As cities around the world face record temperatures, New York’s bold environmental experiment is attracting new attention. Between 2007 and 2015, the city planted one million trees across its five boroughs under the MillionTreesNYC initiative — a nearly $400 million campaign aimed at making one of the world’s most densely populated cities cooler, greener and more resilient.
More than a decade later, as climate change fuels longer and more intense heatwaves, the project’s impact is becoming increasingly clear.
Mature tree canopies now shade streets that were exposed to harsh summer sun, helping to combat the urban heat island effect while improving air quality and public health. The campaign has also become a model for cities looking for nature-based solutions to rising temperatures.
More than just planting trees
The initiative was not just about increasing green spaces. It sought to transform New York’s urban landscape by planting trees in parks, along streets, in schools, public housing complexes, and deprived neighborhoods that had historically had little shade.
The effort was driven by a partnership between New York City Parks and the New York Restoration Project, founded by singer and environmental activist Bette Midler. The goal of planting one million trees was achieved ahead of schedule in 2015.
Why trees matter in a warming world
Cities are much hotter than their surrounding rural areas because asphalt, concrete and buildings absorb and retain heat – a phenomenon known as the urban heat island effect.
Trees help counteract this in two important ways:
- Their canopies prevent direct sunlight from reaching roads and buildings.
- Through evaporation, trees release moisture into the air, which naturally lowers ambient temperatures.
According to New York City officials, expanding the tree canopy reduces cooling costs, filters pollutants from the air, captures rainwater, and provides significant public health benefits. The city’s urban forests now provide an estimated $120 million in environmental and economic benefits each year.
The issue of climate justice
One of the biggest lessons learned from the project is that not all neighborhoods experience heat equally.
Studies have shown that low-income communities and neighborhoods with fewer trees often record much higher summer temperatures and face greater health risks during heat waves. Recognizing this fact, New York’s recent Urban Forestry Strategy prioritizes agriculture in heat-prone areas to reduce inequalities in climate resilience.
Instead of stopping after a million trees, New York has shifted its focus toward preserving mature trees while expanding canopy coverage further. City leaders have set an ambitious goal of increasing the tree canopy to about 30% by 2040, with new investments targeting neighborhoods most vulnerable to extreme heat.
