How trees create oxygen

How Do Trees Make Oxygen and Improve the Environment?

You don’t have to be an environmental enthusiast to know how beneficial trees are for the environment. Every high school science class speaks about the critical role played by trees in the production of oxygen. Needless to say, planting a tree in your yard and motivating others to grow trees is one of the best things you can do as a responsible citizen of the planet.

But have you ever wondered how trees make oxygen? This article breaks down the scientific process and also looks at the various ways in which trees improve the environment.

Photosynthesis: The Most Valuable Chemical Reaction in the World

Every living organism on earth needs photosynthesis to receive oxygen. In simple terms, photosynthesis is defined as a process where green leaves take in carbon dioxide and water available in the air and the soil and utilize sunlight to convert these compounds into their food, which is sugar. Oxygen, a by-product of the reaction, is released by the leaves back into the air. It’s estimated that photosynthesis carried out by a single large tree is sufficient to provide a day’s oxygen supply for up to four people.

But photosynthesis cannot be carried out by other parts of a plant or a tree, such as the stem or the roots. Chloroplasts of the leaves are responsible for conducting photosynthesis, as they contain chlorophyll. Chlorophyll is a photosynthetic pigment that gives leaves a green color. It also traps the energy from sunlight and converts it into sugar molecules while releasing oxygen.

While there is complex chemistry behind photosynthesis, one can look at photosynthesis as a two-step reaction:

1. Light-Dependent Reactions

As the name suggests, these reactions depend on sunlight. In other words, this is the reaction where light energy is converted into chemical energy.

To the naked eye, sunlight may just appear to be just a source of bright light. But in reality, the rays contain electromagnetic radiation. This radiation also has a specific wavelength, which is absorbed by the green pigments in plants and trees.

When the reaction starts, the pigments capture a certain quantity of light energy, called a photon, at a given time. When the photon reaches the chlorophyll, it reacts with the electron present in the chlorophyll. Chlorophyll also converts the light energy into ATP and NADPH molecules.

As the chlorophyll molecule loses the electron, a water molecule is split to compensate for the loss. This releases oxygen in the membrane-bound compartments of the leaves. Tiny openings on the leaves, called stomata, help to release the oxygen molecules into the atmosphere. All living organisms use oxygen for cellular respiration. They breathe out carbon dioxide, which is in turn absorbed by the leaves from the air.

You may have noticed that the leaves of certain trees start losing their green color during the fall and winter seasons. Such trees are incapable of carrying out photosynthesis. However, the green stems of deciduous trees can perform the same action provided the temperature is warm enough. Interestingly, such stems utilize the carbon dioxide produced by the tree itself instead of absorbing it from the air.

2. Light-Independent Reactions

These reactions do not require the presence of sunlight. The primary goal is to harness the energy from the ATP and NADPH molecules to produce carbohydrate molecules from carbon dioxide absorbed from the air. The carbohydrate molecules serve as food for trees and plants.

How Do Trees Improve the Environment?

Apart from producing oxygen, which is vital for the survival of life, there are several other ways in which trees improve the environment. These include:
Trees help in the conservation of energy by reducing air conditioning requirements by up to 50 percent. Apart from helping you save on your utility bills, they also reduce the emission of harmful gases and protect the environment.

  • The leaves of trees can trap various poisonous gases, such as nitrogen oxides, ammonia, and sulfur. This serves as a natural detox for the environment and keeps it clean.
    The openings on the surface of leaves help to release water vapor into the air and produce a cooling effect. As a result, trees planted on streets can bring down the temperature of your surroundings.
  • Trees are the most effective tool in our fight against climate change. In fact, just an acre of trees can absorb the same amount of carbon dioxide that is produced when you drive a car for 26,000 miles.
  • Trees reduce flooding risks and prevent soil erosion.
  • They provide shade to animals, birds, and human beings.
  • The leaves on the trees also carry out a process called transpiration. This results in the release of water molecules in the air and helps in maintaining the optimum atmospheric moisture levels.

Plant Your Own Tree

Now that you have learned about how trees make oxygen and the multitude of benefits trees offer, are you also keen to plant trees in your yard or garden? Planting a tree is a great investment, provided you’re careful about your choice. Not all trees are created equal, so choosing a species that can thrive in your environment is essential. So before you start digging holes to give a home to a new tree, reach out to an arborist to discuss your options. They will consider several factors, including the soil type and hardiness, proximity to underground pipes, location of electric lines, and so forth before recommending a tree that suits your needs.

You can also get in touch with our team at Mr. Tree Services in Portland, Oregon. We’ll be happy to talk with you and discuss what kind of trees you can consider. Once your trees mature, you’ll also need to schedule periodic pruning sessions to keep them in shipshape. We have a team of professionals that carries out methodical pruning to remove dead or decaying branches. No matter what you need, you can rely on us when it comes to caring for your trees. We’d love to help you.


