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GEO1020 > Ice sheets, ice caps and extra-terrestrial ice > Flashcards

Ice sheets, ice caps and extra-terrestrial ice Flashcards

1
Q

What is the biggest contributor to sea level rise?

A

Glaciers

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2
Q

How much ice covers Greenland?

A

2.8 million km2

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3
Q

How thick is the Greenland ice?

A

Up to 3km thick

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4
Q

Where has the snow accumulated in Greenland?

A

In the centre

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5
Q

Where is ice being lost in Greenland?

A

At the margins

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6
Q

Why could Greenland and Antarctica be exploited?

A

For their mineral resources

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7
Q

Why hasn’t Antarctica been exploited for minerals?

A

It is protected by the Antarctic Treaty

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8
Q

How long until the Antarctic Treaty expires?

A

30 years

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9
Q

What is a problem that Greenland faces?

A

Trade routes are opening up through the country

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10
Q

What do outlet glaciers do?

A

They move ice from the centre to the oceans

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11
Q

What can be used to find the fast moving channels from outlet glaciers?

A

Remote sense data

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12
Q

What do channels transmit?

A

Climate change back inland

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13
Q

At what rate is Greenland losing ice?

A

At an increasing rate

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14
Q

Give an example of an outlet glacier with an ice tongue

A

Petermann glacier

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15
Q

Give an example of a tidewater glacier

A

Helheim glacier

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16
Q

By what two mechanisms is ice being lost in Greenland

A

Surface mass balance

Accelerated discharge

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17
Q

By what percentage does surface mass balance cause ice loss?

A

60%

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18
Q

By what percentage does accelerated discharge account for ice mass?

A

40%

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19
Q

What is surface mass balance?

A

Snow in, ice out

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20
Q

What has been seen in Greenland in recent years?

A

Accumulation has slightly increased in the centre however, the ablation on the margins outweighs this effect

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21
Q

In what year was the first year on record that there was melt across the entirety of the ice sheet?

A

2012

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22
Q

What is accelerated discharge from?

A

Outlet glaciers

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23
Q

What is accelerated discharge?

A

This is where more ice is lost through discharge

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24
Q

Which area of Greenland experiences more ice loss from accelerated discharge?

A

The North West

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25
Q

What is a good example of accelerated discharge?

A

Jakobshavn Isbrae in W greenland

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26
Q

For what percentage of overall discharge does Jakobshavn Isbrae account for?

A

6%

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27
Q

Between the 1950s and 1998 what did the Jakobshavn Isbrae do?

A

It stayed the same

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28
Q

Why was there a change in Jakobshavn Isbrae?

A

Warmer ocean waters reached the glacier

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29
Q

What happened to Jakobshavn Isbrae after the change?

A

Rapid retreat at the front of the glacierand velocity increase

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30
Q

What is the immediate response when outlet glaciers change?

A

Ice speed inland speeds up after ice berg is lost, causing the glacier to thin

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31
Q

What sort of time scale is dynamic thinning?

A

Long term

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32
Q

Why is dynamic thinning long term?

A

It takes a while for the ice to adjust

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33
Q

How is ice loss variable?

A

It is spatially variable

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34
Q

Give a brief explanation of areas of Greenland that have retreated

A

Early 2000s SE retreated, then stopped and the N started to retreat.
From 2010 onwards SE was variable but N continued to retreat

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35
Q

What 3 things have caused changes in Greenland?

A

Atmospheric warming
Sea ice
Oceanic warming

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36
Q

What can air temperatures cause?

A

Hydrofracture

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37
Q

What is hydrofracture?

A

Water flows into the crevasse and presses down on it causing it to go deeper and deeper. In addition the water melts the crevasse at its sides.

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38
Q

What happens if hydrofracture occurs at the terminus?

A

An iceberg could break off

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39
Q

What does sea ice do?

A

In the winter it sticks together icebergs from the glacier to create a mini ice shelf, causing the icebergs to be stuck. When the sea ice melts. the icebergs move

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40
Q

Which type of warming is more efficient at melting ice: oceanic or atmospheric?

A

Oceanic warming is more efficient at ice melt

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41
Q

What does ocean warming cause?

A

Submarine melting

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42
Q

What is submarine melting?

