Trees Are a Cool Solution in the Heat of the Moment

Trees can help reduce the risk of heat-related illness and, in some cases, save lives.

Residential Shaded Sidewalk with Green Trees in Evanston Illinois
A residential sidewalk where green trees provide cooling shade during the summer in the Chicago suburb of Evanston Illinois. James Andrews / Getty Images

It hasn’t been this hot on Earth since before the last Ice Age.

You likely saw the headlines where U.S. scientists declared the average global temperature hit an all-time high on July 3.

Then again on July 4.

And again on July 6.

Unfortunately, climate experts say this series of "World’s Hottest Days" is likely to get another iteration soon, especially as countries around the world continue to experience record-breaking temperatures. The Southwestern U.S., Northern Mexico, parts of Europe, India, and China. Millions of people, all stuck beneath a thick layer of burdensome heat.

These heat waves—which feel more enduring than temporary—can be deadly. The Centers for Disease Control estimates about 700 people in the U.S. are killed by extreme heat every year. Globally, researchers believe the number of heat-related casualties has climbed past 356,000.

In order to save lives, we need a reprieve, and we need it fast.

We need to, in part, turn to trees.

Acting as nature’s air conditioner, a tree can help reduce temperatures by up to 10 degrees Fahrenheit. That seemingly incremental amount can make an enormous difference in the context of human health. For example, if you’re outside in 95-degree weather with 100% humidity, your body’s natural ability to cool itself stops functioning, and your core temp rises. That’s when heat exceeds "uncomfortable" and becomes life-threatening. Even in dry conditions with lower rates of humidity, humans can only handle so much heat. But by expanding the protective canopies of trees in our communities, we can help keep people safe.

Trees can help reduce the risk of heat-related illness and, in some cases, save lives.

This is especially true in our world’s cities. The large concentrations of pavement and buildings absorb heat, forming what’s known as an urban heat island. Trees can help break through these bubbles of high temperatures by shading the ground and lowering surface temperatures.

NYC Skyline Sunset
Jack Berman / Getty Images

Extreme heat also creates other health risks. Inordinately high temperatures diminish air quality and increase ground-level ozone and particulate pollution. Exposure to those conditions can worsen chronic heart and respiratory health issues. The correlation has been repeatedly observed within communities of color and low-income neighborhoods where people are disproportionately exposed to extreme heat and poor air quality. But trees have the power to mitigate these effects. In one study, researchers found children in areas with higher tree density experienced a lower prevalence of childhood asthma.

While El Niño is certainly playing a major role in the extreme heat of this summer, experts say climate change is undoubtedly a factor. Our world is warming up dangerously fast. It’s an unfortunate reality, but it’s not unalterable. The stakes are high. This moment should not be met with inaction. We can help cool off our world’s hot spots.

Trees can be humanity’s shield against grueling heat and the effects of climate change.

Thriving forests in both urban and rural settings help establish a living barrier, designed to keep us safe. It lifts not only the burden of the heat but the burden of worry for the future. Hope is woven in the roots of trees. By planting and caring for them, we can breathe cleaner air. We can foster healthier homes and save lives in every corner of the planet.

We can help ensure the World’s Hottest Day doesn’t get another sequel.

And it starts with a tree.


Dan Lambe is CEO of the Arbor Day Foundation, the largest nonprofit membership organization dedicated to planting trees. He can be reached at


View Article Sources
  1. Centers for Disease Control and Preventions: Heat and Health Tracker

  2. The Lancet: Health in a world of extreme heat. DOI:

  3. United States EPA: Heat Islands and Inequality