Chapter 7: Climate history of the earth

Question 1

Ice age

Answer 1

is a long interval of time (millions to tens of millions of years

• global tempertures are cold
• large areas of earth are covered by continental ice sheets and glaciers
• the most recent ice age began approximatly 3 millions years back and continue today

Question 2

ice age cycle

Answer 2

within ice age multiple shorter periods of warm temperature when glaciers retreats (inter glacial) and colder temperature when glaciers advance (glacial)

Question 3

Inter glacial

Answer 3

• glacial periods are much longer than inter glacial periods
  
  • glacial periods (10,000 to 90, 000 years)
  • inter glacial periods (10,000 to 30, 000 years)
• currently, we are in the interglacial period than began about 11,000years ago
• the last period of glaciation peaked about 20,000 years ago, during this period. the global average temperature was 5 c colder than today
  
  • locally as much as 22 c colder

Question 4

causes of ice age and glacial and interglacial cycles

Answer 4

• changes in ocean & atmospheric circulation patterns due to plate tectonics
• varying concentrations of atmospheric CO2
• volcanic erruptions

Question 5

glacials and inter glacials occur in

Answer 5

regular repeated cycles due to cyclic changes in earth orbital charactaristics (milankovitch oscillations)

• earths tilt
• ellepticity
• precision

Question 6

proxies will have

Answer 6

• different resolution
• give information for different periods

Question 7

climate reconstruction

Answer 7

collecting the piecewise climate information from different climate proxies

Question 8

climate indicators that can be measured from ice core samples

Answer 8

• volcanoes occured: the amount of dust (ex: volcanic debree) in each annual layer
• composition of atmosphere: the composition of air bubbles trapped in ice
• temperature: isotopic concentration of water

chronology: arrangment of data in time (200,000 years). depth: 3087 m

Question 9

stable isotope analysis

Answer 9

oxygen has 3 natural isotopes

• 18O - small amount - used for isotope analysis
  
  • 18 is the atomic mass
  • heavy isotop (more mass)
• 17O- smaller amount
• 16O - most abundant - used for isotope analysis

Question 10

difference between 16O and 18O

Answer 10

• 16O:
  
  • light
  • takes less energy to convert into vapor (can easily evaporate)
• 18O:
  
  • heavy
  • more energy
  • high if it parcel is warm
    
    • 18O/16O is also high

Question 11

a less ratio of 18O/16O when

Answer 11

an air mass moving from tropics (more precipitation) to higher latitudes

Question 12

Ocean sediments

Answer 12

• isotropic analysis
  
  • sea organisms posses shells (CaCO3) containing more heavy oxygen if the organisms live in cold water (glaciers)
• pollen analysis

Question 13

isotropic analysis

if the portion of heavy oxygen in sea shells

Answer 13

• go up in years where the temperature is colder (glacial)
• go down in years when temperature is warm (inter glacial)