How Do Trees Produce Oxygen?

Most people are aware of the fact that trees produce oxygen. It’s something we’re told from a very young age, perhaps something we learn in school. Yet the actual process of this oxygen production may well still be a mystery to many people. Knowing more about how trees produce oxygen could be the catalyst to giving them more protection, which would help the planet breathe, so it’s crucial that as many people as possible understand more about what trees do for us, over and above looking pretty and making paper. Since oxygen is what sustains all life on earth, without trees, this planet will die.

Although every living thing on the earth enjoys the benefits of the oxygen produced by photosynthesis, that is not the main reason for the reaction to take place. Since oxygen is not the primary purpose of photosynthesis and is actually simply a side effect of the process, why does photosynthesis occur? The answer is that this is the tree’s way of producing its own food. It does this to live. It’s that simple and that complex. Read on for more details.

The Process Of Photosynthesis

Photosynthesis is the process that turns carbon dioxide into oxygen. The word is Greek, and it translates to ‘light’ and ‘put together’. During this process the tree will combine (put together) the light from the sun, water, and carbon dioxide gas to produce oxygen.

For photosynthesis to work correctly, the first step has to be light. For the tree, this means being able to harness the sun’s energy. To do this, the chlorophyll found within the chloroplasts (cells) of the tree has to absorb the energy from the light of the sun. This is why most trees need to grow in areas with plenty of sunshine. Of course, there are some trees that can manage very well with little light, and some plants even prefer the shade, but each of them will still need at least some sunlight; if you were to put any tree or plant into an entirely dark room, it wouldn’t survive.

The chloroplasts can be seen as tiny storage units for the sun’s energy, keeping it within the tree’s cells after the chlorophyll has absorbed it. This means that even when there is no sun, the tree can continue to grow and produce oxygen as a byproduct of that growth.

The next step in photosynthesis is water. This is where the tree’s roots get to work. They absorb moisture from the ground around the tree, most commonly from rain unless the trees are watered, which might be the case if they are grown in an artificial environment. The tree is able to split the water into its component parts, namely oxygen and hydrogen. Since it can’t use the oxygen, it releases it into the air and in turn, it is breathed in by the earth’s animals, including humans.

Finally, carbon dioxide – the byproduct of oxygen and something that all animal life exhales – is required. By combining the carbon dioxide, hydrogen, and sunlight together, the plant can feed. This process also produces excess oxygen which again releases into the atmosphere.

It’s clear that trees need the earth’s population just as much as the earth needs trees; it’s a symbiotic relationship, especially when you consider that one tree can produce enough oxygen for 10 people to breathe for a year.

Threats To Tree Photosynthesis

Removing one or two trees because they could cause a danger to life or damage a building is often necessary. When we do this, we ensure that we don’t destroy any other trees in the area, and we work to the highest standards.

The same cannot be said for the companies destroying vast swathes of the earth’s tree population. Deforestation is such a big problem that we now only have around 30 percent of the earth’s landmass covered in trees. The deforestation work is removing areas of forest the size of Panama every year. It’s a horrifying thought, and when you put it into focus, it means that in just a century, all the world’s rain forests will be gone.

What does this mean for the planet? One of the effects that scientists are concerned about is the contribution deforestation is making to global warming. Without as many trees to absorb the carbon dioxide that humans and other animals are producing, it will rise into the atmosphere and contribute to the global warming crisis we are battling so hard against. On top of that, the fact that there are fewer trees but more people means that, eventually, oxygen could well become a commodity just like water and electricity. This hardly bears thinking about; imagine having to pay for the air you need to breathe.

One way to limit the issues that deforestation is causing is to plant more trees in other areas. Many environmentalists and geologists feel that this has to be the top priority for all governments. Even though the world is planting around five billion trees every year, deforestation removes approximately 15 billion, which means there is still an imbalance. Once we restore that balance, the planet can be healthier once more.

What Can Affect The Rate Of Photosynthesis?

Photosynthesis is not an easy process to measure; for some trees, it takes place quickly, allowing even those that are seemingly on the brink of death to revive themselves. For others, it all takes much longer so that trees that were otherwise healthy can die quickly if there is even a short period of extremely dry weather, for example, or in arid landscapes. In some cases, these differences can come about due to the tree’s age, overall health, and what species it is, but there are other factors. What is it exactly that can affect the rate of photosynthesis?

Light Intensity and Temperature

As we’ve mentioned, one of the most important elements that goes into the process of photosynthesis is light. The tree has to harvest sunlight and store it within the chlorophyll of the leaves. Scientists have carefully studied how different light saturation levels, light intensity, and temperature can affect the rate of photosynthesis.

