NYC’s Growing Urban Forests 🌳
by Sonam Velani and Kathy Zhang
New Yorkers enjoying the tree shade. (photo via Nature Conservancy)
How trees protect us from extreme heat
NYC’s 100°F+ heat wave last week was inescapable, and it’s just one small part of this year’s global extreme heat events exacerbated by climate change. Extreme heat is deadly, and 21 of Earth's 30 hottest days on record occurred in July. In addition to rising temperatures, climate change is also ramping up humidity, which makes it harder for our bodies to cool down by creating a sauna-like environment (also known as “muggy” or “gross”).
On these increasingly common blistering days, the coolest parts of NYC are around major parks. Among its many benefits, tree cover (“tree canopy”) helps to offset the urban heat island effect, and urban neighborhoods without much vegetation can be up to 20 °F hotter than areas with abundant green spaces, disproportionately impacting marginalized communities.
Growing momentum across the city
NYC has approximately 7 million trees, which provides around 22 percent tree coverage across the five boroughs. The latest NYC Strategic Climate Plan (aka PlaNYC) targets 30 percent tree canopy cover, an ambitious goal supported by recent bills introduced in the New York City Council’s Committee on Parks and Recreation.
The city manages land accounting for around 57 percent of tree canopy in NYC, while private land accounts for 35 percent, with the remainder split between state and federal ownership. In 2021, the Nature Conservancy launched the multi-sector Forest for All NYC coalition – now with over 80 member organizations – to help realize the community, equity, and climate benefits of a larger, well maintained tree population.
Measuring urban forest growth locally & globally
Accurate monitoring is critical to forest planning, planting, and maintenance efforts. To create and update its tree inventory, NYC uses i-Tree software developed by the US Forest Service. NYC volunteers augment and verify this data – over 2,200 residents helped park officials survey street trees in the last 2016 TreesCount! census. At global scale, scientists layer aerial/satellite imagery with LiDAR (light detection and ranging) data to estimate tree coverage, height, and even species!
by Sonam Velani and Kathy Zhang