What Is the Carbon Cycle?
 
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What Is the Carbon Cycle? Photosynthesis, Decomposition, Respiration and Combustion
LIFE SCIENCE | NATURAL ENVIRONMENT
Updated on May 12, 2022Life Science, Natural Environment
 
Carbon cycles from the atmosphere into plants and living things. For example, carbon is a pollutant in the atmosphere as carbon dioxide.

But it’s also the most important building block for all living things including glucose.

Over millions of years, carbon can get re-purposed into hydrocarbons. This is the long-term carbon cycle.

So, carbon takes up various forms: glucose in plants, carbon dioxide in the air, and hydrocarbons like coal.

But today, we’ll talk about the short-term carbon cycle that just takes days, months, or years for carbon to cycle through the environment.

 
1. Photosynthesis
 
Plants pull carbon dioxide out of the air through photosynthesis. Even though carbon dioxide makes up less than 1% of the atmosphere, it plays a major role for living things.

With CO2 and H2O in the atmosphere, photosynthesis produces sugars like glucose. This is the plant material that plants synthesize on their own.

If you have the right conditions, this process can repeat for centuries. Not only does photosynthesis pulls carbon dioxide out of the atmosphere, but it fuels all living things as a source of energy.

 
2. Decomposition
 
By mostly using sunlight, water, and carbon dioxide, plants can grow. In turn, animals consume food for energy using O2 and giving off CO2. Alternatively, they die, decay, and decompose repeating for millions of years.

Decomposition is the process of breaking down plants. Over vast periods of time, layers of sediment build on each other. Because of the pressure and heat from within the Earth’s crust, it generates fossil fuels. Much of this happened during the Carboniferous Era.

For example, coal, oil, and natural gas (methane) are some of the common fossil fuels. Over the long term, the decomposition of dead matter generates these fossil fuel products.

Anaerobic decomposition involves bacteria breaking down organic matter such as glucose into CO2 and methane (CH4). The nutrient cycle recycles inorganic and organic material in the soil through the process of decomposition. Then, it goes back again through the same process again.

 
3. Respiration
 
You and I are both made of carbon. We consume plants. But we also breathe in the air, which has carbon in the form of carbon dioxide.

Animals rely on plants for food, energy, and oxygen. Our cells require oxygen to break down the food we consume through cellular respiration.

Once consumed, carbon dioxide is released into the atmosphere because of cell respiration. In turn, this CO2 produced from respiring cells can be used in photosynthesis again.

In other words, plants use solar energy to break apart that same carbon dioxide in the air. Through photosynthesis, it uses that same carbon for plant material in turn releasing oxygen again.

 
4. Combustion
 
Our cars use the energy released by burning fossil fuels. And carbon is also a pollutant as carbon dioxide.

We extract fossil fuels, combustion involves burning them to release energy. But a by-product of combustion is that it releases carbon dioxide back into the atmosphere. And too much CO2 increases the greenhouse effect.

Because we deplete our oil reserves by adding CO2 into the air daily, it affects the carbon cycle with an imbalance of oxygen and carbon. Carbon dioxide is one of the greenhouse gases contributing to climate change.

But there is a limit to how much fossil fuels we can extract. Over millions of years, phytoplankton resting on the ocean surface photosynthesizes and takes in CO2.

Using sunlight creates a molecule called glucose (C6H12O6) and sinks to the bottom of the ocean. Humans discovered these fossil fuels beneath the ocean. We started to drill the ancient plankton, which over millions of years ago, became the oil we use today.

 
Long-term carbon cycle summary
 
Today, you’ve learned how carbon cycles from the atmosphere and then into plants and living things. But the distinction between the short-term carbon cycle is that this cycle takes millions of years to come full circle.

Instead of carbon converting into sugars, carbon is re-purposed into fossil fuels like coal. When plants are buried and compacted over millions of years, they become hydrocarbons.

When you drive your gas-powered car, you tap into Earth’s carbon reserves deposited hundreds of million years ago. These fossil fuels are released into the air as carbon dioxide and water vapor.

It may stay in the atmosphere for a while, but eventually, plants consume it during photosynthesis. So that same weight from the tank of gasoline gets converted into wood or plant material by photosynthesis.

