Carbon cycle

Definition

The carbon cycle is the continuous process through which carbon is exchanged between living organisms, the atmosphere, oceans, and the Earth's crust. It plays a crucial role in regulating the Earth's climate and supporting life by facilitating the movement of carbon through various forms such as carbon dioxide, organic matter, and fossil fuels. This cycle is interconnected with other Earth systems, affecting everything from plant growth to the formation of sedimentary rocks.

5 Must Know Facts For Your Next Test

1. The carbon cycle includes several key processes: photosynthesis, respiration, decomposition, and combustion, which all contribute to the movement of carbon between different reservoirs.
2. Carbon exists in various forms within the cycle, including as carbon dioxide in the atmosphere, organic matter in plants and animals, and in fossil fuels within the Earth's crust.
3. Human activities, particularly fossil fuel combustion and deforestation, have significantly altered the natural carbon cycle, leading to increased levels of atmospheric carbon dioxide and climate change.
4. Oceans act as both a source and sink for carbon, absorbing large amounts of CO2 from the atmosphere and storing it in marine organisms or sediments.
5. The long-term storage of carbon occurs in sedimentary rocks and fossil fuels, where carbon can remain trapped for millions of years before being released back into the cycle.

Review Questions

• How do photosynthesis and respiration contribute to the carbon cycle?
  • Photosynthesis allows plants to absorb carbon dioxide from the atmosphere and convert it into glucose while releasing oxygen. This process stores carbon in plant biomass. Respiration, on the other hand, occurs when living organisms break down organic matter to obtain energy, releasing carbon dioxide back into the atmosphere. Together, these two processes create a balance within the carbon cycle by continuously moving carbon between living organisms and the atmosphere.
• What impact do human activities have on the natural carbon cycle?
  • Human activities like burning fossil fuels for energy and clearing forests significantly disrupt the natural carbon cycle. These actions increase atmospheric levels of carbon dioxide by releasing stored carbon from fossil fuels and reducing the number of trees available to absorb CO2 through photosynthesis. The result is an enhanced greenhouse effect, which contributes to global warming and climate change, showcasing how interconnected human actions are with Earth’s dynamic systems.
• Evaluate how changes in oceanic conditions affect the carbon cycle and overall climate regulation.
  • Changes in oceanic conditions, such as temperature increases or acidification due to elevated atmospheric CO2 levels, can significantly affect the carbon cycle. Warmer oceans reduce their ability to absorb CO2, leading to higher atmospheric concentrations. Additionally, acidification impacts marine life, particularly organisms that rely on calcium carbonate for their shells and skeletons. These shifts not only alter local ecosystems but also have broader implications for climate regulation by diminishing natural sinks for atmospheric carbon.

Related terms

photosynthesis: The process by which green plants and some other organisms convert carbon dioxide and sunlight into glucose and oxygen, playing a critical role in the carbon cycle.

respiration: The process by which living organisms convert organic matter into energy, releasing carbon dioxide back into the atmosphere, which is vital for the carbon cycle.

fossil fuels: Natural fuels formed from the remains of ancient organisms, such as coal and oil, that store carbon and release it when burned, impacting the carbon cycle.