Human Activity & Climate Change

  • Human population is increasing and with it the global demand for food, water, consumer goods, housing and energy which are supplied with greater and more widespread industrialization.
  • This creates more waste so more landfill sites are needed which increases the amount of methane by decomposition.
  • The increased energy demands are met in most cases by the burning of fossil fuels which produces CO2:

Fossil fuel + oxygen → energy + H2O + CO2

  • Added to this is the effect of deforestation on the amount of CO2 as large areas of forested land is being destroyed for building and agricultural activities.
  • Plants and trees remove CO2 during photosynthesis:

6CO2 + 6H2O → C6H12O6 + 6O2

  • Hence their removal increases the amount of atmospheric CO2 as there are less plants available to remove it during photosynthesis.
  • Increasing agricultural activities also cause an increase in methane production.
  • By analysis of the percentage of CO2 in the atmosphere and the changes in temperature over several hundred years, the evidence for the effects of CO2 on global temperature is convincing.
  • There is a clear correlation between both factors as shown in the graph below.

Climate Change - Graph CO2 Evolution, IGCSE & GCSE Chemistry revision notes

Graph showing the steady increase in atmospheric CO2 since 1700

Climate Change - Graph Temperature Evolution, IGCSE & GCSE Chemistry revision notes

Graph showing the steady increase in temperature from when accurate records exist

Uncertainty & Historical Accuracy

  • Advances in science and technology mean current levels of CO2 and global temperatures can be determined with a high degree of accuracy.
  • Historical data is much less accurate due to the lack of accurate instrumentation and methods.
  • Fewer locations would also have been measured due to the lack of satellites and transport.
  • There are some methods to estimate past levels, which include:
    • Analysis of the fossil record.
    • Analysis of trapped gas bubbles and tree rings.
    • The ice sheets also trap valuable samples of past atmospheric conditions.
  • Unfortunately, these methods, while providing at least some data, are not as precise as modern day techniques nor do they provide data which is representative on a global scale.
  • The complexity of the Earth’s climate and contributing factors make it a difficult task to produce a working model that clearly shows the link between global warming and Greenhouse gases.
  • This and other difficulties have led to hype and speculation in the media in recent times.

AQA GCSE Chemistry Notes

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Morgan Curtin Chemistry

Author: Morgan

Morgan’s passion for the Periodic Table begun on his 10th birthday when he received his first Chemistry set. After studying the subject at university he went on to become a fully fledged Chemistry teacher, and now works in an international school in Madrid! In his spare time he helps create our fantastic resources to help you ace your exams.