Evaluating scientific conclusions on controversial issuesSpec 5.25
In short
Scientific conclusions about controversial issues, such as how much humans are affecting climate change and what should be done, can depend on who reaches them. Individuals and organisations may have vested interests, select data or use different assumptions. Evidence should be judged by checking the source, the funding, peer review and whether the conclusion matches the data.
Climate change is a controversial issue because the actions needed have economic, political and social consequences. The scientific evidence may be the same, but the conclusions drawn can depend on who is reaching them and why.
- Vested interest: an organisation that profits from fossil fuels may emphasise uncertainty, while an organisation that campaigns for the environment may emphasise the worst predictions.
- Funding: who paid for the research may influence which questions are asked and how results are reported.
- Selection of data: a conclusion may use only the data that support it (a narrow time period, or one region), or compare different measurements.
- Qualifications and expertise: a conclusion from experts in climate science is more reliable than one from people without relevant expertise.
- Peer review: research that has been checked by other independent scientists before publication is more reliable than claims that have not.
- Media and politics: reports in the media may simplify, exaggerate or present a balanced debate as if scientists were equally divided.
- Different assumptions: governments and countries weigh economic costs, development and fairness differently, so they may disagree on actions even when they agree on the science.
To evaluate a source, ask: who wrote it, who funded it, what evidence is used, is it from a peer-reviewed source, is the data selected, and is the conclusion supported by the data? Then give a judgement.
Written and checked against the Edexcel International A Level Biology (YBI11) specification · Updated October 2026