Carbon cycle

Definition

The carbon cycle is the process through which carbon is exchanged among the atmosphere, oceans, soil, and living organisms. This cycle is crucial for regulating Earth's climate, as it helps control the levels of carbon dioxide, a significant greenhouse gas, in the atmosphere. Through various processes like photosynthesis, respiration, and decomposition, carbon is transferred and transformed, connecting terrestrial and marine ecosystems and influencing the chemical composition of seawater.

5 Must Know Facts For Your Next Test

1. Carbon dioxide is absorbed by the oceans, where it can be utilized by marine organisms for photosynthesis or lead to ocean acidification if levels are too high.
2. The ocean acts as a significant carbon sink, storing vast amounts of carbon and playing a key role in regulating atmospheric carbon levels.
3. Carbon is stored in various forms throughout the carbon cycle, including organic matter in living organisms, dissolved CO2 in seawater, and fossil fuels in the Earth’s crust.
4. Human activities such as burning fossil fuels and deforestation have significantly disrupted the natural carbon cycle, leading to increased greenhouse gas concentrations and climate change.
5. The balance of the carbon cycle is vital for maintaining the health of marine ecosystems and influences global climate patterns.

Review Questions

• How does the carbon cycle link marine ecosystems to terrestrial systems through processes like photosynthesis and respiration?
  • The carbon cycle connects marine ecosystems to terrestrial systems primarily through photosynthesis and respiration. In the ocean, phytoplankton utilize sunlight to perform photosynthesis, absorbing carbon dioxide from the water. This organic carbon then enters the food web and can eventually be respired back into CO2 by marine organisms. On land, plants absorb atmospheric CO2 for photosynthesis while animals respire it back into the atmosphere. This continuous exchange ensures that carbon is cycled between both ecosystems.
• Discuss the impact of ocean acidification on the chemical composition of seawater and marine life as a result of changes in the carbon cycle.
  • Ocean acidification occurs when excess atmospheric CO2 dissolves in seawater, lowering its pH and altering its chemical composition. This change affects carbonate ions that are essential for marine organisms like corals and shellfish to build their shells. As these organisms struggle to maintain their structures in more acidic conditions, it can lead to decreased biodiversity and disrupt food webs. The changes in seawater chemistry also affect nutrient availability and overall ecosystem health.
• Evaluate how human activities have altered the natural balance of the carbon cycle and what implications this has for global climate change.
  • Human activities, particularly fossil fuel combustion and deforestation, have significantly altered the natural balance of the carbon cycle by increasing atmospheric CO2 levels. This disruption has resulted in an enhanced greenhouse effect, leading to global warming and climate change. As more carbon enters the atmosphere than can be naturally sequestered by oceans and terrestrial ecosystems, we face rising temperatures, changing weather patterns, and impacts on biodiversity. The long-term consequences could threaten food security, freshwater resources, and coastal communities worldwide.

Related terms

photosynthesis:

The process by which green plants, algae, and some bacteria convert light energy into chemical energy by synthesizing glucose from carbon dioxide and water.

respiration: The biochemical process in which organisms convert glucose and oxygen into energy, releasing carbon dioxide and water as byproducts.

ocean acidification: The decrease in pH levels of ocean waters due to the absorption of excess carbon dioxide from the atmosphere, which can impact marine life.