Trees Are Cool(ing)

Did you know that San Francisco is the third-fastest-warming city in California? Fortunately, there’s a simple solution that can change this trajectory. Trees can cool cities through shade and transpiration — the release of water into the atmosphere, which cools the air as it vaporizes.

Peppermint Willow (Agonis flexuosa)

In our four decades of work, Friends of the Urban Forest has planted more than 60,000 trees, which have sequestered over 100 million pounds of CO2. That’s a lot of carbon removed from our atmosphere! Trees = green infrastructure = climate resiliency.

That said, San Francisco remains behind major cities in tree canopy coverage and thousands of San Franciscans — including seniors, people with disabilities, young children, and other vulnerable people — don't yet have the protections that trees provide.

Using environmental justice as our guiding principle, our work moving forward is to address this inequity. To maximize the effectiveness of our work, we're focusing our outreach, tree planting, and follow-up tree care efforts in neighborhoods that are least protected by trees from future extreme heat events. These neighborhoods tend to:

• have fewer economic, political, and social resources

• be closer to high traffic thoroughfares and highways

• have more people prone to respiratory health conditions due to high level of toxins in the air

In the map at left, from the Dept. of Public Health, shades of red show where San Franciscans are most vulnerable to health impacts from extreme heat. The map at right shows where Friends of the Urban Forest is planting trees.

We're partnering with neighbors and community-based organizations to ensure they have input and participation every step of the way.

As evidence grows that warmer years lay ahead, we're reassured to belong to a community that's taking positive action — and we're glad you're part of it!