Students should be able to: describe briefly four potential effects of…

The idea

Global climate change arises because greenhouse gases such as carbon dioxide and methane absorb infrared radiation re-emitted by Earth, warming the atmosphere and oceans. Four potential effects to describe briefly are: rising sea levels as ice sheets and glaciers melt and warm water expands; more frequent and severe extreme weather such as heatwaves, droughts and heavy rainfall; changes to ecosystems and habitats, so some species shift range or decline; and impacts on agriculture and water supply, affecting food security and human health. Scale means the effects are global and long-lasting, spanning decades and continents. Risk means the likelihood and seriousness of harm, which is greater where populations are exposed and less able to adapt. Environmental implications include biodiversity loss, ocean acidification and altered nutrient cycles.

What earns the marks

• Names carbon dioxide and methane as greenhouse gases that absorb infrared radiation and warm the atmosphere.
• Describes at least four distinct effects, for example sea-level rise, extreme weather, ecosystem change and effects on agriculture or water supply.
• Explains scale as global and long-term, affecting many countries over decades rather than one local area.
• Explains risk as the combination of how likely an effect is and how serious its consequences would be.
• Links environmental implications to biodiversity, habitats, oceans or nutrient cycles.
• Uses the idea that some regions and communities are more vulnerable because they cannot adapt easily.

Common mistakes and how to put them right

• Confusing climate change with the ozone hole.

  Put it right: Ozone depletion is caused by CFCs and is a separate issue from greenhouse warming.

• Listing only one or two effects when four are required.

  Put it right: Prepare four clearly different examples and check each is genuinely distinct.

• Treating weather and climate as the same.

  Put it right: Weather is short-term local conditions while climate is the long-term pattern.

Exam tips

• Use command words carefully: describe means give the effect, discuss means develop scale, risk and implications.
• Keep each effect to one clear sentence so four effects fit comfortably in the time available.
• Where asked to discuss, add a sentence on why an effect is serious or who is most at risk rather than listing more effects.