The studies discovered that temperature and light were two distinctly different issues. The heat, or otherwise, barely had any effect on the tree itself, whereas the amount and strength of the light has a considerable impact. The more intense the light is that the chlorophyll can capture, the faster photosynthesis can occur (assuming that all other elements are also in place, of course). This could be the reason that some trees thrive in the warmer months and lose their leaves, effectively going into a state of hibernation in which they can survive on much weaker light in the winter.

Carbon Dioxide

Another of the main components needed for photosynthesis to occur is carbon dioxide. As might be expected, the levels of carbon dioxide that a tree can absorb will affect the rate of photosynthesis.

Since the 19th century, the amount of carbon dioxide in the atmosphere has increased thanks to various production methods, the burning of fossil fuels, and even deforestation. In 1860, the atmospheric level of carbon dioxide was 0.028 percent; in 2020, scientists measured it at 0.041 percent. This means that trees are generally able to absorb more carbon dioxide and increase the rate of photosynthesis, thus producing more oxygen. At least, that’s the theory. However, trees are only able to use a certain amount of carbon dioxide depending on their size, species, and the amount of light and water they are absorbing at the same time. In some cases, the tree releases the absorbed carbon dioxide again, unused.


The amount of water needed for successful photosynthesis is only small. However, much larger amounts are required for the release of oxygen to happen. Stomata are tiny holes within the leaves, and the oxygen escapes through these holes when they evaporate water. If there is not enough water to transport all the waste to the leaves, the process of photosynthesis will produce much less oxygen.

Therefore, although lack of water is not necessarily a limiting factor when it comes to photosynthesis, it can certainly be an issue when it comes to the production of oxygen.


The way that trees produce oxygen can often be surprising to those who weren’t aware of the fact or those who thought that trees made oxygen for a purpose, rather than being a byproduct of their own growth and feeding. Yet once you do understand it, you can also understand just how vital trees are for the planet.

Once you then go on to realise that oxygen isn’t the only benefit that trees can offer the human race, it becomes even more interesting. There is so much to learn about trees, and so much they have to teach us; the more we know, the better life can be.

1 How Do Trees Produce Oxygen?

You have been deceived! Trees are not the lungs of the planet - Teletype

We all love plants very much, especially trees. When something is cut down somewhere, a forest, a park or an alley is destroyed, people are indignant, they say that they will have nothing to breathe, that trees are the lungs of the city (and the planet).

In fact, this is a delusion, because although trees emit oxygen, it is not enough for their contribution to the composition of the earth's atmosphere to be tangible. In addition, in the process of life, they themselves absorb this oxygen.

Let's look at how trees actually do with oxygen, using the example of large forests - say, the forests of the Amazon.

In August 2019, when the Amazon rainforest burned, all the newspapers, politicians, celebrities and public figures replicated the same fact: Brazilian forests produce 20% of all oxygen. Someone even considered these fires a threat to life on the planet.

In reality, the contribution of the Amazon to the volume of world oxygen is quite small. According to a 2010 study, all of the Earth's rainforests are responsible for producing 34% of the oxygen produced on land. The Amazon accounts for just under half of these forests and generates about 16% of the oxygen on land, says environmentalist Jadwinder Mali of Oxford University's Institute for Environmental Change.

If we take into account the oxygen produced by phytoplankton in the ocean, the proportion of Brazil's tropical forests drops to 6-9%.

But that's not all. At night, when photosynthesis does not occur, vile trees begin to absorb the oxygen received during the day and release carbon dioxide. This is called cellular respiration. Mali and his research team believe that trees use up just over half of the oxygen they produce. The rest is spent by tropical microorganisms to decompose dead trees and other organic matter.

As a result, the contribution of the Amazon forests or any other biome to the volume of terrestrial oxygen is about 0%, the British scientist is sure.

Colorado State University atmospheric scientist Scott Denning says the oxygen we breathe comes from oceanic phytoplankton that have accumulated this gas for billions of years. Oxygen was not lost due to the fact that huge masses of plankton accumulated at the bottom of the seas before microbes reached them. Otherwise, all the oxygen would be used up in the decomposition of dead organisms. According to Denning, the processes that determine the amount of oxygen in the atmosphere occur over long geological periods and are not affected by photosynthesis.

Nevertheless, forests are very important for the cooling of the planet, which is precisely due to the extraction of carbon dioxide from the atmosphere. Therefore, scientists compare them not with lungs, but with a giant air conditioner that mitigates the effects of climate change on Earth.

