Climates of the past; lecture 2+3

Question 1

What are the long term geological climate change drivers?

Answer 1

• tectonic processes
• changes in teh strength of the sun
• earth orbital changes

Question 2

What was Carl Sagan’s theory of the ‘pale blue dot’?

Answer 2

• the idea that all water must be frozen in earths early history contrary to other evidence

Question 3

How are banded iron formations created?

Answer 3

• in anoxic, high CO2 atmospheres

- they are deposited in low energy aquatic environments

Question 4

What are the differences between planet Earth and Venus?

Answer 4

• More incoming solar radiation and reflection on venus
• majority of the venus’ carbon is stored in the atmosphere whereas not the case for earth
• venus has an atmosphere 90x denser than earth

Question 5

How is a long term build up of CO2 avoided?

Answer 5

• the removal of co2 by chemical weathering by silicate rocks

Question 6

How are rates of chemical weathering affected?

Answer 6

• temperature
• precipitation
• vegetation

higher values of these increases rate of chemical weathering

Question 7

Describe the negative feedback from chemical weathering

Answer 7

• increased temperature, precipitation and vegetation
• increased chemical weathering
• increased co2 removal by weathering
• reduction of initial warming

Question 8

Why are cyanobacteria important?

Answer 8

• they undergo photosynthesis which is important in the role of oxygen on the planet

Question 9

What is teh significance of lipid bilayers in this context?

Answer 9

• they preserve well in geological records whereas DNA and proteins do not

Question 10

What evidence indicates oxygenation in the early earth?

Answer 10

• banded iron formation
• sulfur isotopes
• https://open.spotify.com/track/4TOnziP6TsZ6dD7RzEVEqGcyanobacteria

Question 11

What is hydrolysis?

Answer 11

Hydrolysis is the chemical breakdown of a substance when combined with water

Question 12

What is the snowball earth?

Answer 12

• increase in chemical weathering in tropics, decreases co2
• increase in albedo effect due to ice build up
• chemical weathering stops, volcanoes don’t so co2 builds up
• warm enough to melt away ice, decrease in albedo

Question 13

What is the quaternary period?

Answer 13

• covers a period of the last 2.6 million years

- the time during which recognizable humans existed (includes the Holocene)

Question 14

What two epochs does the quaternary period include?

Answer 14

Holocene and Pleistocene

Question 15

Describe the Pleistocene

Answer 15

when modern humans evolved

extinction of mammoths and other animals in the ice age

Question 16

Describe the Holocene

Answer 16

the spread of human civilization throughout the globe

humans became the dominant form of life

Question 17

Describe the quaternary climate

Answer 17

• characterized by the periodic cycles of forming ice and decaying ice sheets (glacial and interglacial)

Question 18

What signifies a cold glacial period?

Answer 18

• a growth of ice caps
• a fall in sea levels
• a drier and dustier climate
• a shift and compression of climate zones towards the tropics

Question 19

What signifies a warmer interglacial periods?

Answer 19

• ice caps glaciers and sea ice would reduce
• sea levels would rise
• climate zones would be close to what they are today

Question 20

What is evidence of Quaternary ice ages?

Answer 20

Depositional landforms

• Erratics; large boulders different to the surrounding geology
• moraines
• fragmentary terrestrial sedimentary records e.g. till
• sedimentation in the ocean

Question 21

What drives quaternary climate?

Answer 21

-Milankovitch cycles

Question 22

What is the Milankovitch theory

Answer 22

The theory that variations in the Earth’s orbit were the primary drivers of global climate patterns. These ‘orbital forcing’ mechanisms are eccentricity, obliquity, and precession

Question 23

What is the positive feedback system of ice/albedo and temperature?

Answer 23

• climate warming
• less ice/snow = lowers reflectivity
• more solar radiation
• increased warming

Question 24

What is the positive feedback system for the carbon cycle and temperature?

Answer 24

• climate warming
• movement of carbon to atmospheric reservoir
• more long wave radiation absorbed by atmosphere
• increased warming

Question 25

What is the positive feedback of increased cooling?

Answer 25

• climate cooling
• increased snow and ice; higher reflectivity
• less solar radiation absorbed at surface
• greater cooling

Question 26

What are the impacts of glaciation?

Answer 26

• sea level fall alternating with rises when glaciers melt

Question 27

What is the eemian?

Answer 27

the most recent interglacial period of the Pleistocene in northern Europe