Tucson Arizona climate change trees

Planting a million trees in the semi-arid desert to combat climate change

Tucson's ambitious tree planting goal aims to improve the health of residents, wildlife, and the watershed.

Reflecting on her childhood, Tucson, Ariz., Mayor Regina Romero points to her father as the figure who lit an environmentalist fire within her.


Any chance he'd get, Romero's father would take his wife and six kids to an 800-acre ranch in the Sierra Madre mountain range of Sonora, where they learned how to ride horses, direct cattle, and to respect the wildlife, such as bobcats and brown bears.

"We invaded their space," he would tell them.

At the ranch, there was an outhouse instead of running water, rivers instead of showers. It was very rudimentary, Romero told EHN.

But riding through these biodiverse mountains on horseback made it all worth it.

"It was just so liberating," Romero said.

Five years ago, Romero's father passed away. Still his legacy lives on, as Romero, the first-ever Latina mayor of America's 33rd largest city, uses her platform to build an environmentally resilient community.

\u200bRegina Romero, mayor of Tucson, Arizona

Regina Romero, mayor of Tucson, Arizona. (Credit: Wikimedia Commons)

In Feb., Romero solidified a pledge to plant 1 million trees in the semi-arid desert city by 2030, when she joined the 1t.org US Chapter Stakeholder Council, a group of public, private and nonprofit leaders committed to the restoration of 1 trillion trees globally.

The U.S. chapter, including REI, National Forest Foundation, Amazon, the City of Dallas and the City of Tucson, have committed to more than 1 billion trees thus far.

Romero's goal: adapting to a rapidly changing climate in the country's third fastest warming city.

"Climate change waits for no one," Romero said. "Without a liveable community, we have no Tucson."

Currently, Tucson supports an estimated 1.6 million trees.

Low income neighborhoods hit hardest

Romero, urban forestry manager Nicole Gillet, and local groups such as Tucson Clean and Beautiful, are prioritizing tree-planting in low-income communities, which are disproportionately burdened by Tucson's urban heat island effect.

"We have to attack the problem where the problem exists," Romero said.

According to a Climate Central report, Tucson has warmed by 4.48 degrees Fahrenheit since the first Earth Day in 1970, which is more than Phoenix, 110 miles to the north.

Recent research shows that some Tucson neighborhoods are up to 8 degrees F warmer than the city's average. Neighborhoods with the highest Latino populations are 4 to 5 degrees F warmer on average.

"It's not that the heat is seeking out low-income populations," lead author, John Dialesandro, a Ph.D. candidate studying urban climatology at University of California, Davis, told EHN. "It's a lack of greenspace."

In the desert Southwest, the extra heat that low-income neighborhoods endure often coincides with lack of air conditioning. Many households must choose between air conditioning, healthcare, and food, one University of Arizona paper said.

These communities with less indoor cooling often have fewer trees to provide shade as well.

Some Tucson neighborhoods with high poverty rates are only 1 to 2 percent shaded by tree canopy, according to an American Forests tree equity map.

This is an issue of public health, Adriana Zuniga, an assistant research scientist in the University of Arizona's College of Architecture, Planning and Landscape Architecture, told EHN.

"It affects quality of life," Zuniga said. "Vegetation is linked to better air, lower temperatures, less stress, studies show less use of antidepressant medication."

Trees help biodiversity

arizona trees

2020 was Tucson's driest year on record, at only 4.17 total inches of rainfall. (Photo credit: Sean Benesh/Unsplash)

According to Zuniga, urban vegetation can also alleviate issues facing desert biodiversity, especially migratory species.

"Their habitats have been fragmented so much from urbanization that every spot of vegetation counts," Zuniga said.

Migratory pollinators are declining in the Sonoran Desert. More than 10,000 pollinator species are at risk in the Southwest, according to the Desert Botanical Garden in Phoenix.

The monarch butterfly, known for its remarkable blood-orange wings, is a keystone species that relies on nectar resources in southern Arizona during its spring migration.

Over the last two decades, monarch populations have fallen by 80 percent. Some of the causes include climate change, drought, deforestation and declines in milkweed plants, which female monarchs rely on for laying eggs.

"They desperately, desperately need our help in developing those patches of habitat for them to use while they migrate back and forth from Mexico, all the way to Canada," Zuniga said.

Restoring the watershed during a drought

Trees need water. And the Southwest is in a drought.

2020 was Tucson's driest year on record, at only 4.17 total inches of rainfall.

Thus, planting 1 million trees in the next decade has faced criticism.

