Human Activity & Climate Change (Edexcel GCSE Chemistry: Combined Science)

• 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 climate conditions, which include:
  • Analysis of the fossil record and tree rings
  • Analysis of gas bubbles trapped in ice from hundreds of thousands of years ago

Correlating rising CO₂ levels and global temperatures

Graph showing the steady increase in atmospheric CO₂ since 1700

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

• Unfortunately, historical 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 in which some scientists have cast doubts on human activity and climate change
• However, academic surveys have shown that about 97% of climate scientists do believe human activity is causing 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 are 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
• Methane is produced in the digestive processes of animals, by the decomposition of vegetation, and by bacterial action in swamps
• Scientists agree that greenhouse gases are causing the average temperature of the Earth to increase by the enhanced greenhouse effect, which is causing global warming
• Climate change is when there is a shift in worldwide weather patterns and conditions
• Effects of global warming include difficulties in obtaining fresh drinking water, melting of the polar ice caps, flooding and flash fires, and the destruction of ecosystems

Dealing with Climate Change

• The production of greenhouse gases needs to be reduced drastically to avoid or at least slow climate change
• CO₂ emissions can be reduced by using renewable energy supplies such as solar or wind energy instead of burning fossil fuels
• Awareness and being conscientious about reducing energy usage and our carbon footprint is another way to reduce emissions
• Governments and economies in developed nations are slowly switching to greener and sustainable sources of energy and often offer financial incentives to companies in an effort to convince them to “go green”
• Other ways of mitigating the effects of climate change include:
  • Constructing flood defence systems in areas of low lying land
  • Developing new farming methods to include switching to crops that are better adapted to the new climate
  • Building more effective irrigation systems to ensure crops can get water during times of drought