The carbon cycle. Image credit windows2universe.org

The carbon cycle. Image credit windows2universe.org

ZIMSEC O Level Combined Science Notes: The Carbon cycle

  • Carbon dioxide in the atmosphere is the source of carbon in ecosystems
  • Plants remove carbon dioxide from the air during photosynthesis and use it to build food compounds
  • Animals obtain the carbon by eating the plants
  • Carbon is released back into the atmosphere by animals, plants and micro-organisms when they respire
  • It is also released back into the atmosphere by human activities such as burning fossil fuels
  • Deforestation also leads to a build up of carbon dioxide in the atmosphere as there are fewer tress to photosynthesize

Greenhouse effect and global warming

  • Recently there has been a noticeable build up of the amount of carbon dioxide in the atmosphere
  • Carbon dioxide is one of the gases that acts as an insulator thus keeping the earth warm
  • It traps the sun’s energy in the atmosphere
  • When the amount of carbon dioxide in the atmosphere so does the overall temperature of the earth
  • This is called the greenhouse effect
  • The increase in temperature is very small but enough to cause changes in the earth’s climatic patterns
  • The greenhouse effect has also resulted in the melting of ice caps at the in the polar regions
  • It has also resulted in rising sea levels

Ways to reduce global warming

  • Carbon dioxide emissions can be reduced by burning less fossil fuels
  • Examples of fossil fuels are oil, coal and gas
  • Alternative sources of energy such as solar, hydro(water) and wind must be used
  • Deforestation has also to be reduced
  • Reafforestation and afforestation will also reduce the amount of carbon dioxide in the atmosphere

To access more topics go to the Combined Science Notes page.


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