Thus, globally, trees do not affect the amount of oxygen in any way. The same applies to our cities. If there are no trees in the city, no parks and alleys, the amount of oxygen will not change. But no one canceled the role of the air conditioner. Trees cool the city, not only by absorbing carbon dioxide, but simply by providing shade. As a result, the temperature on streets with trees is much lower than on streets without trees:

It is comfortable to walk under the trees. Plants and greenery also perform a psychotherapeutic function, because a person came out of the forest, and it is much more pleasant for him to be among trees than among concrete boxes. These are our primitive instincts, so we strive to add greenery to our home, we want to plant something in our yard. A green city is, first of all, comfort. There should be as many trees in the city as possible! But they are not specifically responsible for oxygen.


How the oceans save the Earth from overheating

In the next issue of RBC Trends Green Podcast, we talk about how the oceans give us oxygen, and we repay them with plastic waste

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Surely everyone has heard at least once that forests are the “lungs of the planet”, because they produce oxygen and absorb carbon dioxide. In fact, the world's oceans play a leading role in supplying us with oxygen and absorbing carbon. Trees and plants produce only 20% oxygen. The remaining 80% we get from the ocean. More precisely, thanks to the phytoplankton that lives in the ocean.

It is due to the work of phytoplankton and the ocean ecosystem as a whole that the Earth's atmosphere does not heat up too quickly. But humanity, with its oil production, uncontrolled fishing and plastic pollution, is gradually destroying the ocean.

Podcast host — Anastasia Chizhevskaya, founder of the environmental education bureau Sustainble and blogger.

Conversation timeline

0:17 — How forests take in carbon and release oxygen

03:43 — Why forests are still important

05:41 — How the ocean “breathes”

07:55 — What the oceans suffer from

13:01 — What can be done to save the ocean

Let's talk about forests first

Trees absorb carbon dioxide from the air, because they need carbon to grow. With the help of solar energy, they turn carbon dioxide and water into nutrients, and release oxygen into the atmosphere. On average, for the life of one cubic meter of a tree, about 1 ton of carbon dioxide is needed. As a result of photosynthesis, 700 kg of oxygen enters the atmosphere from this amount of carbon dioxide.

Large tracts of wild forest from 50,000 hectares, in which logging is not carried out, are called "carbon cans". These are, first of all, tropical forests in South America, Africa, Southeast Asia, taiga forests in Russia and Canada. According to Greenpeace, the Amazon forests store between 80 billion and 120 billion tons of carbon. This is a volume equal to 12 years of global emissions.

If we start building roads, cutting trees and mining in such forests, a huge amount of carbon will be released. In addition, as a result of forest fires, the forest turns from a carbon dioxide absorber into its source.

At night, photosynthesis does not occur, and trees consume oxygen. Animals, fungi and bacteria that live in the forest and do not produce oxygen themselves also need to breathe. Also, the forest spends oxygen from the atmosphere on the decomposition of the remains of dead organisms. As a result, forests work as if "to zero", absorbing about the same amount of oxygen as they emit.

How the ocean "breathes"

The ocean absorbs carbon from the surface and stores it in deep waters. It takes about 30% of the carbon emissions that people produce. If not for the oceans, the planet would quickly become too hot for life.

In seawater, carbon molecules are converted into other chemical compounds or serve as food for phytoplankton - single-celled algae and cyanobacteria. Molecules eaten by phytoplankton are separated into oxygen and carbon. Oxygen returns to the water, and carbon accumulates in the growing phytoplankton.

If the ocean stops absorbing and retaining carbon, it will be impossible to slow down global warming.

What is happening to the ocean

According to the UN, already 40% of the world's oceans have been severely affected by human actions . There are two reasons - pollution and depletion of fish stocks.

What pollutes the ocean:

  • oil and oil products;
  • waste water from enterprises where there are heavy metals, mercury and other hazardous substances;
  • agricultural pesticides;
  • plastic waste and lost fishing nets.

It is believed that every minute a truckload of plastic enters the sea. If this continues, by 2050 there will be more plastic in the ocean than fish.

According to the Whale Protection Fund, more than 2.5 thousand dolphins have died in the Black Sea over the past five years due to human actions.

Uncontrolled fishing also causes harm. Overfishing disturbs the natural balance in the ocean ecosystem. In addition, Commercial fishing is generally very inhumane. For example, when trawling, in addition to fish, marine mammals also get into the net, which are of no nutritional value, but still die in the nets. In addition, some countries, such as Japan, still allow whaling.

According to the UN, today 90% of large fish populations are depleted and 50% of coral reefs are destroyed .

Another problem in the ocean is water acidification. Carbon released into the atmosphere dissolves in sea water and turns into carbonic acid, which makes the water more acidic. Acidification, directly or indirectly through the food chain, affects all ocean life. If the level of water acidification reaches the level at which phytoplankton begins to die, this will acidify the environment even more. This could destroy the entire ocean.

Sunscreens containing oxybenzone are also harmful to corals and other marine life.

What can be done to save the ocean