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Paper 2: Environmental Processes and Change > D: The Cryosphere > Flashcards

D: The Cryosphere Flashcards

1
Q

How much did ice sheets loose from 1992-2002

A

7560bn tonnes

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2
Q

Ice sheet contribution to sea level rise from 1992-2002 (Otosaka, 2023)

A

21mm
2/3 due to GrIS
1/3 due to AIS

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3
Q

How many of the worst melting years have occurred in last decade (Otosaka, 2023)

A

7

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4
Q

How much sea level rise are ice sheets responsible for

A

25%
5x what is was 30 years ago
Latest evidence comes from IMBIE

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5
Q

What was the worst year for ice sheet melting (Otosaka, 2023)

A

2019
612bn tonnes
444bn attribtued to heat wave in Arctic

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6
Q

Where is most melting in Antarctica happening (Otosaka, 2023)

A

Peninsular region and West where ice margin is being eaten away from beloe by warm oceaan

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7
Q

How much SLR have ice sheets been contributing to per year (Otosaka, 2023)

A

3mm/yr

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8
Q

What is the potential SLR of the East Antarctic Ice Sheet (Luhn, 2023)

A

52m
- it is beginning to melt

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9
Q

Example of the first melted glacier on the EAIS (Luhn, 2023)

A

Conger Glacier
- first ice shelf on record to collapse in 2022

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10
Q

When was the EAIS found to be gaining mass overall (Luhn, 2023)

A

2012
- Comes from satellite gravimetry estimates from King, 2012

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11
Q

Where contains 4/5 of world ice (Luhn, 2023)

A

EAIS

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12
Q

Why is EAIS more important to SLR than WAIS (Luhn, 2023)

A
  • 52m SLR vs 3-4m SLR
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13
Q

What has sea ice extent around AIS now dropped below (Luhn, 2023)

A
  • 2 million sq km
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14
Q

What tradiaonally prevented AIS from melting (Luhn, 2023)

A
  • Circumpolar winds and ocean currents isolating it
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15
Q

What was the Antarctic heat wave like in 2022

A
  • 39 degrees higher than av temp in March 2022
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16
Q

Example of mapping effors of AIS

A
  • 2008 Siegert et al organised Icecap and Icecap 2 projects to fly over 150,00 sq km (not 14m km2)
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17
Q

Limitations of understanding AIS impacts

A

Only 23% of ocean floor on East Antactica is mapped
- Problem as ocean troughs are key to undestanding SLR as they can allow warm water to flow under continental shelves to melt ice shelves such as the Denman Glacier

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18
Q

What is the Arctic getting (Amos, 2022)

A

Wetter
- 10-15% since 1950

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19
Q

Limitations of understanding snowfall and precipitation in the Arctic (Amos, 2022)

A
  • Spareness of minirtoing stations
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20
Q

Impact of warming tempertures on Arctic (Amos, 2022)

A
  • More moisure evaporating from ocean which will precipitate out and show up as snow or rain
  • Less albedo, leading to further evaporation and precipiation
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21
Q

Define cryospehre (IPCC, 2021)

A
  • The components of the Earth system at and below the land and ocean surface that are frozen
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22
Q

IPCC comment on anthropogenic impacts (IPCC, 2021)

A
  • “It is very likely that human influence contributed to these reductions”
  • “Human-caused global warming is the dominant driver of this observed decline”
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23
Q

Contributions to sea level rise from 1971-2018 (IPCC, 2021)

A
  • Thermal expansion = 50%
  • Glaciers = 22%
  • Ice sheets = 20%
  • Changes in land-water storage = 8%
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24
Q

Define permafrost

A
  • The components of the Earth system at and below the land and ocean surface that are frozen.”
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25
Q

Must know IPCC quote (IPCC, 2021)

A

“The cryospehre is undergoing rapid changes, with increased melting and loss of frozen water mass in most regions”

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26
Q

What is permafrost defined by

A

Temperature, not ice cover

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27
Q

What do AIS and GrIS contain

A

> 99% of all land ice
68% of freshwater

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28
Q

Impact of ice sheet melt globally (IPCC, 2021)

A
  • Enough SWE to raise sea level by 65m
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29
Q

What causes imbalances in ice sheet volume

A

Imbalances between accumulation and ablation

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30
Q

Define mass balance

A

Difference beween accumulation and ablation

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31
Q

Major contributor to accumulation

A

Snowfall

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32
Q

GrIS area (Ringot et al., 2011)

