Human Activities and Climate Change
Practise Human Activities and Climate Change for GCSE Chemistry with this free worksheet and full mark scheme — Foundation and Higher exam-style questions with worked answers for AQA, Edexcel and OCR. Be ready to interpret climate data and explain why an increase in average global temperature drives climate change.
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These worksheets and mark schemes are original, written for Virtus Academy and checked against the current AQA, Edexcel and OCR specifications. Every worksheet comes with a full mark scheme.
Topic overview
Human activities increase the amounts of greenhouse gases in the atmosphere, and scientists believe this is causing the average global temperature to rise.
Carbon dioxide levels rise from burning fossil fuels and from deforestation, which removes trees that would otherwise absorb it. Methane levels rise from livestock farming, particularly cattle, and from decomposition in landfill sites.
Many scientists agree that human activities will cause the temperature to rise, based on peer-reviewed evidence. But it is difficult to model such complex systems, which leads to simplified models, speculation and opinions presented in the media that may be biased or based on only part of the evidence.
Revision notes
Sources of extra carbon dioxide
Burning fossil fuels for energy, transport and industry releases carbon dioxide.
Deforestation reduces the number of trees carrying out photosynthesis, so less carbon dioxide is removed from the atmosphere.
Sources of extra methane
Livestock farming, particularly cattle, produces methane during digestion.
Decomposition of waste in landfill sites also releases methane. Both have increased with population growth and changing diets.
Evaluating evidence
Many scientists agree human activities will cause global temperature to rise, based on peer-reviewed evidence.
However, it is difficult to model such complex systems. This leads to simplified models, speculation, and opinions in the media that may be biased or based on only part of the evidence.
Key points
- Burning fossil fuels increases carbon dioxide.
- Deforestation reduces carbon dioxide removal.
- Livestock farming increases methane.
- Landfill decomposition releases methane.
- Scientists agree based on peer-reviewed evidence.
- Complex systems are difficult to model.
Worked examples
Example 1
Give two human activities that increase the amount of carbon dioxide in the atmosphere. [2 marks]
Model answer
Burning fossil fuels for energy and transport (1 mark). Deforestation, which reduces the number of trees removing carbon dioxide by photosynthesis (1 mark).
Example 2
Give two human activities that increase the amount of methane in the atmosphere. [2 marks]
Model answer
Livestock farming, particularly cattle (1 mark). Decomposition of waste in landfill sites (1 mark).
Example 3
Explain why some media reports about climate change may be unreliable. [2 marks]
Model answer
It is difficult to model such complex systems, which leads to simplified models and speculation (1 mark). Media reports may be biased or based on only a part of the available evidence (1 mark).
Common mistakes
Saying deforestation directly releases carbon dioxide only.
It also reduces the removal of carbon dioxide by photosynthesis.
Confusing sources of methane and carbon dioxide.
Livestock and landfill give methane; fossil fuels give carbon dioxide.
Saying all scientists disagree.
Many agree, based on peer-reviewed evidence. The uncertainty is in the detail of modelling.
Not mentioning peer review.
It is what distinguishes scientific evidence from media speculation.
Exam tips
- Learn separate lists for carbon dioxide and methane sources.
- Explain deforestation through reduced photosynthesis.
- Mention peer review when discussing evidence quality.
- Acknowledge both the consensus and the modelling difficulty.
Key terms
- Deforestation
- The large-scale removal of trees.
- Peer review
- The checking of scientific work by other scientists.
- Model
- A simplified representation used to make predictions.
- Bias
- A tendency to present only part of the evidence.
Related topics
Written and reviewed against the current AQA, Edexcel and OCR specifications. Spotted an error? Let us know.