Human activities which contribute to an increase in greenhouse gases in the atmosphere: Based on peer-reviewed evidence, many scientists believe that human activities will cause the temperature of the Earth’s atmosphere to increase at the surface and that this will result in global climate change.

The idea

Peer-reviewed evidence means research checked by independent experts before publication, giving it greater reliability than unverified claims. Many scientists use such evidence, including global temperature records, ice-core data, satellite measurements and computer models, to conclude that human activities are increasing greenhouse gases and that this will raise surface temperatures. Warmer surface temperatures are expected to drive global climate change, meaning long-term shifts in weather patterns, sea level and ecosystems worldwide. A good answer distinguishes weather from climate, explains that the belief rests on peer-reviewed evidence, and states both parts: surface temperature increase and resulting global climate change.

What earns the marks

• Explains that peer-reviewed evidence has been checked by independent experts, making it more reliable than unreviewed claims.
• States that many scientists, not all, accept the conclusion, showing awareness that scientific agreement is strong but not universal.
• Links human activities such as burning fossil fuels and farming to increased greenhouse gas concentrations.
• States that increased greenhouse gases enhance the greenhouse effect, raising the temperature of the Earth's atmosphere at the surface.
• Explains that rising surface temperatures cause global climate change, such as altered weather patterns, ice melting or sea level rise.
• Uses the terms 'global climate change' and 'surface temperature' accurately rather than treating weather and climate as the same.

Common mistakes and how to put them right

• Saying all scientists believe the conclusion.

  Put it right: Write that many scientists believe it based on peer-reviewed evidence, since scientific conclusions are always open to further evidence.

• Confusing weather with climate.

  Put it right: Weather is short-term and local, while climate change is a long-term shift in global patterns.

• Claiming the greenhouse effect is entirely human-made.

  Put it right: The greenhouse effect is natural and necessary, but human activities enhance it.

• Describing peer review as a single scientist checking work.

  Put it right: Peer review involves independent experts evaluating methods and evidence before publication.

Exam tips

• Use the phrase 'peer-reviewed evidence' and briefly say what it means, as this is the basis named in the statement.
• Answer in two linked steps: human activities raise greenhouse gases, which raises surface temperature, which causes global climate change.
• Avoid absolute words such as 'proves' or 'all scientists'; use 'many scientists believe' or 'evidence suggests'.
• If asked to evaluate, compare peer-reviewed evidence with unreliable sources such as unverified websites or single opinions.