5.3.4Unit 5: Respiration, Internal Environment, Coordination and Gene Technology
Models for Predicting Climate Change — IAL Edexcel Linear Revision Notes & Topical Questions
5 min read 5 parts Lesson 28 of 36 Unit quiz
Part 1 of 5Building a Model
Models use existing data to predict, and they are only as good as their assumptions.
Extrapolation
- Existing data on temperature and greenhouse gas levels are extended beyond the measured range to predict future values.
Scenarios
- Models are run with different assumptions about how much greenhouse gas humans will emit in future.
Combined models
- Data on gas levels can be fed into computer models of regional weather to predict local effects.
IPCC
- The Intergovernmental Panel on Climate Change brings together climate scientists to assess data and publish projections.
Part 2 of 5How Predictions Are Used
How Predictions Are Used
Planning
- Governments can plan defences, such as flood barriers, for the changes that models suggest are likely.
Research funding
- Predictions help decide which climate technologies and research areas deserve investment.
Changing behaviour
- Showing that high emissions lead to larger temperature rises encourages people to reduce fossil fuel use.
Energy choices
- Projections support a move to renewable energy such as wind and solar power and to lower meat consumption.
Part 3 of 5Limitations of Models
1
It is not known which emissions scenario will happen, because it depends on how effectively people cut emissions.
2
Future technologies such as carbon capture may or may not work at scale, so their effect cannot be included reliably.
3
The exact effect of a given gas concentration on temperature is not fully known, and climate systems are complex.
4
A tipping point could cause sudden acceleration, for example thawing permafrost releasing methane that causes further warming.
5
Natural events such as a large volcanic eruption can cool the planet by reflecting sunlight, and cannot be predicted.
Part 4 of 5Evaluating a Prediction
Range of outcomes
- A good prediction presents a range of possible outcomes rather than a single exact value.
Quality of data
- Predictions are more reliable when based on large amounts of data from several independent sources.
Assumptions
- Check which assumptions were made, since a different assumption about emissions changes the result.
Further from the data
- Extrapolating a long way beyond the measured data increases the uncertainty.
Part 5 of 5Exam Checklist & Tips
5.3.4 – Key Points for the Exam
- Extrapolation Extending a trend in existing data to predict values outside the measured range.
- Model A simplified representation of a system used to make predictions.
- Tipping point A threshold beyond which change accelerates and may not be reversible.
- IPCC A group of scientists that assesses climate data and produces projections.
Common Mistakes
- Saying models predict one certain future; they give a range depending on the scenario chosen.
- Stating that uncertainty means global warming is not happening;
- it only limits how exactly the future can be predicted.
- Forgetting to name an actual limitation, such as an unknown emissions scenario or a tipping point.
- Treating extrapolation as measured data, when it is a prediction beyond what has been recorded.
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