Cryosphere 3- Case-studies – ice-sheet influence on ocean currents and heat transport

Question 1

What causes the release of heat from the North east Atlantic?

Answer 1

Gulf stream
North Atlantic drift

Question 2

What is responsible for heat movement to higher latitudes?

Answer 2

Atmosphere

Question 3

What is one of the main ocean drivers of the gulf stream/ North Atlantic drift?

Answer 3

Squeezing on the edge of gyre systems

Question 4

What processes cause the movement of heat to the atmosphere from the ocean?

Answer 4

Evaporation and latent heat

Question 5

What is another name for the movement of heat via the gulf stream and north Atlantic drift?

Answer 5

Thermohaline circulation

Question 6

What is thermohaline circulation?

Answer 6

when currents are driven by heat (thermo) and salinity (hals)

Question 7

Why are the surface waters of the Nordic and Labrador sea unusual?

Answer 7

they become dense enough to sink to depths below 2 km (during winter
time) sinking compensated by influx warmer equatorial water

Question 8

What is North Atlantic drift?

Answer 8

when the gulf stream extends across the Atlantic

Question 9

What is the average depth of the ocean and does wind interact with this?

Answer 9

4000m deep wind can only affect 1000m

Question 10

What does wind only affecting 1000m depth of ocean mean must be the driver of deep ocean currents?

Answer 10

varying temp and salinity and how this affects their density

Question 11

What can the movement rate of deep ocean currents be across an ocean basin?

Answer 11

decades to centuries

Question 12

What outflow adds salinity and thus increases density further driving north Atlantic drift?

Answer 12

Mediterranean (which is warm but doesn’t sit on surface due to high salinity and thus density)

Question 13

What is brine rejection?

Answer 13

when salt water freezes salt is expelled as brine

Question 14

What happens when brine is rejected?

Answer 14

drains into ocean in narrow channel due to cold and saline sinks in plume which freezes water it comes into contact with

Question 15

What was North Atlantic drift like during summer in the LGM?

Answer 15

algae records suggest warm surface water open up sea ice in Nordic sea
Deep currents for thermohaline circulation dont form

Question 16

What was North Atlantic drift like during winter in the LGM?

Answer 16

Warm surface currents and thermohaline circulation pushed south and northward heat transport is greatly reduced from 30°N

Question 17

What will happen if their is sediment instead of rock under a glacier?

Answer 17

will deform easier allowing quicker movement
Thought quaternary ice sheet margin were prone to collapse

Question 18

How do Heinrich events/ layers form?

Answer 18

Wind from Sahara can carry fine sand but not coarse sand or gravel but icebergs are the only thing that can carry larger material

Question 19

What is a H event?

Answer 19

a dramatic collapse or increase in freshwater slowing or stopping North Atlantic drift to higher latitudes

Question 20

What was N. Atlantic circulation during a H event?

Answer 20

Lid of cold freshwater laden with interrupted ocean conveyor system
Climate affected
Air passing across ice field causes temp on land to plummet

Question 21

What are Heinrich events associated with?

Answer 21

Coldest phases of last glacial and ice berg release

Question 22

What are D/O cycles?

Answer 22

rapid warming and cooling through last glacial

Question 23

What does DO cycles stand for?

Answer 23

Dansgaard-Oeschger cycles

Question 24

What is the length of the cold warm period of D/O cycles?

Answer 24

1-2kyr

Question 25

Where can D/O cycle evidence be found?

Answer 25

First in Greenland ice cores
marine and terrestrial records
intense in North Atlantic regions

Question 26

What was the younger dryas?

Answer 26

last big climatic event of the late Quaternary before the Holocene

Question 27

When was the younger dryas?

Answer 27

return towards glacial conditions 12.9 to 11.65ka

Question 28

What was the younger dryas responsible for in the UK?

Answer 28

Loch Lomond stadial

Question 29

What was the younger dryas caused by?

Answer 29

massive flow glacial meltwater in north Atlantic which restricted overturning circulation

Question 30

Where was the largest meltwater/ iceberg discharge?

Answer 30

into Arctic via NW passage

Question 31

What was the 8.2 ka event?

Answer 31

The biggest climatic event in the Holocene in the N Atlantic region

Question 32

How was the 8.2 ka event like compared to the younger dryas?

Answer 32

less severe

Question 33

What do Greenland ice cores show the 8.2ka event was like?

Answer 33

cold (less accumulation, lower d 18 O,
windy (more salts (Cl-) and dust (Ca2+ )
dry (decreased CH 4 )

Question 34

What are tipping points?

Answer 34

points in earths climate where one change can lead to uncontrolled runaway climate change