1. Bellwork 5/13 How old is Earth? When did life begin on our planet?
What is Continental Drift?
How many Ice Ages has Earth had?
Is climate change natural?

2. Earth’s Geologic Past

3. Continental Drift

4. What kind of changes must have occurred?
“Baby Earth” to Today
What kind of changes must have occurred?

5. Paleoclimatology
the study of past climates

6. How an Ice Age is Born

7. Two Main Factors
Solar Radiation
Composition of Atmosphere

8. How can solar radiation change?
Eccentricity: change in Earth’s orbital path
Tilt: change in Earth’s axial angle
Precession: “wobble cycle”

9. How can atmospheric composition change?
Biology
Transition between Glacial & Interglacial periods
Tectonic activity
Geologic activity
Emissions

10. How do we study this? Ice cores Corals Ocean sediment cores
Leaf-margin analysis
tree rings
Radioactive Carbon dating
Fossil pollen

11. Wait, so what’s the difference between “Climate Change” and “Global Warming”?
“Global warming refers only to the Earth’s rising surface temperature, while climate change includes warming and the “side effects” of warming—like melting glaciers, heavier rainstorms, or more frequent drought.”—NOAA
Typically “Global warming” refers to human-caused changes, while Climate Change includes natural phenomena

12. So, how has Earth’s Climate changed throughout billions of years?
Let’s investigate.