 
What Is the Carbon Cycle?
Carbon is a chemical element that is an essential part of all living organisms. It is found in the bodies of plants, animals, and people. Carbon dioxide is constantly being released from burning fossil fuels, plants, and animal respiration. The amount of carbon dioxide in our atmosphere affects global warming.

Do you want to learn more about environmental science and topics like the carbon cycle? Then, check out some of the courses available for you to help advance your career.

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35 Comments
Laiken says:
April 13, 2023 at 3:27 pm
It’s part of our DNA and protein molecules. In fact, it’s the building block of all life on Earth. The carbon cycle is Mother Nature’s way of reusing and spreading the carbon around, releasing it naturally over time. Dead organisms decompose, eventually becoming fossil fuels such as oil and gas trapped underground. It helps to regulate Earth’s temperature. It makes all living life possible. It is a key element in the food that sustains us. It provides a key source of the energy that fuels our economy. Carbon moves from the atmosphere to plants.
Carbon moves from plants to animals.
Carbon moves from plants and animals to soils.
Carbon moves from living things to the atmosphere.
Carbon moves from fossil fuels to the atmosphere when fuels are burned.
Carbon moves from the atmosphere to the oceans.
Laiken says:
April 13, 2023 at 2:59 pm
Carbon fixation is the process by which inorganic carbon from the atmosphere is assimilated into living organisms and converted into organic compounds. These compounds are used to store chemical energy. It is an essential process for the sustainability of life.

