Are cities around the world taking steps to provide adequate canopy cover from available trees to help mitigate increased temperatures from climate change? This is what a recent study published in Nature Communications hopes to address as an international team of researchers led by RMIT University in Australia investigated whether cities around the world were adhering to what’s known as the 3-30-300 rule, which stipulates buildings should have views of 3 trees, possess more than 30 percent of canopy cover, and be located within 300 meters walking distance of a park with canopy cover. This study holds the potential to help researchers, climate scientists, and the public better understand the necessity of canopy cover to help mitigate the impact of climate change around the world.
For the study, the researchers analyzed datasets obtained from more than 2.5 million buildings across eight major cities around the world (Amsterdam, Buenos Aires, Denver, Melbourne, New York, Seattle, Singapore, and Sydney) to ascertain if these cities were adhering to the 3-30-300 rule based on the datasets. In the end, the researchers found that five of the eight cities exceeded 50 percent of the “3” standard (Sydney, Singapore, Amsterdam, New York, and Seattle), only one city exceeded 50 percent for the “30” standard (Singapore) with one at 0 percent (Amsterdam). Additionally, only three cities exceeded 50 percent for the “300” standard (Sydney, Singapore, and Amsterdam).
“Previous research has shown depression, anxiety, obesity and heatstroke are more prevalent in urban areas that lack access to shady tree canopy and green open spaces,” said Dr. Thami Croeser, who is a research fellow from RMIT’s Centre for Urban Research and lead author of the study. “Canopy cover doesn’t just increase cooling, it can also reduce flood risk as well as benefit mental and physical health and support urban biodiversity. Studies say we actually need at least 40% canopy cover to substantially lower daytime air temperatures, so the ‘30’ metric is the absolute bare minimum - and most buildings we studied don't even reach that goal.”
Going forward, the researchers note that local governments should take steps to mitigate tree removal and trimming and striving to provide adequate canopy coverage to adhere to the 3-30-300 rule for the long term.
How will cities adhere to the 3-30-300 rule in the coming years and decades? Only time will tell, and this is why we science!
As always, keep doing science & keep looking up!
Sources: Nature Communications, EurekAlert!
Featured Image: Canopy cover in a park. (Credit: Thami Croeser)
