AQA · GCSE · Combined Science
Course version: 8464 · Version from Sept 2018
Human activities which contribute to an increase in greenhouse gases in the atmosphere: describe uncertainties in the evidence base
Uncertainty in the evidence base means the extent to which climate data and conclusions may be incomplete, imprecise or open to more than one interpretation.
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Uncertainty in the evidence base means the extent to which climate data and conclusions may be incomplete, imprecise or open to more than one interpretation. Describe it by naming sources of uncertainty and explaining their effect. Measurement uncertainty arises from instrument accuracy and calibration, for example a thermometer reading of 15.0 °C carries an uncertainty of about ±0.5 °C. Natural variability, such as El Niño years, makes short records hard to interpret. Sparse coverage in oceans and polar regions, gaps in historical records and changing station locations add further uncertainty. Computer models carry uncertainty because future emissions, feedbacks and cloud behaviour are not fully known. Scientists reduce uncertainty with more measurements, better instruments and multiple independent lines of evidence, but some uncertainty always remains.
What earns the marks
- States that uncertainty means data or conclusions may be imprecise, incomplete or open to more than one interpretation.
- Identifies measurement uncertainty from instrument accuracy, calibration and reading error, giving an example such as ±0.5 °C.
- Explains uncertainty from natural variability and from limited or uneven geographical and historical coverage.
- Explains that computer models contain uncertainty because future emissions and feedbacks such as cloud behaviour are not fully known.
- Describes how uncertainty is reduced, for example more measurements, improved instruments and multiple independent lines of evidence.
Common mistakes and how to put them right
Confusing uncertainty with error or with being wrong.
Put it right by explaining that uncertainty is a quantified range within which the true value probably lies.
Claiming uncertainty means scientists know nothing.
Put it right by stating that evidence can still strongly support a conclusion while carrying a stated range.
Giving only one source of uncertainty.
Put it right by covering measurement, natural variability, coverage and modelling uncertainty.
Exam tips
- Name the source of uncertainty and then explain its effect on the conclusion.
- Use numerical examples such as ±0.5 °C or a stated percentage range to make the description precise.
- Link each uncertainty to how it could be reduced, showing understanding of scientific method.
Try the lesson
The start of the Human activities which contribute to an increase in greenhouse gases in the atmosphere: describe uncertainties in the evidence base lesson, made from checked teaching notes for this specification point.
Have a go first
Scientists use computer models to predict future global temperatures. Why can these predictions never be exact?
Listen
Uncertainty in the evidence base means the extent to which climate data and conclusions may be incomplete, imprecise or open to more than one interpretation. Describe it by naming sources of uncertainty and explaining their effect. Measurement uncertainty arises from instrument accuracy and calibration, for example a thermometer reading of 15.0 °C carries an uncertainty of about ±0.5 °C. Natural variability, such as El Niño years, makes short records hard to interpret. Sparse coverage in oceans and polar regions, gaps in historical records and changing station locations add further uncertainty. Computer models carry uncertainty because future emissions, feedbacks and cloud behaviour are not fully known. Scientists reduce uncertainty with more measurements, better instruments and multiple independent lines of evidence, but some uncertainty always remains. A strong answer earns marks for these points. States that uncertainty means data or conclusions may be imprecise, incomplete or open to more than one interpretation. Identifies measurement uncertainty from instrument accuracy, calibration and reading error, giving an example such as ±0.5 °C. Explains uncertainty from natural variability and from limited or uneven geographical and historical coverage. Explains that computer models contain uncertainty because future emissions and feedbacks such as cloud behaviour are not fully known. A common slip: Confusing uncertainty with error or with being wrong. Instead, explaining that uncertainty is a quantified range within which the true value probably lies. Exam tip: Name the source of uncertainty and then explain its effect on the conclusion.
Key words
Say what each word means before you turn the card.
Measurement uncertainty
Try answering aloud or in your head before turning the card.
Natural variability
Try answering aloud or in your head before turning the card.
Model limitations
Try answering aloud or in your head before turning the card.
Improving evidence through further data
Try answering aloud or in your head before turning the card.
See every definition
- Measurement uncertainty
- Arises from instrument accuracy and calibration, for example a thermometer reading of 15.0 °C carries an uncertainty of about ±0.5 °C.
- Natural variability
- Such as El Niño years, makes short records hard to interpret.
- Model limitations
- Computer models carry uncertainty because future emissions, feedbacks and cloud behaviour are not fully known.
- Improving evidence through further data
- Scientists reduce uncertainty with more measurements, better instruments and multiple independent lines of evidence, but some uncertainty always remains.
There is more to this lesson
The full lesson goes on to check your understanding and help you earn the marks. Create a free account to carry on, with your progress saved.
A week of Premium from your first lesson · Then the free plan continues · No card, no charge
Test your understanding of Human activities which contribute to an increase in greenhouse gases in the atmosphere: describe uncertainties in the evidence base
Active recall beats re-reading. Take an instant quiz now to test what you’ve learned and lock it into long-term memory.
A week of Premium from your first lesson · Then the free plan continues · No card, no charge