More trees make cities better
They don’t lie off the coast of any country; these islands lie in the center. They can be hot enough to feel tropical. They hold millions of people and services; they are the hub of myriad lifestyles. And they not only contribute to but grow from climate change. Urban heat islands.
Urban heat islands are the areas inside cities that create, capture, and contain heat generated by the many machinations of urban life: buildings, machinery, exhaust emissions, waste, dense populations. Inside these centers of human activity, temperatures can be 1.8–5.4°F (1–3°C) higher[1] than the rural areas around them.
Rising heat increases the temperature of the air and pavement, which then contributes to rising water temperatures by heating storm water runoff. Rainwater in urban environments where pavement temperatures are 1000F (380C) can increase rainwater temperature up to 250F (140C).
For hot little kids, playing in the rain on hot pavement might be a great idea. When that heated rainwater drains into the sewer, however, it contributes to raising the temperature of neighboring streams, rivers, ponds, and lakes.[2]
For aquatic species, the warmed rain draining from sidewalks and reaching their habitat can be a death knell.
Many species rely on cool water temperatures in order to reproduce; warmer water can impede that reproduction. Over time, these types of changes among various species contribute to a general deterioration of the habitat’s natural balance.
But urban areas rich with trees help gather rainwater, sending it to the cool pavement beneath their branches and on to the watershed deep below.
REDUCING TEMPERATURES IN URBAN HEAT ISLANDS IS JUST GOOD BUSINESS.
Planting shade trees is one of the simplest and most effective ways to beat the heat in cities while putting the boil to business. According to the US Forest Service, “…consumers shop more frequently and longer in tree-lined commercial areas and are willing to spend more.”[3]
Shade trees help cool and preserve urban sidewalks and streets. Slowing their decay reduces greenhouse gas emission and decreases infrastructure maintenance costs.
One tree may reduce heat from both the sun and urban influences, but a number of trees planted near each other create a buffer for both heat and cold.
Research shows that even a young healthy tree can provide as much temperature reduction as 10 room-size air conditioners running 20 hours a day[4]. According to the USDA Forest Service, “Strategically placed trees save up to 56 percent on annual air-conditioning costs. Evergreens that block winter winds can save 3 percent on heating.”
Healthy mature trees help reduce energy demands and improve air quality by lowering greenhouse gas emissions. Each large tree can remove (sequester) as much as 48 pounds of carbon dioxide per year. And one large oak tree can contribute up to 40,000 gallons of water per year back into the air through transpiration[5]. Small wonder the air in a forest or park feels moist!
Add to those benefits the aesthetic beauty and pleasure trees give. Around a house or lining a street, they increase property values and decrease crime. Those beautiful shade trees are doing double duty for family and community.
In urban heat islands full of the waste products of traffic, manufacturing, and commerce, planting trees to remove both carbon dioxide and heat has a cumulative effect.
The more trees, the less pollution; the less pollution, the less heat; the less heat, the more comfort; the more comfort, the less conflict; the less conflict, the more safety; the more safety, the increased health; the increased health, the more vibrant the economy; the more vibrant the economy, the more peace.
All that from a bunch of trees just standing there, looking good and being cool.
How many trees can you plant by the end of the month? Who can you give one to?
What if we measured wealth by the number of trees we planted?
Increase your riches, plant a tree today!
[1] http://www.epa.gov/heat-islands
[2] http://www.epa.gov/heat-islands/heat-island-impacts#water
[3] http://www.fs.fed.us/learn/trees
[4] https://www.americanforests.org/discover-forests/forest-facts/energy/
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