How mapping trees in America's cities could fight inequality and slow climate change

I still remember the temperature rising in our apartment. My wife, bedridden after a fall, looked at me with fear in her eyes. You see, the air conditioner had broken in our small apartment during a heat wave, and suddenly the sun outside our window became a threat, magnified by an ocean of boiling pavement and lack of any trees to cool our building.

We were fortunate. I had enough financial credit to get the AC fixed on an emergency basis, and to run out and buy a bevy of high tech fans that just barely got us through until the repairs were complete.

Many Americans who suffer heat waves are not so fortunate, and fall ill and die because of heat stress. In fact, heat is the 'silent killer' that takes more lives each year than any other extreme weather.

That is why we need 'Tree Equity' in our cites to bring natural cooling to every neighbourhood. Trees are nature’s air conditioning, reducing neighbourhood temperatures by as much as 10 degrees Fahrenheit. For people who don’t have air conditioning, or can’t afford to operate it full bore, this natural cooling can save lives and hospital visits.

What we have right now is the opposite. You see, a map of tree cover in the United States’ communities is also a map of income and race inequality. This means that the people most likely to have pre-existing health conditions and least likely to have air conditioning are being denied the cooling benefits of trees.

The threat of COVID-19 magnifies health dangers from heat. Potential COVID exposure limits people’s ability to seek relief in cooling centres. Respiratory stress from air pollution makes people more vulnerable to COVID infection.

Fixing this problem starts with seeing it. We need to put our tree inequities on a map and show where they put people most dangerously at risk.

That’s why my organization, American Forests, has launched the Tree Equity Score. This is the first national effort to rate tree cover in every neighbourhood of every American urban area against race, age, economic status, density, and heat risk.

Tree Equity Score provides maps and data to show exactly where we are failing to deliver trees as heat protection for urban neighbourhoods, and where this matters most. It is a challenge to America to step up and create Tree Equity across our cities.

The first pilot Tree Equity Scores cover multiple cities and towns in Maricopa County, Arizona (home to Phoenix), the San Francisco Bay area of California and Rhode Island. They confirm the urgent need to plant, protect and take care of more trees in socio-economically disadvantaged neighbourhoods.

Tree Equity Score will enable state and local leaders, and their partners, to see where increased tree planting, tree care and tree protection are most urgently needed. This creates a roadmap for public and private investment, from dollars to volunteer hours.

As a way to help communities use the Tree Equity Score, American Forests has also developed an online Tree Equity Score Analyzer, using Rhode Island as the initial proving ground. This publicly available online tool allows the user to analyze how the Tree Equity Score for any neighbourhood relates to specific properties that might be considered for tree planting and other urban forestry projects.

Committing to Tree Equity can do more than protect cities from climate change—it can also slow climate change and save residents money. That’s because urban trees reduce residential energy use for heating and cooling by an average of 7.2%, saving homeowners $7.8 billion dollars and reducing greenhouse gas emissions. Urban trees across America also absorb almost 130 million metric tons of carbon dioxide annually. Taken together, this makes urban trees a powerful climate solution.

Tree Equity is a job creator, generating 25.7 jobs per $1 million invested in urban forestry. This investment must be delivered in close partnership with community leaders and residents so that this work is done together, and local residents can access this economic opportunity.

There are promising signs for Tree Equity. Cities and their private sector partners are embracing this challenge, including pledges from Dallas, Tucson, Boise, Detroit, and the Chicago Regional Trees Initiative to the US Chapter of 1t.org. Bipartisan legislation such as the TREE Act is progressing through the US Congress, pledging much needed federal funding to match these efforts.

Now we must finish this job. Tree Equity Score calls us all to action—governments, companies, NGOs, civil society, and individuals. We can no longer ignore that our urban tree gaps magnify serious inequities and injustices, and put lives at risk. Let’s make Tree Equity one of many steps we take to build back better together.