A

Where the water in contact with the ice causes it to melt

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43
Q

What is another way in which oceanic warming can cause ice to melt?

A

Melting can occur along the face of the glacier, it cuts into the glacier causing ice to fall off of it

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44
Q

What was originally thought to be the main reason for ice retreat?

A

Atmospheric warming

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45
Q

What was Zwally’s idea?

A

Lakes on the ice could drain, leading to water on the bed of the glaciers, as a result the ice speeds up bringing it to warmer climates (lower elevations) causing it to melt quicker

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46
Q

What has more research shown about hydrological system that disproves Zwally?

A

The hydrological system under the glacier evolves overtime, putting a break on the feedbacks.
Glaciers that have retreated more rapidly have ended in the oceans- so probably something in the oceans has caused the increase

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47
Q

Which current has led the oceans around Greenland to warm?

A

The North Atlantic current

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48
Q

How has the North Atlantic current led to warming and loss of sea ice?

A

The temperature of the current has changed as well as its proximity towards the glaciers

49
Q

Explain the mass balance of Greenland

A

It is gaining mass at high elevations because moist air can hold more water
Melt at low elevations is increasing over time
Very negative mass balance

50
Q

What type of ice loss has longer term effects?

A

Glacier acceleration

51
Q

What can cause outlet glacier retreat?

A

Submarine melting due to ocean warming
Reduction in sea ice
Thinning due to increased melting
Hydrofracture of crevasses

52
Q

What are the two Antarctic ice sheets?

A

West Antarctic Ice Sheet

East Antarctic Ice Sheet

53
Q

Which Antarctic ice sheet is bigger?

A

The East Antarctic Ice Sheet

54
Q

What is the potential sea level rise for East Antarctica?

A

53 m

55
Q

What is the potential sea level rise for West Antarctica?

A

3.3m

56
Q

What separates the two Antarctic ice sheets?

A

The Transantarctic Mountains

57
Q

Which Antarctic ice sheet is more stable?

A

The East Antarctic Ice Sheet

58
Q

Why is the East Antarctic Ice Sheet more stable?

A

Due to its bed- the topography is above sea level

59
Q

Why is the West Antarctic Ice Sheet more vulnerable?

A

Because it is a marine based ice sheet

60
Q

What is meant by marine based ice sheet?

A

Its bedrock topography is below sea level

61
Q

Why are marine based ice sheets vulnerable?

A

A series of feed backs can be set off, causing rapid ice loss

62
Q

Is Antarctica losing or gaining ice?

A

It is losing ice

63
Q

How is Antarctica losing ice?

A

Through surface mass balance and accelerated discharge

64
Q

What are ice streams?

A

Fast flowing corridors that are not constrained by the bedrock topography

65
Q

How much ice was lost at the Larsen B ice shelf on the Antarctic Peninsula in 2002?

A

3250 km2

Prior to this it had been in place for about 12,000 years

66
Q

What are the causes of ice loss in the Antarctic Peninsula?

A

Unsure- could be ocean warming

67
Q

What has been seen in recent years at the Antarctic Peninsula?

A

Collapse of its ice shelves

68
Q

What are ice shelves?

A

Areas of floating ice that float out over the ocean

69
Q

Why doesn’t losing ice shelves contribute to sea level?

A

They are already floating

70
Q

What happens when ice shelves are removed?

A

The glaciers in land start to move a lot quicker because the ice shelf is not there to hold it in plaece

71
Q

What is the limit of viability for ice shelve to survive?

A

Below -9 degrees C

72
Q

What might happen to Larsen C ice sheet and why?

A

It is on the temperature limit of viability so it might go

73
Q

Name two glaciers in the Amundsen Sea, Antarctica

A

Pine Island

Thwaites

74
Q

What is the issue with Pine Island and Thwaites? (4)

A

They flow quickly at 4km a year
They drain about 5% of Antartica (that’s a lot)
Huge amount of ice discharge
Rapid retreat in recent years

75
Q

What might’ve caused the issues seen by Pine Island and Thwaites?

A

Ocean warming

76
Q

What is an issue with the bed of Pine Island and Thwaites?

A

Their bed slopes downwards inland and goes below sea level, causing marine ice sheet instability.

