Transcript W&C Ch.4 Sec.3

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.