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Transcript
Chapter 4 Section 3 Long Term climate Change OBJECTIVE: Analyze evidence of climate change over time. 1. In studying ancient climates scientists follow an important Principle: If plants and animals today need certain conditions to live, Then similar plants and animals in the past also required those Conditions. 2. Tree Rings help in studying ancient climates – Thickness of rings = how much precipitation in a place Each Ring = 1 year Trees live for many years. 3. Pollen Records: Find pollen fossils – Tells scientists what types Of plants lived in certain areas many years before. This gives Clues as to what climate was like. 4. Ice Age or Glacial Episode – Cold period in history 4 major ice ages in the last 2 million years They last 100,000 years or more. 5. During each ice age, huge sheets of ice called glaciers covered large parts of Earth’s surface. 6. Effects of Ice Age: *Sea level was much lower than it is today. *When glaciers melted they flooded coastal areas. *Glaciers formed many large lakes. 7. 3 Main Hypothesis for major climate changes: 1. Variations in the position of Earth relative to the sun 2. When glaciers melted they flooded coastal areas 3. Glaciers formed many large lakes. 8. Sun Spots: Dark, cooler regions on the surface of the sun.