Carbon fixation is the process of attaching an inorganic carbon to an organic compound and is an important part of photosynthesis. Carbon fixation is the first step of the Calvin cycle. It involves the enzyme RuBisCO ”fixing” CO2 to RuBP, producing two molecules of 3-PGA.
Laiken says:
April 13, 2023 at 2:55 pm
Photosynthesis is the process through which plants “fix” carbon from gaseous carbon dioxide to produce sugar. Carbon moves from the atmosphere to plants.
Carbon moves from plants to animals.
Carbon moves from plants and animals to soils.
Carbon moves from living things to the atmosphere.
Carbon moves from fossil fuels to the atmosphere when fuels are burned.
Carbon moves from the atmosphere to the oceans. Carbon is a pattern maker. It can link to itself, forming long, resilient chains called polymers. It can also bond with up to four other atoms because of its electron arrangement. Atoms are arranged as a nucleus surrounded by an electron cloud, with electrons zinging around at different distances from the nucleus.
Photosynthesis, burning of fossil fuel, respiration is involved in the carbon cycle, transpiration is not involved in the carbon cycle. Carbon compounds regulate the Earth’s temperature, make up the food that sustains us, and provide energy that fuels our global economy.
It helps to regulate Earth’s temperature. It makes all living life possible. It is a key element in the food that sustains us. It provides a key source of the energy that fuels our economy. Photosynthesis, Decomposition, Respiration and Combustion. Carbon cycles from the atmosphere into plants and living things.
manny says:
April 5, 2023 at 1:48 pm
What about volcanic activity going into the atmosphere?
Dakota Tuttle says:
March 10, 2023 at 8:37 am
Thanks, this helped me a lot
Danielle says:
October 20, 2022 at 5:41 pm
So exactly, how much Carbon is being transferred per year?
Tonny says:
August 6, 2022 at 5:49 am
A very well and precise explanation.
Shell says:
May 6, 2022 at 12:54 pm
Carbon dioxide isn’t a pollutant. It’s plant food. Plants and trees don’t just store carbon dioxide. They absorb carbon dioxide, and then convert it into oxygen for us to breathe. That absorption and conversion is photosynthesis.
Boni Bontosh says:
March 2, 2022 at 2:38 am
Well explained
Giles Jotty says:
January 23, 2022 at 5:15 am
Really helpful article, Thanks to whoever wrote this. It helped me a lot
Chukwu fidelis says:
November 22, 2021 at 1:23 pm
This is nice
Ghans says:
November 7, 2021 at 5:39 am
Can someone explain carbon fixization?
Freddo says:
October 10, 2021 at 4:12 am
The carbon cycle is, and always has been, fundamental to Life on Earth – but only since the dawn of that life – before that it was inconsequential. Should not the effect of electricity, in the form of Lightning, be considered in the carbon cycle?
Samuel Kawunde says:
July 17, 2021 at 5:12 am
Nice explanation
Dubu Luv says:
July 16, 2021 at 12:05 am
Thank you so much for such a clear and concise explanation with nice diagrams. You have helped me understand the complex carbon cycle. Thank you!
Mubarak ali kolwahi says:
June 29, 2021 at 12:34 pm
Well defined briefly that helped me for making my assignment
Sekinnah says:
June 14, 2021 at 6:32 pm
Thanks for helping me this is enough for my assignment thanks a lot.
Gabe says:
May 18, 2021 at 1:18 pm
Hello! My science teacher used this.
Micheal Clark says:
April 11, 2021 at 3:05 am
Carbon facts in trillions of tons:
Atmosphere. 0.85 TT. .0008%
Plants and Soil. 2.00. TT. .0020%
Fossil Fuels. 10.00. TT. .0100%
Oceans. 38.00. TT .0380%
Carbonaceous Rocks. 100,000. TT. 99.9490%
There is currently almost 4 times more CO2 dissolved
Ana Jones says:
April 1, 2021 at 1:41 pm
What even about the volcanic activity that’s even going into our atmosphere?
Gift says:
January 28, 2021 at 11:59 am
Leaving a comment…thanks for explaining it very well
Emily says:
October 21, 2020 at 12:02 pm
Its amazing that everything on Earth is connected to the sun. The sun takes an integral role in the photosynthesis stage of the Carbon Cycle.
Kay-ann Gordon says:
February 15, 2020 at 2:53 pm
Can someone explain how respiration, combustion and decomposition is involved in the carbon cycle?
Stephen Mann says:
December 18, 2019 at 6:53 am
https://youtu.be/U-9UlF8hkhs
Brad Follett says:
October 26, 2019 at 5:51 pm
Carbon facts in trillions of tons:
Atmosphere. 0.85 TT. .0008%
Plants and Soil. 2.00. TT. .0020%
Fossil Fuels. 10.00. TT. .0100%
Oceans. 38.00. TT .0380%
Carbonaceous Rocks. 100,000. TT. 99.9490%
There is currently almost 4 times more CO2 dissolved in the oceans than there is in all fossil found on earth. Think about it.
Brad Follett says:
October 26, 2019 at 5:23 pm
Sorry, but you people missed it by a mile. 99.95% of all carbon on earth has been absorbed by the oceans and is locked up in carbonaceous rock, mountains of it. A further .01% is locked up in fossil fuels bringing the total to 99.96% of all CO2 on earth LOCKED AWAY. The oceans currently have about .038% of the remainder absorbed and that leaves about .002% left for the atmosphere and land plants. Think about it, the oceans are still absorbing carbon and building reefs and locking more and more of carbon up into carbonaceous rocks. Yes, volcanoes are returning some CO2 to the cycle naturally but how did the world get to the 99.96% locked away before man stepped in with burning and cement production. I think maybe you people should be rewriting your thoughts on the carbon cycle and extinction theories.
PrestonPlayz says:
October 20, 2019 at 4:20 am
The carbon cycle is awesome, thanks for helping me! This was so useful for my assignment!
Daniel says:
October 20, 2019 at 4:15 am
Where does “oxygen in daytime” and “carbon dioxide in nighttime” come into play?
Mariya says:
October 13, 2019 at 7:50 am
Does anyone know how freeze thaw (on rocks) affects combustion?
I really need an answer for my essay in A-level geography.
Joy says:
July 31, 2019 at 6:03 am
Thx for giving a good answer…… I searched everywhere but there was no response till I reached here. Thx a lot.
earthhow says:
January 28, 2019 at 4:23 am
Examples of carbon sinks = Oceans and forests are the biggest
Examples of carbon sources = Gasoline vehicles and forest fires
Alejandra Manzanedo says:
January 26, 2019 at 5:16 pm
What is a source and sink of carbon dioxide in the cycle?
Sophie says:
January 15, 2019 at 10:29 am
When does sugar broken down and converted to carbon dioxide come into play here?
Makayla says:
December 12, 2018 at 4:22 pm
What about volcanic activity going into the atmosphere?
Mark says:
December 9, 2018 at 8:37 am
Fossil fuels. Its funny how modern day environmentalists push a narrative invented by the OOG’s(original oil gangsters)

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