lecture 6

Question 1

what are paleorecords

Answer 1

○ Ice core samples
§ Determine what the air in the atmosphere was like in the past
Bubbles of air in the ice that are thousands of years old

Question 2

what are fossil tree ring samples

Answer 2

§ Can core trees and take samples without harming them
§ See indications of events/conditions such as moisture, fire,
§ Carbon analysis for exact date

Question 3

how are pollen samples in sediment used?

Answer 3

○ Pollen samples in sediment - not enough oxygen at the bottom of lakes
§ - sediment makes layers that are maintained over time (few hundred to thousands of years) - can core and carbon date samples from sediment and can look at spores inside of the sediment
§ These samples show what kinds of plants were around - the community alive at that time
§ Pollen is like a snow flake - distinct for each species of plant
Can also do things with organisms

Question 4

What have we learned from paleoclimate proxies?

Answer 4

• Climate is inherently variable over all time scales (natural variation)
  
  • What does this mean for climate change?
    ○ Must b viewed as overlays on natural climate variability

Question 5

interannual climate variability?

Answer 5

el nino and la nina

Question 6

how can we tell when interannual climate variability occurs?

Answer 6

• El nino, southern oscillation (ENSO)
  ○ IF you take a longer term measurement of average temp. variation you can see the mean values
  ○ In an El nino year you see more warmth in equator
  In la nina years you see nearly an opposite pattern -

Question 7

how does el nino interact? when does it happen?

Answer 7

• Air-sea interaction, couples:
  ○ Atmosphereic pressure changes
  ○ Changes in ocean temp. over pacific ocean
  
  • Every 3-7 years (irregular)
    We don’t really know how to exactly predict the cycles/oscillation events - the exact years aren’t known

Question 8

describe la nina effects

Answer 8

• Easternly trade winds push warm surface waters of the pacific westward
  
  • Warm surface water deeper in western pacific than east; associated with high rainfall in the west
  • Strong thermocline - cold water to the bottom reaches the top- cycling
  • Cold water is nutrient rich - upwelling
    High pressure areas concentrated around the upwelling - cycles down

Question 9

describe el nino effects

Answer 9

• Pressure centers and trade winds weaken
  
  • Warm surface waters move eastward, forming deep layer of warm surface water in eastern pacific
  • Change in pattern- exact cause unknown
  • Fisheries crash bc less upwelling
  • Reduces upwelling of cold water promoting atmospheric convection and rainfall in coastal ecuador and peru
  • Colder waters in the western pacific inhibit covection (droughts in indonesia, australia, and india)

Question 10

what are ENSO effects world wide? do we know the triggers?

Answer 10

• ENSO effects worldwide:
  ○ Droughrts in australia, indonesia
  ○ Hot dry weather in the amazon
  ○ Warm, wet winters in north america
  The trigger for changes in the ocean-atmosphere system are uncertain