A study by researchers from the University of Wisconsin-Madison has found that increased tree coverage can help to mitigate the effects of the “heat island effect” in urban areas. This occurs when cities absorb and trap heat due to the presence of impervious surfaces such as concrete and asphalt. The study analyzed satellite imagery from 28 Midwestern cities over an 11-year period and found that cities with increased tree coverage had lower surface temperatures during the summer months. Trees reduce the heat island effect by providing shade and transpiring, which cools the air around them, and they absorb heat from the sun to reduce amounts absorbed by buildings and roads.
Tree coverage reduces heat island effect in cities, study finds
As cities continue to grow and expand, urban areas in particular are experiencing an increase in temperature, known as the “heat island effect”. This phenomenon occurs when cities absorb and trap heat due to the presence of impervious surfaces such as concrete and asphalt. However, a new study has found that increased tree coverage can help mitigate the effects of the heat island effect.
The study, which was conducted by researchers from the University of Wisconsin-Madison and published in the journal Climate, looked into the relationship between tree coverage and surface temperatures in 28 Midwestern cities. The researchers analyzed satellite imagery from the cities to measure changes in tree coverage over a period of 11 years, from 2001 to 2011.
The findings showed that cities with increased tree coverage had lower surface temperatures compared to those with less tree coverage. The study found that an increase in tree coverage of just 10% resulted in a 0.6 degree Celsius decrease in surface temperature during the summer months.
How do trees reduce the heat island effect?
Trees reduce the heat island effect by providing shade and transpiring, which cools the air around them. Shade from trees can reduce air temperature by up to 8 degrees Celsius, according to the US Department of Energy. Trees also absorb some of the heat from the sun, reducing the amount that is absorbed by impervious surfaces such as roads and buildings. Additionally, trees release water vapor through transpiration, which cools the surrounding air.
Other benefits of urban trees
Urban trees provide a number of benefits beyond reducing the heat island effect. They can improve air quality by removing pollutants from the air, and they provide a habitat for wildlife. Trees also help to reduce noise pollution, and they improve the aesthetics of urban areas, making them more appealing places to live and work.
What types of trees are best for reducing the heat island effect?
Trees with large, spreading canopies are best for reducing the heat island effect, as they provide the most shade. Some examples include oak trees, maple trees, and sycamore trees.
How many trees are needed to make a significant impact on the heat island effect?
The exact number of trees needed to make a significant impact on the heat island effect will depend on various factors such as the size of the city and the current level of tree coverage. However, research suggests that increasing tree coverage by just 10% can make a significant difference in surface temperature.
Are there any downsides to planting trees in urban areas?
While the benefits of urban trees are numerous, there are also some potential downsides. Trees can be expensive to plant and maintain, and they may require regular pruning to prevent damage to buildings or sidewalks. Additionally, some types of trees may be more prone to attracting pests or causing allergies.
The findings of this study highlight the importance of tree coverage in mitigating the effects of the heat island effect in urban areas. As cities continue to grow and expand, incorporating more trees into urban landscapes can provide numerous benefits beyond just reducing surface temperature.