Water and carbon cycles 5


The most abundant elements of the global carbon cycle are:

  • Oxygen
  • Carbon
  • Hydrogen
  • Nitrogen
  • Calcium
  • Phosphorous

Carbon joins other elements to form compounds. It is present in the atmosphere, oceans, soils and crust

Flux - movement of carbon between reservoirs.

Fluxes connect reservoirs together in integrated systems to create cycles and feedbacks; the transfers are continued.

On a short scale, plants take carbon out of the atmosphere through photosynthesis and release it back into the atmosphere through repsiration

On a long scale, carbon from dead plant material can be incorporated into soils, where it may reside for years, decades or centuries before being broken down by soil microbes and released back into the atmosphere.

On a longer scale, organic matter that became buried in deep sediments, was slowly transformed into deposits of coal, oil and natural gas, the fossil fuels we use today. When these substances are burned, carbon that has been stored for millions of years, is released once again to the atmosphere in the form of carbon dioxide.

Carbon dioxide is important because it contributes to the greenhouse effect. This is where heat generated from sunlight at the Earth's surface is trapped by certain gases and prevented from escaping through the atmosphere.

In recent years, carbon dioxide has received much attention because its concentration in the atmosphere has risen to 30% above natural background levels and will continue to rise. Because it is a greenhouse gas, this increase is believed to be causing a rise in global temperatures. This is the primary cause of climate change and is the…


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