Carbon cycle in the ecosystem

Carbon cycle in the ecosystem

The carbon cycle is a cycle by which carbon is exchanged between the ecosystem and atmosphere of the Earth.


Carbon is the main component of all living organisms and the carbon cycle comprises a sequence of events that make the Earth capable of sustaining life.

The carbon cycle

Carbon cycle in the ecosystem
Carbon cycle
  • Carbon in the Earth’s atmosphere exists mainly in form of carbon dioxide. Carbon dioxide is partially responsible for the greenhouse effect which leads to global warming.
  • Carbon dioxide is removed from the atmosphere primarily through photosynthesis. During photosynthesis, green plants take in carbon as carbon dioxide and combine it with water to form carbohydrates. Some of the carbohydrates are stored in the plant and some are converted to fat and plant protein in the plant.
  • Animals eat the plants. In animals, carbohydrates and fats are used for energy during respiration releasing the carbon as carbon dioxide back into the atmosphere. The proteins are used for growth and repair of worn out tissues.
  • Carbon dioxide is also released back into the atmosphere when plants and animals die and decay.
  • Fossil fuels like oil, coal and natural gas are formed from plants over millions of years. During combustion, these fuels release carbon dioxide back into the atmosphere.

Greenhouse effect and the carbon cycle

Over the past two centuries, human activities have increased the amount of carbon in the atmosphere by about 50% as of year 2020, mainly in the form of carbon dioxide by:

  • reducing the ecosystems’ ability to extract carbon dioxide from the atmosphere, e.g. by chopping down trees.

  • emitting it carbon dioxide directly, e.g. by burning fossil fuels.

Atmospheric carbon dioxide is one of the gases that keep the earth warm by trapping the sun’s radiant energy in the atmosphere instead of allowing it to radiate back into space. This is called the greenhouse effect.

An increase in carbon dioxide level in the atmosphere results in an increase in overall temperatures on earth. This slight increase in temperature, with time, causes major changes in world temperatures, resulting in melting of ice caps and flooding of coastal areas.