Global Warming
Master Global Warming for GCSE Biology with this free worksheet and full mark scheme — Foundation and Higher exam-style questions with worked answers for AQA, Edexcel and OCR. Rising levels of carbon dioxide and methane increase the greenhouse effect; be ready to evaluate the evidence for and consequences of global warming.
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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
Levels of carbon dioxide and methane in the atmosphere are increasing, and this contributes to global warming.
These are greenhouse gases. They absorb energy that would otherwise be radiated away from the Earth, keeping the planet warm enough to support life. But higher concentrations trap more energy, raising average global temperature.
The consequences include rising sea levels from melting ice and thermal expansion, causing flooding and coastal erosion; changes in the distribution of species as temperature and rainfall patterns shift; and changes to migration patterns. Reduced biodiversity is a likely outcome as species unable to adapt or move die out.
Revision notes
Greenhouse gases
Carbon dioxide and methane are greenhouse gases.
They absorb energy that would otherwise be radiated away from Earth. Their concentrations are increasing because of human activity such as burning fossil fuels, deforestation and farming livestock.
Consequences
Sea levels rise as ice melts and as sea water expands when warmed, causing flooding and increased coastal erosion.
Changes in the distribution of species occur as temperature and rainfall patterns change. Migration patterns change, for example birds migrating further north.
Biodiversity impact
Species unable to adapt quickly enough, or to move to suitable conditions, may die out.
This reduces biodiversity. Because ecosystems depend on interdependence, the loss of one species can affect many others.
Key points
- Carbon dioxide and methane are greenhouse gases.
- They absorb energy that would otherwise be radiated away.
- Increasing levels raise average global temperature.
- Sea levels rise from melting ice and thermal expansion.
- Species distribution and migration patterns change.
- Global warming is likely to reduce biodiversity.
Worked examples
Example 1
Name two greenhouse gases whose levels are increasing. [2 marks]
Model answer
Carbon dioxide (1 mark) and methane (1 mark).
Example 2
Explain two consequences of global warming. [4 marks]
Model answer
Sea levels rise as ice melts and as sea water expands when it warms (1 mark), causing flooding and increased coastal erosion in low-lying areas (1 mark). The distribution of species changes as temperature and rainfall patterns shift (1 mark), so species may move to new areas or die out if they cannot adapt (1 mark).
Example 3
Explain why global warming may reduce biodiversity. [2 marks]
Model answer
Species that cannot adapt quickly enough to the changing conditions, or move to areas that suit them, will die out (1 mark), so the variety of species in an ecosystem falls (1 mark).
Common mistakes
Saying greenhouse gases are entirely harmful.
They keep the Earth warm enough to support life; the problem is increasing concentrations.
Forgetting thermal expansion.
Sea level rise comes from expanding warm water as well as melting ice.
Giving only one consequence when several are asked for.
Sea level, species distribution and migration patterns are all examinable.
Confusing global warming with the ozone layer.
They are separate issues.
Exam tips
- Name both required greenhouse gases.
- Include thermal expansion alongside melting ice.
- Give the consequence and its effect, not just the consequence.
- Link changing conditions to reduced biodiversity.
Key terms
- Greenhouse gas
- A gas that absorbs energy radiated from the Earth.
- Global warming
- The increase in average global temperature.
- Thermal expansion
- The increase in volume of water as it warms.
- Migration
- The seasonal movement of animals between regions.
Related topics
Written and reviewed against the current AQA, Edexcel and OCR specifications. Spotted an error? Let us know.