77
Q

What happens as a result of marine ice sheet instability?

A

A series of feed backs. The glacier will retreat into areas of deeper bedrock and will not stop until it reaches a slope upland

78
Q

What would happen to sea level rise if the Pine Island and Thwaites glaciers experienced marine ice sheet instability and collapsed?

A

Sea levels would rise by 1.5m

79
Q

What is the Siple Coast also known as?

A

The Ross Sea sector

80
Q

What is happening to the mass balance at the Siple Coast?

A

It has a positive mass balance and is not discharging much ice

81
Q

Why does the Siple Coast have a positive mass balance?

A

The glaciers switch on and off all of the time

82
Q

Why do the glaciers switch on and off at the Siple Coast?

A

To do with the type of sediment and whether it is frozen or thawed

83
Q

What indications show that East Antarctica might be less stable than thought?

A

There are some changes in terms of glacier retreat and advance in this region- could be responding to some degree to climate change and the Southern Annular Mode

84
Q

What is the Southern Annular Mode?

A

This is an atmospheric phenomenon around Antarctica

85
Q

What is the temperature limit for ice shelves?

A

-9 degrees C

86
Q

By how much will the Arctic contribute to sea level by 2100?

A

19-25cm by 2100

87
Q

For what percentage of sea level rise could Arctic ice caps and glaciers contribute to?

A

35%

88
Q

What happened to the Arctic between 2011-2015?

A

It was warmer than anytime since 1900

89
Q

Which area of the Arctic is losing ice fastest?

A

Canadian Arctic followed by Alaska

90
Q

What do Arctic ice caps have?

A

Surge type glaciers

91
Q

What do surge type glaciers do?

A

Neither move slow or fast

They oscillate through two phases

92
Q

What makes glaciers slow (look at mass balance)?

A

Small amount of mass coming in and out

93
Q

What makes glaciers fast (look at mass balance)?

A

Large amount of mass coming in and out

94
Q

What are the two phases of surge type glaciers?

A

Surge phase

Quiescent phase

95
Q

What is the surge phase? (surge type glaciers)

A

Fast

96
Q

What is the quiescent phase? (surge type glaciers)

A

Slow

97
Q

How long does the surge phase last? (surge type glaciers)

A

1-10 years

98
Q

How long does the quiescent phase last? (surge type glaciers)

A

10-100 years

99
Q

What are surge-type glaciers independent of?

A

They cycle independent of climate changes

100
Q

What happens to the thickness of the glacier when it is in its quiescent phase?

A

It builds up and gets thicker

101
Q

What happens to the thickness of the glacier when it is in its in its surge phase?

A

It is thin as it chucks out all of the snow downhill

102
Q

What triggers the surge phase? (3) (surge type glaciers)

A

Changes in thermal properties
Changes in basal hydrology
Changes in sediment at the bed

103
Q

What is the cryosphere on Mars similar to?

A

That of Earth

104
Q

Where is ice located on Mars?

A

It has polar ice caps at the poles

105
Q

How extensive is the ice at the North Pole of Mars?

A

1000km diameter, 2km thick

106
Q

How extensive is the ice at the South Pole of Mars?

A

350km diameter, 3km thick

107
Q

What are the two forms of ice on Mars?

A

Water

CO2 ice

108
Q

Why is there CO2 ice on Mars?

A

It is so cold on Mars that CO2 can be frozen

109
Q

What does the CO2 ice do during the winter?

A

It creates a veneer of CO2 that expands over winter

110
Q

Why is it important for us to locate ice on Mars and its properties? (2)

A

To determine climate history of Mars

For information about water

111
Q

Where could there be life on Mars?

A

Under the ice

112
Q

What are GLFs ?

A

Glacier like forms

113
Q

Where can GLFs be found?

A

Mars mid-latitudes (30-60 degrees)

114
Q

What type of ice do GLFs have?

A

Water

115
Q

What do GLFs do?

A

They flow

116
Q

What features do GLFs have?

A

Crevasses

Moraines

117
Q

How many GLFs are there on Mars?

A

1300

118
Q

What do GLFs tell us about Mars?

A

Climate history and where water and life might be found

GEO1020 (16 decks)

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