Welcome back to Tree Facts Friday!
I’m ISA Board Certified Master Arborist, Mitch Hoy, with ArborWise Tree Management. This week, we’re diving into an incredible topic: how trees influence climate, not just by providing shade, but through powerful biological processes that regulate temperature, rainfall, and even global carbon levels.
Understanding Evapotranspiration: Nature’s Cooling System
One of the most important processes in how trees affect the atmosphere is evapotranspiration. This is the combined process of soil evaporation and plant transpiration, where water moves from the land to the air. As trees release water vapor through their leaves, the surrounding air cools and gains moisture.
This cycle plays a critical role in regulating:
- Temperature
- Precipitation
- Humidity
- Soil moisture
- Vegetation density
In short, evapotranspiration acts like nature’s air conditioner—moderating local and regional climates while supporting healthy ecosystems.
Photosynthesis: Trees as Climate Champions
Another major player in climate regulation is photosynthesis. During this process, tree leaves absorb carbon dioxide, water, and sunlight to produce sugars for growth, releasing oxygen as a byproduct.
This helps reduce atmospheric carbon dioxide levels, directly supporting global efforts to combat climate change.
However, the impact of photosynthesis on temperature varies:
- Deciduous trees, with their broad leaves, provide endothermic cooling during summer months, absorbing sunlight and releasing water vapor.
- Coniferous trees in northern boreal regions, by contrast, can absorb sunlight in winter with their darker foliage, creating a localized warming effect.
The climate influence of trees depends on factors like species, density, and regional conditions.
Trees as Carbon Sinks: Storing Climate Solutions
According to the National Forest Foundation, a single mature tree can sequester up to half a metric ton of carbon dioxide annually. Collectively, U.S. forests offset about 16% of national greenhouse gas emissions, making them one of the largest natural carbon sinks on Earth.
Forests don’t just store carbon—they shape the weather itself. The exchange of energy, water, and carbon between land and air affects local climate feedbacks. When soil moisture decreases during droughts, evapotranspiration slows down, which can intensify heatwaves and extend dry periods, as described in G. B. Bonan’s research, “Forests and Climate Change: Forcings, Feedbacks, and the Climate Benefits of Forests.”
Air Quality and Energy Efficiency
Trees improve more than just the global atmosphere—they make local air cleaner and cooler. The Potomac Conservancy notes that trees help reduce pollution by filtering particulates and gases.
In urban areas, trees also reduce energy consumption by providing natural cooling. Neighborhoods with dense tree cover experience lower air conditioning costs and more comfortable summer temperatures.
Forests and Rainfall: The Global Water Cycle in Action
Rainforests like the Amazon illustrate trees’ influence on regional weather. Through constant transpiration, these forests release water vapor that fuels rainfall across entire regions.
Conversely, deforestation disrupts this cycle—reducing moisture in the air and leading to drier downstream conditions, as reported by the U.S. Environmental Protection Agency.
Trees also:
- Reduce wind speed and dissipate wind energy, stabilizing weather patterns (ScienceDaily).
- Release organic compounds that help form clouds and increase rainfall.
- Improve percolation, slowing runoff and reducing flooding during storms.
When trees are removed, rainwater flows more quickly into rivers, increasing flood risk and leading to longer, more severe droughts.
The Drought Connection: When Climate Fights Back
Recent studies from the National Science Foundation, led by William Anderegg, Anna Trugman, and David Bowling (University of Utah), found that certain trees actually increase water use during droughts to cool themselves.
While this helps the trees survive heat stress, it can worsen drought conditions by releasing even more water vapor into an already dry atmosphere. This delicate balance shows just how interconnected our ecosystems are.
Unfortunately, human activities—like deforestation, development, and resource extraction—intensify this cycle. When forests disappear, soil dries faster, surface temperatures rise, and precipitation patterns change.
Protecting Forests Protects the Future
Maintaining tree cover isn’t just about scenery—it’s about climate stability. Every tree helps balance moisture, absorb carbon, and protect against extreme weather. The more we preserve and restore forests, the more resilient our environment becomes.
At ArborWise, we promote sustainable urban forestry practices, helping communities maintain strong, healthy trees that benefit both people and the planet.
Join Us in the Tree Movement
Thank you for joining us for another Tree Facts Friday with ArborWise Tree Management!
If you’d like to learn more about how trees influence climate—or how you can protect them—follow us on Facebook, YouTube, and visit our website at arborwisemn.com.
And don’t miss us at this Friday’s Arbor Day Celebration on April 25th in Rochester, MN!
Keep on rockin’ in the tree world!
