Carbon cycle

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  Carbon flows between each reservoir in an exchange called the carbon cycle, which has slow and fast components
• Most of Earth's carbon is stored in rocks and sediments
• Carbon is the backbone of life on Earth. It is the fourth most abundant element in the Universe
• Where Earth's carbon is stored

  • Rocks (65,500 billion metric tons)
  • Ocean
  • Atmosphere
  • Plants
  • Soil
  • Fossil fuels
• We need carbon, but that need is also entwined with one of the most serious problems facing us today: global climate change
• Photosynthesis


  CO2 + H2O → C6H12O6 + O2
• Cellular Respiration


  C6H12O6 + 6O2 → 6CO2 + 6H2O
• Carbon fixation by consumers


  The process by which heterotrophs obtain energy and nutrients by consuming other organisms or organic matter
• Animals release carbon as methane (CH4)


  1. During digestion

  2. Soil contains decomposers, releases carbon into the atmosphere
• CO2 released during decomposition


  Can be used by plants during photosynthesis
• When animals die, they decompose, and their remains become sediment, trapping the stored carbon in layers that eventually turn into rock or minerals
• Some of this sediment might form fossil fuels, such as coal, oil, or natural gas, which release carbon back into the atmosphere when the fuel is burned
• Fossil fuels

  • Coal
  • Oil
  • Natural gas
• Plants release carbon back to the environment through respiration
• Decomposers


  Break down organic matter as a form of nutrients for the soil
• Mining gets the fossil fuels and coal to use as a source of energy back into the environment
• Ways to return carbon to the environment

  • Respiration
  • Combustion
  • Decomposition
• Slow carbon cycle


  The ocean has the greatest quantity of cycled carbon and stores a large amount of carbon
• Marine life uses carbonate from the water to build shells and skeletons
• The ocean holds 50x more CO2 than the atmosphere and 20x more CO2 than land plants
• Phytoplankton release carbon dioxide back to the water through respiration
• Fish consuming zooplankton are considered secondary consumers
• Increase in CO2


  Impacts global climate change
• Greenhouse gas


  Stays in the Earth's atmosphere and traps more heat than it re-emits back to space, leading to global warming and climate change
• The world is now warming faster than at any point in recorded history. Warmer temperatures over time are changing weather patterns and disrupting the usual balance of nature
• Solar radiation emitted towards Earth


  Some is absorbed, some is re-emitted back to space
• Increase in CO2


  Causes more infrared radiation to be trapped in the atmosphere instead of re-emitted to space
• Carbon cycle


  A fundamental biogeochemical cycle that describes the movement of carbon (in various forms) through the Earth's atmosphere, hydrosphere (oceans, rivers, lakes), geosphere (Earth's crust), and biosphere (living organisms)
• Carbon


  • An essential element for life on Earth
  • The carbon cycle plays a crucial role in maintaining the planet's climate and supporting all living organisms
• Photosynthesis


  1. Green plants, algae, and some bacteria use sunlight to convert atmospheric carbon dioxide (CO2) into organic carbon compounds, primarily glucose (a sugar)

  2. This is the process by which carbon from the atmosphere enters the terrestrial biosphere
• Respiration


  1. All living organisms, including plants, animals, and microorganisms, break down organic carbon compounds (like glucose) to produce energy for their metabolic processes

  2. This releases CO2 back into the atmosphere

  3. While photosynthesis stores carbon, respiration releases it
• Decomposition


  1. Decomposers, such as bacteria and fungi, break down dead organic matter, including dead plants and animals

  2. This process releases carbon stored in organic materials back into the soil or water as CO2 or other carbon compounds
• Combustion


  1. When organic materials (e.g., wood, fossil fuels) are burned, they undergo combustion, which releases CO2 and other carbon compounds into the atmosphere

  2. Human activities, such as burning fossil fuels for energy and deforestation, significantly contribute to this release of carbon dioxide
• Ocean Uptake


  1. The world's oceans act as a significant carbon sink

  2. They absorb large amounts of CO2 from the atmosphere, primarily through physical and chemical processes

  3. This dissolved carbon can then be used by marine organisms and eventually deposited as calcium carbonate sediments on the ocean floor
• Photosynthesis in the Ocean

  1. Phytoplankton and marine plants in the ocean carry out photosynthesis, similar to terrestrial plants

  2. They convert CO2 from the atmosphere into organic carbon compounds, which are then transferred through the marine food web
• Volcanic Activity


  1. Volcanic eruptions release carbon stored in Earth's mantle into the atmosphere as CO2

  2. While volcanic activity is a natural part of the carbon cycle, it contributes a relatively small amount of carbon compared to human activities
• Weathering and Erosion


  1. Over long time scales, physical and chemical weathering processes break down rocks, releasing carbon compounds into rivers and oceans

  2. This carbon can eventually be deposited as sedimentary rocks