Quaternary Climate Change

Question 1

What are the three characteristics defining Quaternary?

Answer 1

1. Climate change (landscape evolution)
2. Evolution of humans and society
3. Up to and including today.

Question 2

What are natural archives?

Answer 2

They are records of global climate and environmental change (for the past 800,000 years).

• atmospheric CO2
• tropical sea surface temperature
• Antarctic temperature
• deep ocean temperature (and ice volume)
  eustatic sea level.

All these have a regular rhythm but with some surprises.

Question 3

What do perihelion and aphelion mean?

Answer 3

The sn is not at the elliptical centre of Earth’s orbit:

Perihelion = when the sun is the closest to Earth
Aphelion = when the sun is furthest away from the Earth

Question 4

What are the three main orbital parameters?

Hint: from milankovitch (1930)

Answer 4

1. Eccentricity of Earth’s orbit
   (varies from near circular to more elliptical at cycles of 100,000 years.
2. Tilt of Earth’s axis
   (axial tilt varies from 24.5-22.1o at cycles of 41-42,000 years.
3. Precession (of equinoxes)
   (not changing tilt but the direction of time - alters the time of the year when Earth is closest to the sun).

Question 5

What are the main points during a glacial, Quaternary period?

Answer 5

1. Antarctica was slightly bigger
2. The northern hemisphere had a lot more glaciers
3. Sea levels change
4. Drier conditions in glacial winds.

Question 6

What is the maximum and minimum tilt of Earth?

Hint: 2nd orbital parameter

Answer 6

Minimum = 0 degrees means no seasons. 
Present = 23 degrees and allows for seasons.
Maximum = 60 degrees means there will be extremes in climate.

Question 7

What does eccentricity alter?

Hint: 1st orbital parameter

Answer 7

Alters the length of seasons.

Question 8

What does precession alter?

Hint: 3rd orbital parameter

Answer 8

Alters the time of the year when Earth is closest to the sun.

Question 9

What does obliquity alter?

Hint: 2nd orbital parameter

Answer 9

Alters spatial and seasonal distribution of insolation.

E.g. Tropics vs poles.

Question 10

What was the key to ice age (dominant in the Southern Hemisphere)?

Answer 10

Is summer insolation in high northern latitudes, 60o north.

Harder to build ice on land (e.g. Northern Hemisphere) and easier to melt ice off the land too.

Question 11

What are stable isotopes?

Answer 11

Have a constant volume in Earth System (e.g. 14C is unstable - decays).

Question 12

What is the principle of oxygen isotope stratigraphy?

Answer 12

Warmer climate = ocean 16O is high.
Colder climate = ocean 16O low and 16O in ice is high.

This is because the water containing the 16O has frozen trapping and stopping the supply of 16O in the ocean.

So, in an ice age the supply of 16O is cut off.

Question 13

Why is 16O and 18O found where they are found (not during an ice age)?

Answer 13

16O is lighter so circulates while 18O is denser and only found in the ocean.

Question 14

what are some key characteristics of Foraminifera in marine sediments?

Answer 14

1. Abundant marine microfossils
2. Species composition reflect living conditions (temperature reconstruction)
3. Calcareous shells reflect the chemistry of the ocean.

Question 15

What can be taken away from the past about climate change?

Hint: Steps

Answer 15

1. Orbital and solar variations
2. Variation in Earth’s insolation regime over time
3. Internal climate system (ice sheets, sea level, ocean and atmospheric circulation, Greenhouse gases, albedo, volcanism, biosphere).
4. Equals climate change

Note: steps 1 and 2 are EXternal forces and the rest are internal.