Trees are vital to our ecosystem.

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Often known as the ‘lungs of the Earth’, they play a key role in storing carbon dioxide and producing oxygen. In addition, they are key to stabilising soil, and reducing air temperature, humidity, and flooding. As such, protecting, preserving and planting trees represents a real opportunity for carbon footprint compensation.

The tree: A carbon sink

Global warming is an urgent problem we need to tackle. The main cause is the increasing concentration of greenhouse gases in the atmosphere. Thanks to their ability to absorb carbon and produce oxygen, protecting trees is probably the best way to stop this global phenomenon.

Photosynthesis of plants: A summary

Trees are known as ‘carbon sinks’ because of their ability to store carbon. This is done through a process called photosynthesis. Trees absorb carbon dioxide through their leaves and turn them into sugars needed for them to grow. As the tree grows, it is able to lock away the carbon in its branches, roots and trunk, playing a key role in combating the effects of global warming.

What is a carbon sink?A carbon sink is a natural reservoir that captures and stores carbon from the atmosphere. There are several types of sinks: oceans, forests, and agricultural land. After the oceans, forests are the second largest carbon sink on the planet.

Reforestation: A way to reduce the impact of the greenhouse effect

Reforestation is one of the best ways to absorb carbon dioxide from the atmosphere and counteract global warming.

Deforestation is one of the main causes of biodiversity loss, another great challenge we face in the 21st century, and of climate change. Reforestation is one of the key ways to combat it. Trees play an essential role in the balance of the ecosystem. They serve as a habitat for many species of animals, birds and insects.

Trees contribute to mitigating the effects of climate change in several ways:

Carbon sequestration by forests.
Carbon storage in forest soils or in processed wood products through photosynthesis.
The substitution of fossil fuels for the use of wood as an energy source.
The replacement of energy-intensive materials such as aluminum or PVC.

Trees are easy to plant, they remove CO2 from the atmosphere accumulated over years and absorb it over a long period. In addition to absorbing CO2, they emit oxygen.

When burning, trees release all the CO2 they have absorbed, which is why it is necessary to prevent forest fires.

The carbon footprint in the forestry sector

There are a number of projects across the UK and in other countries around the world that aim to plant trees, preserve and protect forests - so vital for the absorption of carbon dioxide. By supporting these organisations, such as the Woodland Trust or the National Forest, you can help offset your carbon emissions.

According to a Swiss study, 1.2 billion trees would have to be planted on Earth to absorb two-thirds of the CO2 produced by man since the industrial age.

However, although reforestation helps in the fight against global warming, it is important, in addition to offsetting its CO2 emissions, to try to reduce them beforehand.

Any approach to carbon offsetting must be preceded by actions to reduce your carbon footprint. This can be done various ways by making changes in your day-to-day life such as:

Switching to a green energy provider.
Avoid using the car for short journeys and choose to walk or cycle instead. For longer journeys, think about using public transport such as busses or trains.
Reduce the amount of meat you consume.
Adopt a more environmentally sustainable lifestyle.

Planting trees to tackle climate change

The benefits of a tree for the planet as a carbon sink seem obvious. But how much do they reduce air pollution?

It is important to distinguish between air pollution and greenhouse gases. Both are responsible for climate change, however, atmospheric pollutants (carbon monoxide, nitrogen oxides) usually have negative effects on health, while greenhouse gases, such as carbon dioxide, do not necessarily have a direct impact on health.

Carbon sequestration: What is the CO2 absorption capacity of trees?

In the UK, a person emits an average of 7.01 tons of CO2 per year. This varies greatly depending on the lifestyle of each person (food, transport, housing, etc.).

Although the carbon absorption capacity can vary, it is generally considered that a tree can store about 167 kg of CO2 per year, or 1 ton of CO2 per year for 6 mature trees. This means that more than 67 trees would have to be planted a year to offset the CO2 emissions of a single Brit.

What species absorb the most CO2?

Not all trees are equally eco-efficient. The carbon absorption capacity varies greatly from tree to tree, even those of the same species. There are many factors to be considered, including:

The species
Age
Size
The weather conditions
The type of soil

Some trees grow more quickly than others and therefore absorb CO2 faster, as is the case with the eucalyptus. In contrast, other tree species grow slower but also live longer and therefore absorb more CO2 over the long term, such as oak or beech. It is difficult to estimate which trees absorb the most CO2.

To calculate this average, the composition of the forest must be taken into account. Forests with a variety of species (mixed forests) should be favoured because they absorb more CO2.

Fever Tree

A tree absorbs approximately 25kg of CO2 per year

We cheated and gave you the short answer first! It's based on the estimate that a cubic metre of wood absorbs just under a ton of CO2.

