What is the carbon cycle?
We explain what the carbon cycle is and what this biogeochemical circuit consists of. In addition, the importance of this cycle for life.
The carbon cycle was discovered by scientists Joseph Priestley and Antoine Lavoisier.
The carbon cycle is a biogeochemical circuit for the exchange of matter (specifically carbon-containing compounds) between the biosphere, the pedosphere, the geosphere, the hydrosphere and the Earth’s atmosphere. It was discovered by European scientists Joseph Priestley and Antoine Lavoisier, and along with water and nitrogen, it is part of the cycles that allow the sustainability of life on our planet.
Since carbon (C) is a key element for life and for most of the known organic compounds, it is involved in numerous substances of organic (and inorganic) origin, in a continuous transmission that allows its reuse and recycling, sustaining the levels of this element in an overall balance.
Carbon in the world exists in different forms and domains: from underground carbon mineral reserves and inorganic carbon dissolved in seawater, to carbon dioxide in the atmosphere resulting from volcanic emissions or from the respiration of living beings, as well as from the processes of decomposition of organic matter in swamps and other terrains. For carbon cycle effects, some of them are considered reservoirs and other exchange routes.
Broadly speaking, carbon stocks are: atmospheric carbon, the content in the body of living beings in the biosphere (including marine and aquatic beings), carbon dissolved in seawater and deposited at the bottom of the oceans, and mineral deposits in the earth’s crust, including deposits of petroleum and other hydrocarbons.
The routes of exchange between these deposits are:
- The processes of fermentation and decomposition. Large deposits of organic matter are rich in carbon and in organisms that live from the decomposition and transformation of this matter, obtaining energy in exchange and releasing gases into the atmosphere such as methane (CH4) or CO2.
- Breathing and photosynthesis. Together with other metabolic biotic processes, these processes respectively release and capture carbon dioxide into the atmosphere as a by-product or input of their biochemical pathways. The carbon in CO2 attaches to plants and is released along with water vapor when animals breathe.
- Ocean gas exchange. The oceans evaporate by the action of the sun, as established by the water cycle. In this process, the water vapor produced and released into the atmosphere also facilitates the exchange of gases between the atmosphere and the ocean, allowing carbon to dissolve in the water, where it is fixed by photosynthetic plankton.
- Sedimentation processes. Both on land and at sea, excess carbon in decomposing organic matter, which is not sequestered and processed by decomposing life forms, is going to pile up and sediment at the bottom of the oceans or in the various layers of the earth’s crust, where it forms fossils, hydrocarbon deposits or reactive sediments.
- Natural combustion or by the hand of mankind. Human industrial processes and spontaneous forest fires must be taken into account in this cycle, as they are responsible for the annual increase in carbon in the atmosphere, in the form of greenhouse gases. This is due to the burning of fossil fuels, the release of organic gases from human industry, or eventual natural volcanic emissions.
All these processes occur at the same time and constitute a delicate balance cycle, allowing carbon to circulate in different environments and as part of very different kinds of substances. An interruption of this circuit would mean the impoverishment of many vital areas and, possibly, the end of life as we know it.