Trees are necessary for S.F.’s future as climate change worsens and heat rises.

Trees are necessary for S.F.’s future as climate change worsens and heat rises.

Trees are necessary for San Francisco’s future

Earlier this week, San Franciscans had the rare opportunity to leave their light sweaters at home and take their shorts out for a spin.

Earlier this week, San Franciscans had the rare opportunity to leave their light sweaters at home and take their shorts out for a spin. It’s always nice to be reminded that summer is a warm season. But it’s also a relief when the cooling fog blows back to blanket our City.

Some San Francisco neighborhoods — especially n the southeast and western parts of The City — don’t have enough trees to shade the sidewalk and cool the air. In other areas, necessary removals of unhealthy and hazardous trees are shrinking the canopy further. In fact, San Francisco has one of the smallest urban forests out of all the major cities in the country.

This must change. As climate change worsens, so will hotter days and more unpredictable weather. In addition to lowering temperatures, a flourishing “green infrastructure” system can suck up storm water, clean the air, lower stress and help draw carbon dioxide out of the atmosphere.

“Tree planting is among the most cost-effective and tangible local actions we can take to mitigate global warming,” Ben Carlson of the nonprofit Friends of the Urban Forest told me.

But San Francisco struggles to give trees the money and protection they deserve.

It costs about $500 to replant a tree and $500 per year to water. Currently, The City doesn’t have a funding source to pay for these requirements during the first three years. But Mayor London Breed is supportive of dedicating $2 million to replanting and watering in the budget. Now advocates are urging the Board of Supervisors to fully fund replacement of over 4,000 trees over the next two years with an additional $2 million.

“I am hopeful they will find a solution,” Carlson told me.

The urban canopy is also often wrongly viewed as incompatible with housing and public transit efforts. Earlier this year, general contractor Webcor Builders illegally removed two sidewalk sycamore trees during construction of a new condominium at 2465 Van Ness Avenue. Then last month, a developer illegally removed five trees while building a residential building at 1140 Harrison Street after The City denied its permit.

Although technically legal, yet in conflict with its own urban forest policy, The City is also removing trees as part of public transit projects. For example, plans for the Better Market Street project, which were displayed at an open house last week, include new bike lanes, utility improvements and the removal of all existing trees along Market Street. In 2016, San Francisco lost 194 mature trees when The City started construction along Van Ness Avenue.

“Transit infrastructure has been on a collision course with urban greening,” Diana Scott, a Sunset resident and tree advocate, told me. “It should be an ‘and both’ rather than an ‘either or’ equation.”

Re-valuing trees, both with funding and greater protections, is critical to keeping San Franciscans safe and healthy during the era of climate change. Supervisor Gordon Mar has called for a hearing on The City’s urban forest management and is working with the Public Works Department to increase tree planting and maintenance as part of the Sunset Boulevard Master Plan. Last week, was the first of three community meetings on the topic.

“San Francisco added a net increase of one tree last year, thousands of trees short of our goal, and continues to fall behind other major cities in expanding and caring for our urban canopy,” Supervisor Mar told me. “We must identify and address the barriers to meeting our goals to green our City, including collecting and tracking data on our canopy, and funding, management, and oversight across the departments responsible for tree planting and maintenance.”

San Franciscans may rely on fog to keep us cool now, but trees are necessary for San Francisco’s future. Levels of carbon dioxide in the atmosphere are the highest they’ve been in 800,000 years. Wildfire smoke is already blowing over Northern California. If The City is going to properly respond to the “climate emergency” it declared, it must let our urban canopy thrive.

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Robyn Purchia is an environmental attorney, environmental blogger and environmental activist who hikes, gardens and tree hugs in her spare time. She is a guest opinion columnist and her point of view is not necessarily that of the Examiner. Check her out at

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