L5 - Millennial Scale Climate Change (Records)

Question 1

Before Greenland Ice Cores what did we know with regards to paleoclimate?

Answer 1

The major G-IG changes

Question 2

What did early records from the Greenland ice cores tell us?

Answer 2

That there was high frequency and high variability in the glacial but it was difficult to tell if this was actually the case or if the changes were a result of local deformation

Question 3

Repeated records in Greenland showed and prompted what?

Answer 3

Showed that the variability was real and prompted the start of getting a global record of variability

Question 4

Which location in Greenland first gave evidence of abrupt/dangerous climate change?

Answer 4

Summit

Question 5

What can be used as a temperature proxy to show larger variations?

Answer 5

Nitrogen-15

Question 6

What is a D-O event?

Answer 6

Rapid warming (>10degC) followed by gradual cooling

Question 7

What is a Stadial?

Answer 7

Millennial scale (hemispheric) cold episode

Question 8

What is an Interstadial?

Answer 8

The warm period between 2 stadials

Question 9

What is the periodicity for D-O events?

Answer 9

~1470 years

Question 10

Give 3 other records we have from ice-cores

Answer 10

1. Stadial periods are much more dusty
2. Snow accumulation is higher during the interstadial
3. Large shifts in atmospheric methane match shifts in temperature

Question 11

What 3 pieces of evidence do we have from North Atlantic sediments?

Answer 11

1. SST records showing an in-phase relationship with Greenland
2. Heinrich layers rich in IRD
3. Bond Cycles (pockets of D-O events) bind Heinrich Events

Question 12

How can global evidence help us?

Answer 12

It can help tell us about the mechanisms even though the variability is different

Question 13

What pieces of global evidence do we have?

Answer 13

1. SST records from the Santa Barbara Basin showing an in-phase relationship with Greenland and evidence of abrupt climate change
2. Laminated Sediments from the Cariaco Basin suggesting dryer conditions in the stadials and a southwards shift of the ITCZ
3. Speleothems showing weaker Asian monsoons in the stadial and a stronger South American monsoon
4. Marine Records from the Arabian Sea showing upwelling in the interstadial
5. Mediterranean Pollen Records showing tree populations have been diminished and increased tundra during the cold events

Question 14

What evidence do we have from the Deep Sea?

Answer 14

What a low C-13 causes the AMOC to shoal preventing Northern sourced water from reaching the deep waters and that there is reduced transport of magnetic sediments doing stadials and H-events

Question 15

What is the Antarctic Climate Signal?

Answer 15

Antarctica warms when Greenland is cold and cools when Greenland is warm

Question 16

What is the (thermal) bipolar seesaw hypothesis?

Answer 16

The inverse relationship between Greenland temperatures and the rate of change in Antarctic temperature can be used to predict one signal from the other

Question 17

What happens in the deglacial period?

Answer 17

They are large, rapid and extreme. There is a strengthening in the AMOC and an increase in CO2