A

1.7m km2

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33
Q

GrIS volume (Ringot et al., 2011)

A

3 m km3

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34
Q

SLE of GrIS (RIngot et al., 2011)

A

7.4m

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35
Q

Volume of AIS (Ringot et al., 2011)

A

30m km3

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36
Q

SLE of AIS (Ringot et al., 2011)

A

60m

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37
Q

Where do ice sheets mostly loose mass

A

Marine terminating glaciers or ice streams

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38
Q

Example of an ice tounge where a floating secion has passed the grounding line

A
  • Peterman Glacier Ice Tougne in NW Greenland
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39
Q

Example of an ice shelf melted

A

Larcen C ice shelf, Antarctic Peninsular
A38A broke away in 2017 and completely melted by 2021

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40
Q

How are ice sheets measured (van Kampenhout et al., 2020)

A
  1. Input output method
  2. Satellite altimetry
  3. Gravimetry
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41
Q

How does input-output method work (van Kampenhout et al., 2020)

A
  • Need to know suface mass balance which is calculateed using a climate mass balance model or renalsyis which calculates patterns of accumulation and runoff
  • Velocity is caluclated which provides detail in the flux of ice across grounding lines. This is done through ffeature tracking of optical images, speckle tracking of SAR images or inSAR
  • The depth of the ice sheet is calulates from an airbourne radar
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42
Q

What did Joughin et al., 2017 do

A
  • Tracked the velicty of ice sheets using opitcal imagery, SAR images and InSAR
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43
Q

Accuracy of InSAR

A
  • cm
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44
Q

Main limitation of using InSAR to measure velocity

A
  • Good where there is little change but not good when there is lots of movement which will happen more due to climate change
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45
Q

Example of altimeter

A

CryoSat2

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46
Q

What is satellite altimerty (Moholdt, 2011)

A
  • Using satellites to measure surface elevation by taking measuremnts of difference to calculate height change
47
Q

How is feature tracking achieved

A

MODIS or LandSAT

48
Q

How is gravimetry done

A
  • GRACE Satellites 220km apart measturing the gravitational field directly
49
Q

Limitations of gravimetry

A
  • Limited spatial res of 50,000km2
  • Montly temporal res
  • Has to account for isostatic adjustment
50
Q

GrIS trends from 1972-80

A

Mass gain of 47 Gt/yr

51
Q

GrIS trends from 2010-18

A

Mass loss of 80 Gt/yr

52
Q

How much SLR has GrIS caused since 1972

A

14mm

53
Q

How much has GrIS mass loss increased in the last decade

A

6x

54
Q

At what rate is GrIS thinning

A

9.84m/yr

55
Q

How much ice loss did GrIS have in 2020

A

600 Gt
- 142% higher than equillibirum level

56
Q

At what rate is GrIS loosing ice

A

261 Gt/yr (NASA, 2020)

57
Q

How much SLR did GrIS contribute to in 20th century

A

25mm

58
Q

Example of glacier in GrIS that gained mass up to 1990 before losing it

A

Helheim glacier

59
Q

What has GrIS caused

A

1/3 of global sea level rise since 1993

60
Q

Causes of GrIS causing SLR

A
  • changes in atmospheric circulation
  • 2019 had highest runoff since 1948
  • Natural variations
  • Albedo
  • Enhanced melt
  • Faster velocity
61
Q

Antarctica rate of loss

A

150 Gt/yr (NASA, 2023)

62
Q

What is biggest threat of AIS in future

A

WAIS melting
Especially vulnerbale is the Thwaites Glacier

63
Q

Under SSP8.5 how much SLR will GrIS cause (Hofer et al., 2020)

A

Up to 0.18m

64
Q

Under SSP8.5 how much SLR will AIS cause (Hofer et al., 2020)

A

Up to 0.34m

65
Q

GrIS contribution to SLR in early 20th century (IPCC, 2001)

A

0.1mm/yr

66
Q

GrIS contribution to SLR in late 20th centiry (IPCC, 2001)

A

0.23mm/yr

67
Q

GrIS contribution to SLR in early 21st century (IPCC, 2019)

A

0.69mm/yr

68
Q

GrIS contribution to SLR in 2023 (IPCC, 2019)

