L7 - The Holocene

Question 1

The Holocene is Stage 1 covering which years?

Answer 1

10,000 years ago to the Present

Question 2

What was the 8.2kyr event?

Answer 2

The largest amplitude event in the Holocene

Question 3

Sub-Orbital timescales are what timescales?

Answer 3

Millenial

Question 4

How much higher is SL that it was at the LGM?

Answer 4

120m

Question 5

What are the 2 main drivers for Eustatic SL change?

Answer 5

1. G-IG Melt

2. Thermal Expansion

Question 6

Which sea was flooded at the end of the last deglaciation?

Answer 6

The Black Sea

Question 7

Glacial rebound occurs on what timescale and where is it shown in the UK?

Answer 7

1,000s of years
The North is rising (Firth of Forth)
The South is falling (Dungess, Kent)

Question 8

What is the Climatic Optimum?

Answer 8

A dominant Northern Hemisphere Summer Event

Question 9

When was there warming in the Holocene?

Answer 9

Early (Pre 8.2 event)

Question 10

More recently (Post 8.2 event) what has the general trending temperature been in the Holocene?

Answer 10

Gradual Cooling

Question 11

Give 6 methods for evidencing Holocene temperature trends?

Answer 11

1. Greenland Ice Cores
2. European Pollen Assemblages
3. Low Latitude Ice Cores
4. Western Equatorial Pacific Forams
5. Antarctic Ice Core
6. Tropical Atlantic Forams

Question 12

What has happened to the Northern Hemisphere snowline throughout the Holocene?

Answer 12

It has lowered

Question 13

What do colder summers in the North mean for monsoons?

Answer 13

They are weaker

Question 14

What do warmer summers in the South mean for monsoons?

Answer 14

They are stronger

Question 15

What does a southwards shift of the ITCZ cause?

Answer 15

Drying in the North and increase pptn in the South

Question 16

What has happened to the ITCZ throughout the Holocene?

Answer 16

It has been shifting Southwards

Question 17

In the early Holocene, there was high obliquity which meant what?

Answer 17

Closer to the sun in summer (perihelion) – stronger summers and more seasonal contrast
(It is the opposite today)

Question 18

What dominates insolation today?

Answer 18

Precession

Question 19

In the last how many years has methane risen? and what are the 2 theories?

Answer 19

~5000 years

1. Paddy Fields
2. Natural Changes in Tropical Hydrology

Question 20

How many years have we got a well-documented rise in CO2 and what are the 2 main reasons for this when it should be falling?

Answer 20

~8000 years

1. Forset Clearance
2. Fossil Fuels

Question 21

What has the Greenland Ice Core shown about the 8.2 event?

Answer 21

Less snow accumulation, lower temperatures, winder, increased fires, decreased methane

Question 22

What have speleothem records shown about the 8.2 event?

Answer 22

Dryer in the North and Wetter in the South

Question 23

What have North Atlantic Marine Sediments shown about the 8.2 event?

Answer 23

Similarities with the Stage 3 stadial – reduced SST, reduced surface salinity, lower bottom current flow speeds

Question 24

What are the 3 centennial to millennial variabilities to occur during the Holocene?

Answer 24

1. Fluctuations in IRD (1500 year periodicity)
2. Asian Monsoon Variations (small bond events = weaker and match IRD events)
3. South American Monsoon Variations (stronger but we aren’t confident)

Question 25

When was the Maunder Minimum?

Answer 25

During the Little Ice Age

Question 26

How long are solar cycles?

Answer 26

11 years + some longer variations

Question 27

How does TSI change globally with increased sunspot activity?

Answer 27

~0.1%

Question 28

What can be used as a proxy for solar variability?

Answer 28

C-14 and Be-10 and cosmic ray intensity records

Question 29

What does a decreased TSI mean for monsoons?

Answer 29

Weaker in the Northern Hemisphere and Stronger in the Southern Hemisphere

Question 30

What does a decreased TSI mean for SST?

Answer 30

Colder SST