1. So How is this linked to last lesson?
HW Answer
The Thames regularly froze in the past!
So How is this linked to last lesson?
The Thames no longer freezes like this so indicates we are in a warmer period!
Feb 1814 was one winter famous for its frost fares!

2. Global Temperature Change
Key Question: What other evidence do geologists have for temperature change?
Key Words:
Ice Cores
Tree Rings (Dendrochronology)
Pollen Analysis
Deep Sea Sediments

3. Other evidence for temperature change
LISTEN TO THE FOLLOWING OTHER EVIDENCE CAREFULLY……..
You will need it in a later task

4. Ice Core Analysis Recent decades coring of polar glaciers/ice sheets.
Cores  represent annual increments of frozen precipitation.
Drilling of 2 cores to bedrock in the thickest Part of the
Greenland ice sheet (>3km thick) by:
American Greenland Ice Sheet Project (GISP 2)
European Greenland Ice-Core Project (GRIP)
Provided evidence of scale, speed and how often the
temperature changed

5. Ice Core Analysis Annual Ice Increments
(equivalent to calendar years, clarity diminishes with depth)
Air Bubbles: Contain CO2 and Methane and stable
isotopes
Winter layers – light
Summer Layers - dark
Biological Material: Microbe/fungal spores/pollen
Dust Content
Evidence of aeolian activity, Volcanic Dust
Chemical Content
Provides record of past volcanic activity
Type of Oxygen either heavy or isotopically lighter – 18O:16O
Provides evidence of past surface ocean temperature.

6. Summer Layers
Winter Layers

7. Pollen Analysis Most versatile technique
When plants releases spores, some may become preserved in sediments
Plant species require particular climatic requirements which influence their geographic location.
Pollen can therefore reveal information about vegetation changes through time and indirectly climate.

9. Dendrochronology Trees growing N/S of equator grow 2 bands
Spring Bands – Wider (rapid growth)
Autumn/Winter – Narrower (slower growth)
Wider rings = more rapid growth indicating warmer conditions
Change in the width most important from year to year as trees often grow wider rings in early years.

10. Winter
Summer

11. Deep Sea Sediments
Provide a complete record of micro-fossil evidence diatoms and forams
The type/distribution of the microfossils present indicate the climatic conditions that prevailed during their existence.

12. Now have a go yourselves at completing the evidence for temperature change worksheet