Week 7 part 2

Question 1

What does Millennial scale mean?

Answer 1

lasting for a few thousand years
• Some changes happened within decades
> Relevant to a human life span

Question 2

Where do Dansgaard-Oeschger Events occur?

Answer 2

Greenland

Question 3

Where do Heinrich Events occur?

Answer 3

North Atlantic Marine sediment

Question 4

Where do Antarctica Isotopic Maxima Events occur?

Answer 4

Antarctica

Question 5

What happens in a Dansgaard-Oeschger Event?

Answer 5

sharp spikes in d18O indicate temperature changes

of up to 15C

Question 6

How many Dansgaard-Oeschger Events over the last glacial period?

Answer 6

Over 25 events during the lastglacial period

Question 7

What is a Interstadial?

Answer 7

warmer period in otherwise cold glacial climate

Question 8

Waht is a Stadial?

Answer 8

coldest glacial conditions

Question 9

What is the pattern of Dansgaard-Oeschger Events?

Answer 9

saw-tooth shaped pattern
Abrupt warming of up to 15C
Warmer ‘interstadial’ persists for 100’s to 1000’s years
Gradual cooling
random in time and duration

Question 10

What are the characteristics of Greenland ice?

Answer 10

Long and continuous

• High resolution – sub-decadal to annual resolution
• Multiproxy
• Excellent replication between different ice cores

Question 11

What are the large ice berg discharge

events known as?

Answer 11

Heinrich Events

Question 12

How many Heinrich Events have there been?

Answer 12

6

Question 13

How are henich events recorded?

Answer 13

as layers of coarse-grained sediments derived

from the land.

Question 14

What are heinrich events evidence for?

Answer 14

Evidence of an increase in iceberg discharge and a

southward extension of cold polar waters

Question 15

How long do heinrich events last?

Answer 15

Events last between 200 and 2000 years

Question 16

what is the Relationship between Heinrich and

Dansgaard-Oeschger Events

Answer 16

Heinrich Events occurred during coldest intervals
in Dansgaard-Oeschger Events
but not every Dansgaard-Oeschger Events

Question 17

how often where Heinrich events?

Answer 17

every 10,000 years

Question 18

What is Dansgaard-Oeschger and Heinrich Events footprint

Answer 18

near global
temperature and precipitation changes in North America and Europe
monsoon variations

Question 19

What where the vegetation changes in Europe during Dansgaard-Oeschger and Heinrich Events?

Answer 19

• Repeated expansion and contraction of temperate forests

- Changes occurring over centuries

Question 20

When did the Asia summer Monsoon strengthen?

Answer 20

Asian Summer Monsoon strengthened during warming events (interstadials) in Greenland

Question 21

How are Antarctic millennial scale changes different from those in greenland?

Answer 21

smaller in size , warmings are less abrupt
Warming in Antarctica lags cooling in Greenland by ~200 years
warming in Antarctica occurred when Greenland had reached peak cold temperatures
Bipolar seesaw pattern

Question 22

Why are Antarctica and Greenland out of phase?

Answer 22

due to AMOC

Question 23

What are Antarctic millennial scale called?

Answer 23

Antarctica Isotopic Maxima (AIM)

Question 24

What does a Strong AMOC cause?

Answer 24

interstadial conditions
• Enhanced northward heat transport
• Ice sheets around North Atlantic start to
melt
• Surface salinity slowly reduces

Question 25

What does a Weak AMOC cause?

Answer 25

``` stadial conditions • Reduced northward heat transport leads to cooler conditions in the North Atlantic • Reduced meltwater • Surface salinity slowly increases ```

Question 26

What is the Underlying cause of AMOC changes?

Answer 26

changes are related to the influx of freshwater due to ice sheet melt and calving around the North Atlantic

Question 27

Why do we not see Dansgaard-Oeschger | events during interglacial periods?

Answer 27

The presence of continental ice is important | • Dansgaard-Oeschger events occur within a particular CO2 range