How Do Trees Absorb Carbon & How Much?

1. How Trees Absorb Carbon

Trees play a key role in reducing carbon dioxide (CO₂) in the atmosphere. They act as natural carbon storage systems, pulling CO₂ from the air and storing it in their roots, trunks, and leaves.

How It Works

• Trees absorb CO₂ during photosynthesis.
• They use sunlight to convert CO₂ into oxygen and glucose.
• Oxygen is released back into the air.
• Glucose provides energy for growth and is stored as starch in the tree’s trunk, branches, and roots.
• Stored carbon remains inside the tree, building its structure over time.

Where the Carbon Goes

• Leaves and branches hold some carbon while the tree is growing.
• Trunks and roots store most of the carbon over the tree’s lifetime.
• Soil absorbs carbon when leaves and roots break down.

Why Some Trees Absorb More Carbon

• Fast-growing trees like poplar and eucalyptus absorb CO₂ quickly but store less over time.
• Slow-growing hardwoods like oak and beech absorb less each year but store more in the long run.
• Older trees store more carbon but take longer to reach that stage.

2. How Much CO₂ Does a Tree Absorb Per Year?

The amount of CO₂ a tree absorbs depends on its species, age, and location.

Average Absorption Rates

• A young tree absorbs less CO₂ as it focuses on growing.
• It is said that a mature tree absorbs about 22 kg (48 lbs) of CO₂ per year on average however this depends heavily on the type of tree and where it is planted.
• Some fast-growing species absorb more in the first 20 years but level off later.

Comparing Different Trees

• Oak (Hardwood) – Absorbs CO₂ slowly but stores large amounts for centuries.
• Pine (Softwood) – Absorbs CO₂ faster but doesn’t store as much long term.
• Mangroves – Capture more CO₂ than most land trees due to their dense root systems.

The Environment Matters

• Trees in tropical climates absorb CO₂ year-round.
• Trees in cold regions absorb less in winter.
• Trees in polluted areas often grow slower, reducing absorption.

3. How Much Carbon Can Trees Store Over Their Lifetime?

The amount of carbon a tree stores depends on its species, age, and environment.

Typical Trees

• On average, a mature tree absorbs around 22 kg of CO₂ each year.
• Over 50 years, that equals about 1.1 tonnes (1,100 kg) of CO₂ per tree.

Large Trees (like Oak)

• A large oak tree aged around 100 years stores approximately 3 tonnes of CO₂ or more.
• Larger, older trees store significantly more carbon in their trunks, branches, and roots.

Mangroves – Exceptional Carbon Storage

• Mangrove forests store carbon more effectively than other tree species.
• A hectare of mangroves holds roughly 739 tonnes of carbon in total, mostly stored in the soil beneath them.
• Mangroves absorb about 23 tonnes of CO₂ per hectare each year—two to three times more than typical forests.

Dense Forests and Annual Absorption

• Young, fast-growing forests typically absorb between 5 and 40 tonnes of CO₂ per hectare each year.
• Mangrove restorations can absorb approximately 23 tonnes of CO₂ per hectare annually.

Factors That Affect Carbon Storage

• Growth Rate – Faster-growing trees absorb CO₂ quickly but store less long term.
• Lifespan – Older trees hold more carbon, but if they die young, they release CO₂ back sooner.
• Tree Density – Forests store more carbon than scattered trees.

The Bigger Picture

• Old-growth forests store more carbon per hectare than newly planted ones.
• Protecting existing trees is just as important as planting new ones.

4. What Happens to the Carbon After a Tree Dies?

When a tree dies, the carbon it stored doesn’t just disappear. It follows different paths depending on how the tree decomposes or is used.

Decomposition and Carbon Release

• When a tree falls and decays, microorganisms break it down, releasing some stored carbon back into the air as CO₂ and methane.
• The rate of decay depends on climate:
• Hot, humid regions → Faster decomposition, more CO₂ released quickly.
• Cold, dry areas → Slower breakdown, carbon stays locked in longer.
• Trees that fall into wetlands or bogs can hold carbon for thousands of years due to low oxygen levels slowing decomposition.

Carbon Storage in Soil

• Tree roots and fallen leaves add carbon to the soil, where it can remain for centuries.
• Forests store more carbon in their soil than in their trees over time.

Carbon Retention in Wood Products

• If trees are used for furniture or buildings, their carbon remains locked away.
• Well-maintained wooden structures can hold carbon for hundreds of years.

Wildfires and Deforestation

• If a tree burns, most of its stored carbon is released instantly as CO₂.
• Deforestation speeds up this process, making it harder to balance CO₂ levels.

5. Why Planting Trees Alone Isn’t Enough

Planting trees helps absorb CO₂, but it’s not a complete solution. To make a lasting impact, trees need to be protected, managed, and planted strategically.

Challenges of Tree Planting

• New trees absorb CO₂ slowly – It takes years before they store significant amounts.
• Deforestation cancels out progress – If mature trees are lost, planting new ones won’t compensate fast enough.
• Monoculture forests aren’t as effective – Planting just one species can harm biodiversity and reduce carbon storage potential.

How to Make Tree Planting More Effective

• Preserve existing forests – Mature trees hold the most carbon.
• Choose the right species – Native trees support ecosystems and last longer.
• Ensure long-term care – Trees need protection from disease, pests, and deforestation.
• Support soil health – Healthy soil traps carbon for longer.

A Better Approach

• Large-scale forest restoration absorbs more CO₂ than isolated tree planting.
• Community involvement ensures trees are maintained for decades.
• Carbon offset programs help businesses and individuals contribute effectively.

6. The Impact of Trees on Carbon Reduction

Trees play a vital role in reducing CO₂ levels, but their full impact depends on long-term conservation and responsible reforestation.

Key Takeaways

• A mature tree absorbs about 22 kg of CO₂ per year.
• Over its lifetime, a tree can store 500 kg to 3 tonnes of CO₂, depending on its size and species.
• Forests store more carbon than individual trees, with soil holding a large portion.
• When trees die, some carbon is released, but much remains locked in wood, soil, or long-lasting products.
• Protecting forests is just as important as planting new trees to fight climate change.

How You Can Help

• Support reforestation efforts that prioritize biodiversity and long-term care.
• Reduce deforestation by choosing sustainable wood products.
• Offset your carbon footprint by planting and preserving trees through verified programs.

Every tree makes a difference, but a combination of planting, protecting, and restoring forests is the most effective way to reduce CO₂ in the atmosphere.

Support our members at Greener Earth Alliance who are investing in reforestation the right way!