Trees Are Cool – Even During a Drought!

April 28, 2023

Trees Offer Climate Change Solutions

On February 7, 2023, Mayor John Giles of Mesa, Arizona, announced the ‘Trees Are Cool’ initiative to increase shade across the city, lower the urban heat island effect in neighborhoods, and help cool our communities during the hot summer months. “Trees Are Cool” challenges residents and businesses to help increase the City’s tree canopy coverage to 15 percent over the next 27 years. To reach this crucial milestone, Mesa has set a target of planting 1,000,000 trees in Mesa by 2050.

Mayor John Giles during State of the City 2023
Mayor John Giles introduces the ‘Trees Are Cool’ initiative during his February 7th State of the City address.

Every desert dweller has experienced how much cooler it feels on a hot day when standing in the shade of a tree rather than in the full sun. That effect has become increasingly important as cities help people cope with higher summer temperatures. And Mesa isn’t the only city with a focus on tree plantings in Arizona. Phoenix, Tucson, and others are also taking part in the effort.

Cooling vulnerable neighborhoods and low-income areas is even more important  because they often have less green spaces and tree canopy. American Forests, a nonprofit tree advocacy organization states that the wealthiest neighborhoods in the U.S. have 65% more tree cover than the neighborhoods with the highest poverty levels.

Cooling Stations and Hydration Stations
Cooling Stations and Hydration Stations provide water to the public during extreme heat events in Mesa.

Even better, trees don’t just reduce heat. They play a crucial role in our ability to meet climate action goals by absorbing carbon and other greenhouse gas emissions that are highly concentrated in our cities.

Key Tree Benefits
  • Clean the air and produce oxygen
  • Help to reduce energy use
  • Filter rainwater and play a role in the water cycle (see below)
  • Slow stormwater & flooding
  • Provide habitat for wildlife (shelter, food, and breeding sites)

Besides all of the functional benefits, trees also provide beauty and other aesthetic benefits. And, studies continually show that they contribute to better mental health. Trees help people feel serene, peaceful, and better connected with nature. They significantly reduce workplace stress and fatigue while also decreasing the recovery time following medical procedures. Green spaces can also help lower the amount of criminal activity in a community.


Tree planting
Corporate partners, Shutterfly and The Boeing Company, partnered with Skyline High School, Arizona Sustainability Alliance and the City of Mesa to plant 20 trees at Skyline Park in Mesa, AZ.


“Why are you planting trees? Don’t you know we’re in a drought?”

Without Trees We Become Hotter and Drier

But what about the water needed to establish and maintain tree planting efforts? Quotes similar to the one above are often heard as a response from the public in reference to tree planting goals. In a blog by American Forests titled “No Trees Means No Rain” they describe how removing trees can lead to desertification (becoming hotter and drier), and how trees play a vital role in sustaining the water cycle. This is the process by which water circulates between the earth’s bodies of water, atmosphere, and land.

Trees not only help to ‘plant the rain’ by intercepting the water and helping it to absorb into the soil below, but they also eventually evaporate that moisture through their leaves releasing it back into the atmosphere. Shade from the trees further helps to reduce evaporation from the moisture in the soil around it, and helps to reduce water needs of plants surrounding it.

Trees not only prevent soil erosion by stabilizing the soil, they also help improve the quality of our water. This is especially true with polluted stormwater from our streets. Tree roots in healthy soils will absorb or break down water pollutants including metals, pesticides, and solvents.

Even though we are in historic drought conditions, trees can be responsibly planted and maintained. Desert cities need to focus on two main criteria:

  1. Plant native trees or those that are desert adapted from other regions. These trees can often survive on natural rainfall once established.
  2. Embrace low impact development and rainwater harvesting. The practice reduces landscape water use while remediating polluted runoff before it reaches natural waterways.
Water Harvesting Sign
This project, located at Mesa Urban Garden, 212 E 1st Ave. in Mesa, demonstrates specially designed landscaping, including curb cuts, to help capture and beneficially use stormwater runoff from the street and sidewalk.
April 28, 2023 is Arbor Day!

The national Arbor Day is celebrated each year on the last Friday in April. It’s a holiday that celebrates the planting, upkeep, and preservation of trees in our communities. With all of the benefits listed above, you can see how trees can truly contribute to a vibrant and sustainable community – especially in our desert environment. That’s why many of our Water – Use It Wisely Partners provide programs and classes to help our residents with tree selection and maintenance ideas. One of our partners (SRP) even gives away trees to help reduce their customers’ energy bills! And, did you know that saving energy can save water, too?

City of Mesa ‘Trees AreCool’ – Plant a Tree, Record Your Tree

As part of the “Trees Are Cool” initiative, Mesa launched an online tool to record newly planted trees, including planting locations. This data, in tandem with the assessment of existing trees, will help the City track its efforts to reach the goal of 15 percent tree canopy coverage (and 1,000,000 million trees planted). Additionally, the page features a map showing Mesa neighborhoods at greater risk of heat impacts – which often correlates with lesser amounts of tree canopy – and provides helpful information on choosing, planting and caring for trees. For additional information about the tree project and to record your new tree, visit

Find these additional tree-mendous blogs on this topic:

Donna DiFrancesco is a Conservation Coordinator with the City of Mesa, AZ, one of 19 Water – Use It Wisely partners to offer water-saving advice and programs.