background in landscaping.  He assists in coordinating daily field operations, ensuring all work is completed with an emphasis on client satisfaction. 

When Charlie is not at work, you may find him reading a book on architecture or history, but he also enjoys a great fiction novel as well.  He also loves CrossFit, and you may be able to spot him running the Central Park Loop with his wife Whitney.