Canopy Tree Project
5 Reasons We Need Trees for a Healthy Planet
September 15, 2025
Updated September 15, 2025
In the past 10,000 years, we’ve lost 33% of the world’s forests. And today, with our sprawling urban areas and wide open fields, it’s tough to envision what a truly wooded world once looked like.
In 2024 alone, we lost 26.8 million hectares of natural forest to deforestation, logging and fires. Climate change doesn’t help matters: Research findings from 2022 suggest that deforestation, alongside rising temperatures, is transforming what’s left of our forests, keeping trees smaller and younger.
To ensure a safe, healthy future, we must restore these forest habitats. Here are five reasons we need trees.
1. Trees purify our air and combat climate change
Forests are carbon sinks that help slow climate change by removing carbon from the atmosphere and storing it in trunks and soil. In particular, old-growth forests — forests containing trees that have reached old age without major human disturbances such as logging — hold much larger amounts of carbon and harmful pollutants than their younger counterparts. And yet, only 24% of old-growth forests on Forest Service and Bureau of Land Management lands in the United States are unprotected from logging.
Trees absorb approximately 30% of global emissions every year and when we burn them or cut them down, all of that pollution gets released into the air. A recent study found that between 1999 and 2020, the global carbon sink in established forests has declined due to climate change, while another study estimated that between 2010 and 2050, global forest loss will result in 3.5 to 4.2 billion metric tons of greenhouse gasses entering the atmosphere each year. Even small amounts of air pollution contribute to a plethora of health issues that affect society unevenly.
2. Trees provide housing to millions of species that protect us from disease
It is estimated that nearly 50 percent of Earth’s terrestrial biodiversity resides in rainforests and as of 2023, we also know that there are around one million species worldwide at risk of extinction.
A quarter of our medicine comes from plants found in the rainforest, yet only 5% of plant species in the Amazon — the world’s largest rainforest — have been tested for medicinal benefits. There may be several medicinal properties still yet to be discovered from within these tropical forests, but as we continue to encroach on and destroy forest habitats, we will lose these valuable species and create bigger threats.
Already, three out of every four new infectious diseases in people come from animals, and this number will only increase as humans encroach further into wildlife habitats. However, studies show that high levels of biodiversity within ecosystems can have a “dilution effect” on disease within hosts, making diseases less likely to jump to humans.
In other words, protecting forest habitats and the biodiversity of species that live within them could prevent the next pandemic.
3. Trees cool our streets and cities
2024 was the hottest year on record, with 2025 looking to close in a tight second place.
Trees, however, cool the Earth by blocking sunlight and providing shade — in fact, air temperature under trees can be up to 25°F cooler than surrounding air. The natural shade that canopies provide can also reduce energy use for indoor cooling and heating. The U.S. Department of Energy states that planting trees around your house can reduce solar heat gain from windows and roofs, thus reducing costs for air conditioning.
Trees also help control climate through evapotranspiration — a process where water is drawn up through the soil by the roots and evaporates from the leaves. The surrounding air cools as heat from the air is used to transform the water to vapor. One tree can transpire hundreds of liters of water per day, representing a cooling power equivalent to two average household air-conditioning units per day.
To combat the heating effects of concrete in cities, studies suggest canopy coverage of 40 percent or higher on city blocks in order to generate the greatest cooling effect. With over half of the world’s population living in cities — notoriously hotter because of concrete, poorer air quality, limited shade and green space, buildings — we must try all we can to beat the heat.
4. Trees protect against floods and water pollution
Mature trees protect communities against flash floods and landslides by stabilizing soil and absorbing water — reducing surface water run-off 80% more than asphalt. Through their powerful roots, trees prevent approximately 400 billion gallons of runoff each year in the United States.
Tree roots also filter harmful chemicals and pollutants from storm runoff that ends up in lakes, streams and rivers. Forests provide drinking water to more than 150 million people in the United States, according to the U.S. Forest Service.
Or, put simply: more trees = cleaner water.
5. Trees ease the mind during stressful times
If we continue to destroy the environment, we’ll be living in very stressful conditions: droughts, massive storms, pandemics, floods. But trees have a double effect on society: fighting climate change while relieving stress.
Trees in rural and especially urban areas benefit our mental and physical wellbeing. Studies show that urban trees result in better health outcomes for local communities, including improved cardiovascular function, thermal comfort, and reduced anxiety. Spending just a few minutes outdoors can reduce blood pressure, relieve stress and build a stronger immune system. But there are even benefits from viewing nature out the window, such as increased job satisfaction, as one study in the South Korean capital of Seoul found – home to 9.6 million people.
It’s going to take more than reforestation
Investing in reforestation (like through EARTHDAY.ORG’s The Canopy Tree Project can certainly help slow climate change, and provide many benefits to both humans and the environment in the short term and the long term. Planting forests is a critically important way to take action on behalf of Our Power, Our Planet.
But while planting trees is important, we must also address the underlying issues of air and water pollution, the burning of fossil fuels, and the impact of mass consumption which are all part of the climate change disaster. In addition to championing trees, please sign our Plastic Petition to force the governments of the world to fight plastic production and pollution. Think about buying less and rejecting Fast Fashion. Work your Green Muscle Memory so that you make Earth-friendly decisions every single day.