But Lisa Shipek, executive director of Watershed Management Group in Tucson, believes that the initiative is realistic if native, drought-tolerant trees are planted.

"Velvet mesquite trees, desert ironwood, blue palo verde—there are a number of trees that are very appropriate to plant in the city, are found at these low elevations, and can be sustained just on rainwater," Shipek told EHN.

In fact, Shipek said, planting 1 million trees could actually restore parts of the Tucson watershed.

Before the mid-1900s, Tucson had a platter of perennially flowing rivers and creeks, such as the Santa Cruz River, Rillito River, and Sabino Creek. Then came over-pumping and massive urban development.

Now, it is rare to see flowing water.

In urban areas, where much of the surface is paved and impermeable, the million tree initiative could allow more rainfall to reach Tucson's watershed, according to Shipek.

"Putting in a rain basin with every single tree will help restore the watershed and ensure more water is infiltrated where the rain is falling," Shipek said.

A rain basin is a surface that allows rainwater to soak in and feed the trees, and indirectly, Tucson's groundwater. Groundwater contributes to streamflow.

Rainwater will be the primary fuel for the million trees initiative. When Romero entered office, she and her council approved a green stormwater infrastructure fee, which charges the average residential water-user $1 per month. Over the next three years, the fee will generate up to $7 million for sustainable stormwater harvesting in parks, streets, and parking lots, according to Romero.

Relying on rain in a drought is tricky, but according to Katie Gannon, program director at Tucson Clean and Beautiful, rain will reach these trees by way of nature. When more trees are present, the surrounding air becomes cooler, causing more clouds to drift into the low-pressure system, she told EHN.

"Green attracts rainfall," Gannon said.

Banner photo: Tucson, Arizona. (Credit: Manny Pacheco/flickr)

climate change drives bc watershed plans

Climate change drives BC’s push for new watershed plans

The government wants the public to weigh in on the future of water. Critics wonder if the plan will go far enough.
Sunrise in the woods

Get our Good News newsletter

Get the best positive, solutions-oriented stories we've seen on the intersection of our health and environment, FREE every Tuesday in your inbox. Subscribe here today. Keep the change tomorrow.

Climate change fueled $329 bln in 2021 economic losses

Climate change fueled $329 bln in 2021 economic losses, 3rd costliest year ever

The world racked up $329 billion in economic losses linked to severe weather last year, and only 38% of that bill was covered by insurance, Aon says.

Environmental law explained: How to stop climate change using the law

Gluing yourself to the road is one way to protest environmental collapse. Suing fossil fuel companies is another.
climate civil disobedience
Photo by Ma Ti on Unsplash

Interest in civil disobedience has reached a mini climate tipping point

As each hellish new natural disaster is matched by an equally hellish political stalemate on climate legislation, a growing segment of the American population is thinking: What can I personally do to get some climate action going here?

climate media action Justin McBrien
Photo by Bryan Goff on Unsplash

Justin McBrien: Disaster flicks like ‘Don’t Look Up’ won’t spur climate change action. Here’s why

The climate crisis is very different from an errant asteroid. Stopping it demands far more than listening to scientists and trusting their technical solutions.

Judges appear skeptical of Big Oil's climate claims
Photo by Robert Linder on Unsplash

Judges appear skeptical of Big Oil's climate claims

A panel of judges appeared skeptical yesterday of giving federal courts exclusive rights to hear climate change cases against fossil fuel firms.

children climate books
Photo by Annie Spratt on Unsplash

New children’s book explains systemic nature of climate change

Most kids’ books about the environment encourage children to adopt Earth-friendly habits like taking shorter showers and recycling. But in a new release called “A Kids Book About Climate Change,” the authors focus on the bigger picture.

From our Newsroom
Africa cooking pollution

What do new cookstoves in Ghana and air conditioners in NYC have in common? Energy justice.

Combating energy poverty and energy insecurity are critical elements to achieving environmental health equity for billions worldwide.

dr. fauci

Peter Dykstra: Life imitates climate politics—again.

Personal, misinformed attacks on Dr. Fauci are reminiscent of climate spats over the decades.

Don't look up climate change

Hollywood’s third strike on climate change?

"Don't Look Up" is ambitious—but trips over its subject matter.

environmental news

5 popular reads from our newsroom in 2021

Check out what sparked readers' interest over the past year.

journalism

Our top 5 long reads of 2021

Check out must-read, in-depth reporting from the past year.

butterfly

Our top 5 good news stories of 2021

It's not all doom and gloom.

Stay informed: sign up for The Daily Climate newsletter
Top news on climate impacts, solutions, politics, drivers. Delivered to your inbox week days.