Hot cities — what’s happening to the trees?
Effects of Climate Change 1.5
Urban areas are becoming warmer, and this effect is called the Urban Heat Island Effect. What it means is that metropolitan areas are warmer than surrounding areas.
How do these form?
Let’s first take note of all of the roads that cities have within its city limits. What was there before roads? Vegetation. By replacing vegetation with asphalt roads and concrete, we are essentially turning up the thermostat because these materials absorb sunlight instead of reflecting it.
Tall buildings and street width size also contribute to the rising temperature in urban areas by preventing substantial air flow to ‘sweep’ away the heat. And obviously, vehicles and factories add to the rise in urban temperature. And we can’t forget about air conditioning: a staple during the summer.
In two thirds of the cities analyzed (41 of 60), urbanization and climate change appear to be combining to increase summer heat faster than climate change alone is raising regional temperatures. — Climate Central
It’s all well and good to learn about the urban heat island effect, but what where do trees come into this?
Almost there. Let’s note a significant impact of warming urban areas — increase in pest presence in street trees. As with many areas around the world, an increase in temperature means a higher abundance of pests.
Researchers at North Carolina State University found that street trees with pests had less branch growth than trees without pests. They also found that regardless of pests, the heating-up of urban areas negatively impacted tree growth and photosynthesis. Trees in warmer urban areas had less tree growth overall.
“We found that urban warming reduced carbon storage by all of Raleigh’s willow oaks by 12 percent, or 27 metric tons per year,” Meineke says.
If we’re trying to stop Climate Change, then we can’t let this be happening to the trees. There are many ways that the urban heat island effect can be reduced. Here’s a few:
- Plant more trees and plants!
- Invest in green roofs
- Use cool pavements (check out this source on possible solar pavements!)
Let’s individually watch our energy consumption and plant more green, and as a whole, change our direction towards a more sustainable and tree-friendly future.
Claudia A.
References:
Climate Central. Hot and Getting Hotter: Heat Islands Cooking U.S. Cities http://www.climatecentral.org/news/urban-heat-islands-threaten-us-health-17919 (accessed Oct 6, 2016).
Donegan, B. Urban Heat Islands: Why Cities are Warmer than Rural Areas https://weather.com/science/weather-explainers/news/urban-heat-island-cities-warmer-suburbs-cooler (accessed Oct 6, 2016).
EPA. Heat Island Cooling Strategies https://www.epa.gov/heat-islands/heat-island-cooling-strategies (accessed Oct 6, 2016).
North Carolina State University. Urban warming slows tree growth, photosynthesis https://www.sciencedaily.com/releases/2016/10/ 161005101427.htm (accessed Oct 6, 2016).
