Whenever I fly above Salt Lake City and look out at all the blank and boring rooftops in the valley, I wish there was something better to do with that empty space.
It turns out there is. And it might just save us.
If each rooftop were a forest, no one would even be able to spot where the mountains end and the city begins. Everyone who flies into the Wasatch Front would be amazed by the greenery and the hidden civilization beneath it.
Rooftop forests would be tree gardens installed on the top of department stores, malls, industrial buildings, skyscrapers and wherever else trees or other vegetation could be planted.
A study conducted last year by Crowther Lab shows that 1 trillion more trees planted would save the world. The problem with planting that many trees isn’t finding saplings; it is finding the space for them.
Crowther Lab reports it would take 1.6 million hectares of land to sustain that many trees. That’s about the size of China, roughly 10% of Earth’s land area.
Salt Lake City is nowhere near that size. But if we don’t lead this cause, who will?
The Salt Lake Valley is 1,300 square kilometers in area, about 130,000 hectares. If rooftop gardens were installed, our community would be well on the way to helping combat climate change through vegetation.
“Building rooftop gardens requires careful planning,” landscape architect and Utah State University professor David Anderson said, “but if everyone started doing it, it would be great for battling climate change.”
In Ecuador, biologist Liliana Jaramillo Pazmiño is fighting climate change one rooftop at a time. She believes bringing more vegetation into cities will make cities more resilient to drought, flooding and higher temperatures.
Really? Planting trees on rooftops would fight flooding and high temperatures? Yes. The roots of the trees would soak up the runoff that normally floods the streets. Studies from the Arbor Day Foundation show trees lower the temperature anywhere from 10 to 20 degrees Fahrenheit in urban heat islands.
Not only will rooftop forests make cities more sustainable but they also have proved to lower crime rates. That’s what University of Colorado professor Austin Troy discovered when he led a study on tree canopies and crime rates. The result? People in cities that had more trees were less likely to experience fear and aggression while being out and about. And not just a little. The study indicated that a 10% increase in tree canopy caused roughly a 12% decrease in crime.
Ecologists, climatologists, botanists and landscape architects need to come together to create rooftop forests where vegetation can thrive inside an urban environment.If our state wants to start making serious strides toward a more sustainable future and better air quality, we need to dream bigger than installing recycling bins in parks.
If Salt Lake City leads, others will follow. And one day, when we look down on cities around the world, we’ll wonder where they are.
Jonah Hansen
Jonah Hansen, Logan, is a student at Utah State University majoring in economics. He hopes to go into environmental economics.