Understanding Models: Atlas of Change

1. Understanding Models Activity 3: Atlas of Change

2. What does “model” mean to you?

3. What is a scientific model? • Model: a representation of a part of the real world • A model shares some characteristics with the thing it represents, but not all. • A model is simpler than the real thing. • There are many different types of models. “All models are wrong, but some are useful.” -George Box

4. What are models for? • Models explain observations or data • Example: Geocentric (Earth-centered) model of the solar system • Explained observed motion of stars • Predicted future motion 16th century representation of the geocentric model by Portuguese cosmographer Bartolomeu Velho.

5. Geocentric vs. Heliocentric Models • In 1543 Copernicus suggested that the sun (not the Earth) was at the center of the solar system. • Heliocentric (sun-centered) solar system • Explains some observations that the geocentric model could not explain Early 18th century depiction of the heliocentric model of the solar system.

6. Assessing Accuracy of Models • Accuracy of projections • Hindcasts • Forecasts look forward; hindcasts look backward • Does the model fit observations made so far?

7. Assessing Accuracy: Climate Models • Test against recent data • Test against data from the distant past • Test against other models Scientists collect and analyze ocean sediments for clues into what the climate was like in the distant past.

8. Scientific Uncertainty • Understanding uncertainty • How we use the term • How scientists use the term • Complexity and uncertainty • Many different variables interact with each other • Difficult to predict with certainty • Examples • Weather models • Ecosystem models • Climate models

9. Dealing with Uncertainty • Using statistics • Run model multiple times (virtual experiments) • Use multiple models and combine results • Suggest a range of probable outcomes

10. Example: Modeling Hurricanes

11. Other Uses for Models Understanding a system better

12. Outputs of Models Current conditions Hadley (High Emissions) Hadley (Low Emissions)