A new study highlights the dire need for increased tree canopy cover in cities like New York, Amsterdam and Buenos Aires, revealing how failing to meet green space benchmarks is exacerbating urban heat issues and impacting mental and physical health.
A recent study led by RMIT University has unveiled concerning shortfalls in tree canopy cover across major global cities, highlighting a pressing need for urban green infrastructure to combat rising temperatures and enhance public health.
The research spans eight prominent cities, including New York, Amsterdam and Buenos Aires, analyzing over 2.5 million buildings through the innovative ‘3-30-300’ rule.
This emerging benchmarking system, shaped in collaboration with the Technical University of Munich, advocates that every residence, educational institution and workplace should have a view of three trees, be within a neighborhood consisting of 30% canopy cover and be situated within 300 meters of a park.
Cities like Seattle and Singapore are leading by example, with 45% and 75% of their buildings meeting the 30% canopy requirement, respectively. However, New York and Amsterdam have scored alarmingly low on canopy cover, despite a plethora of visual access to trees.
Lead researcher Thami Croeser, an RMIT University research fellow, expressed significant concern over these findings.
“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,” Croeser said in a news release.
Urban areas are particularly feeling the heat, with 2023 having recorded unprecedented temperatures.
“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,” he added.
Croeser further pointed out that current urban planning practices are detrimental to healthy tree growth, largely due to prioritizing infrastructure such as cabling and pipelines over green space.
“We need to stop thinking that allocated spaces for buildings and roads are permanent when they could be reallocated to prioritize green infrastructure,” he added.
The impediments facing urban trees are pronounced. Croeser noted that trees are frequently planted in compacted soil covered by asphalt, which prevents essential rainwater from nourishing the soil. Moreover, urban trees are often replaced with saplings or heavily pruned, impeding the growth of robust canopy trees.
“Earlier research shows that if urban trees are planted in better quality soil with enough space for them to grow, where rainwater can run directly into the soil, it will help trees grow bigger faster to address our lack of canopy cover,” added Croeser.
The ‘3-30-300’ rule, created by Dutch urban forestry expert Cecil Konijnendijk, is already gaining traction globally.
Wolfgang Weisser, a professor of terrestrial ecology at the Technical University of Munich, emphasized that the rule’s localized approach offers a more accurate evaluation of urban greenery compared to traditional metrics.
“Some of the metrics we use now are not really sufficient whereas the ‘3-30-300′ metric really demands that nature is brought to the areas that people actually live and work in,” Weisser said in the news release.
The researchers collaborated with Dutch firm Cobra Groeninzicht to visualize the data, facilitating the application of the ‘3-30-300’ benchmarks for cities globally.
“With the techniques our team has developed, we can calculate the ‘3-30-300’ benchmark for any city in the world,” added Dirk Voets, senior advisor geospatial at Cobra Groeninzicht.
Published in Nature Communications, the study underscores a clear call to action for urban planners and policymakers worldwide to reassess and reframe their approach to urban greenery.
As cities grapple with rising temperatures and the associated health risks, integrating sufficient canopy cover into urban design emerges not just as a goal but a necessity.