A

0.77mm/yr

69
Q

GrIS contribution to SLR under SSP8.5 by 2050 (IPCC, 2019)

A

0.88mm/yr

70
Q

GrIS mass sheet loss in late 20th century (IPCC, 2001)

A

83 Gt/yr

71
Q

GrIS mass loss in early 21st century (IPCC, 2019)

A

248 Gt/yr

72
Q

GrIS mass loss in 2023 (IPCC, 2019)

A

279 Gt/yr

73
Q

GrIS mass loss by 2050 under SSP8.5 (IPCC, 2019)

A
  • 317 Gt/ur
74
Q

AIS mass loss in late 20th century (IPCC, 2001)

A

91 Gt/yr

75
Q

AIS mass loss in early 21st century (IPCC, 2019)

A
  • 182 Gt/yr
76
Q

AIS mass loss in 2023 (IPCC, 2019)

A

151 Gt/yr

77
Q

AIS mass loss by 2050 under SSP8.5 (IPCC, 2019)

A
  • 183 Gt/yr
78
Q

AIS SLR in early 20th century (IPCC, 2001)

A

0.2mm/yr

79
Q

AIS SLR in late 20th century (IPCC, 2001)

A
  • 0.27mm/yr
80
Q

AIS SLR in early 21st centiry (IPCC, 2019)

A
  • 0.50mm/yr
81
Q

AIS SLR in 2023 (IPCC, 2019)

A

0.43mm/yr

82
Q

AIS SLR by 2050 under SSP8.5 (IPCC, 2019)

A

0.51mm/yr

83
Q

When was AIS losing more mass than GrIS

A

Late 20th century
91 Gt/yr vs 83 Gt/yr

84
Q

Current disparity between GrIS and AIS

A

GrIs losing more
279 Gt/yr vs 151 Gt/yr
0.77mm/yr vs 0.42mm/yr

85
Q

Late 20th century (IPCC)

A

GrIS - 83Gt/yr, 0.23mm/yr
AIS - 91Gt/yr, 0.27mm/yr

86
Q

Early 21st centry (IPCC)

A

GrIS - 248Gt/yr, 0.69mm/yr
AIS - 182Gt/yr, 0.50mm/yr

87
Q

2023 IPCC

A

GrIS - 279Gt/yr, 0.77mm/yr
AIS - 151Gt/yr, 0.42mm/yr

88
Q

2050 IPCC SSP8.5

A

GrIS - 317Gt/yr, 0.88mm/yr
AIS - 183Gt/yr, 0.51mm/yr

89
Q

Define sea ice

A

Ice on the sea surface that has originated from the freezing of seatwaer

90
Q

Where is sea ice found

A

Polar regions, the Arctic ocean and the Southern Ocean

91
Q

What % of Earth’s surface does sea ice cover

A

7%

92
Q

How is sea ice catergorised - 2 ways

A

According to its age
Whether it can drift

93
Q

Ages of sea ice

A

New ice
Nilas
Young ice
First year ice
Perennial ice

94
Q

What are polynas

A

A polynya is an area of open water surrounded by sea ice.

95
Q

How is ice categorisedd by whether it can drift

A

Fast ice - fastened to the shoreline
Drift ice - free to move with wind and currents, ranging from small to giant

96
Q

How can sea ice be calculated

A

Early data
Satellites
Reanalysis
Modelling

97
Q

Early data for sea ice

A
  • Written records
  • Ice records
  • Shipping routes
  • Submarine sonar
  • Whaling records
  • Ship log books
  • Proxies
98
Q

Satellite data for sea ice

A
  • SMMR on Nimbus7 and SeaSat
  • Compiled data sets such as NASA Team or BootStrap
  • Can measure thickness with altimeters by looking at height above freeboard. ICESAT altimeter or Cryosat2 radar altimeter
  • 25km spatial res
99
Q

Reanalysis for sea ice

A
  • PIOMass Assimilation System
  • Assimilation of model and surface temperature data
  • Ocean Renalaysis Interc
  • Looks at SIA
100
Q

Modelling sea ice

A

Notzetal, 2016
- Sea ice model intercomparison project (SIMIP)
- Poor in capturing SIA in Antarctica - do not capture observed spatial distribution and poor evaluation of sea ice thickness
- Ocean-atmosphere interactions unknown
- Observed data limited
- