Aug 22, 2024
What is carbon?
This is the first in a series of seven texts that explain the carbon cycle, its origins, its impacts, and how it connects to the climate crisis and market solutions. We'll start with the basics to level the knowledge between those who are new and those who have been following this debate for a long time.
We begin with a fundamental question: what is carbon?
The element carbon
Carbon is a chemical element with atomic number 6 — meaning it has 6 protons and 6 electrons — and an atomic mass of 12. It is the sixth most abundant element in the universe and ranks in the 15th position in abundance in the Earth's crust, making it common but far from trivial.
Its main characteristic is tetravalence: it can form up to four covalent bonds with other atoms. This property gives carbon a unique versatility, allowing it to compose an enormous variety of molecules — from the simplest to the most complex.
Where is carbon present?
The short answer is: almost everywhere. Carbon is in:
• Inorganic molecules, such as methane (CH₄) and carbon dioxide (CO₂);
• Complex organic molecules, like glucose (C₆H₁₂O₆);
• All living beings — every cell carries carbon in its fundamental structure.
These structures include four major molecular groups of life:
• Proteins
• Carbohydrates
• Lipids
• Nucleic acids (like DNA)
In other words: life is essentially an arrangement of carbon.
But it is also outside living organisms. Carbon appears:
• In the atmosphere, as CO₂ and CH₄ (methane);
• In water, dissolved in the form of carbonic acid (H₂CO₃) or bicarbonate (HCO₃⁻);
• In fossil fuels, such as oil and natural gas;
• In minerals, like chalk, coal, marble, graphite, and diamond;
• In limestone rocks, such as limestone and dolomite, formed by carbonates.
The multiple faces of carbon
These forms of carbon manifestation vary greatly in their dynamics:
• Some are extremely stable, like minerals and carbonate rocks.
• Others are highly mobile, like gases in the atmosphere and organic compounds in plants.
This difference — between static and dynamic carbon — is essential to understanding how the carbon cycle works and why it is so central in discussions about climate, energy, and land use.
In the next post, we will explore why we talk so much about carbon when discussing climate change — and how an element that represents less than 0.05% of the atmosphere can have such a significant impact on the planet.