But really a tree absorbs anywhere between 10 and 40kg of CO2 per year on average, depending on a whole host of factors. And it's all those complex variables that make working out how much CO2 a tree absorbs so interesting. So let's start breaking it down. For fun!

A little word about calculating CO2 before we start

We've developed our own scientific methodology to calculate the average absorption of our trees, verified by Bureau Veritas. We've done it to help you quantify your contribution towards global carbon neutrality and go on a bit about this in our Carbon Manifesto. But now that's said, let's get to it!

The chemical composition of wood

The chemical composition of wood doesn't vary much from tree to tree. (Hooray, one thing that doesn't change massively in all this!)

Cellulose (C6H10O5)n is the main component of the cell walls of trees. It's a chain of glucose molecules that the tree produces through photosynthesis. We'll look at how in a minute. Cellulose makes up 50-80% of wood.

50% carbon

42% oxygen

6% hydrogen

1% nitrogen

1% mineral matter

Photosynthesis is really cool
Photo From the Greek for « Light »
Synthesis Greek for « Putting together »

Step 1

Plants absorb water and minerals through their roots to make sap.

Step 2

The sap travels through the tree to the leaves. The leaves absorb CO2 and light.

Step 3

The leaves use chlorophyll and the sun's energy to convert CO2 & water into glucose.

Step 4

Oxygen is released and the glucose nourishes the tree, transported by the sap.

Purifying the air as it grows
Amazingly, to grow by one cubic metre, a tree will purify nearly one million cubic metres of air of its CO2 (assuming 0.03 to 0.04% of air is CO2).1 Trees are the best.

How much water is there in a tree?

Depends! Mostly on the species of the tree, but also on the humidity of the air influenced by season and location. Trees contain three types of water; bound water in fibres, free water that’s released when they dry, and water of constitution that’s part of their molecular structure. 50% of a tree’s weight is water. But the moisture content of different living tree species can range from.

How to calculate the carbon in a tree

Now we know how much of a tree is water, we need to remove that from the equation. Because to calculate the carbon content of a tree, we need to know its dry mass. That’s its mass excluding the water.

Dry mass: 50% of the tree is the dry mass

Carbon: 47.5% of the dry matter of the tree consists of carbon³

Water: 50% of the tree is water (20% of that in the roots)

Now let’s work out how much CO₂ a tree absorbs

To do it, let’s use an example. We’ll imagine a 1000kg tree with 100% humidity. Now we know this tree is 500kg water and 500kg dry mass. And we know that 47.5% of that dry mass is carbon. That’s 237.5kg.

Thanks to molar mass ratios, we can break CO₂ down and find that it takes 3.67kg of CO₂ to create 1kg of carbon in the tree. That’s because carbon has a molar mass of 12 and oxygen 16. Combined as CO₂ that’s 44. And 44/12 = 3.67.

So for our tree example, 237.5 × 3.67 = 871.63kg of CO₂. Hooray! If we want to know how much it’s absorbed per year, we need to know the age. If it weighs a ton standing, we can guess it’s 30 to 40 years old. So if we assume it's 35 years old, this big boy absorbed 25kg of CO₂ per year.

How the species of the tree affects CO₂ absorption

First off, the carbon storage capacity of a tree depends on its species, as their mass varies. You can really see that in these examples: Poplar (400kg/m³), Weymouth Pine (1000kg/m³) and Ebony (1400kg/m³). So this needs to be taken into account in any calculation.

All our trees are great at absorbing CO₂!

So our calculations are based on plausible estimates, averages and variations like soil, light, age and climate. But in the end, even though they absorb carbon dioxide at different rates and in different amounts, they’re all doing it! And it just shows the importance of mixing tree species and ages in a forest specifically adapted to its environment. This is the best way to reduce our carbon footprint and limit the impact of climate change. And it’s what we do with your trees in our EcoTree forests.

When do trees absorb most CO₂?

Young trees or old trees? That is the question scientists are still debating. In their youth, trees grow faster so they absorb CO₂ quicker, but in their old age their density is much greater so they can absorb more CO₂, as this 2014 study in Nature demonstrates. As for our trees, the ones below will give you the most bang for your buck when it comes to CO₂ absorbed over their lifetimes.

tree absorbs about 25 kg of C0₂ anually.

Our carbon capture calculations have been verified by world-renowned Bureau Veritas. So when you own a tree, you can track the carbon captured over its whole lifetime!

In the end, most of the figures put forward should be taken with great care, but they give an average range of 10 to 40kg of CO₂ absorbed per tree per year over a lifetime.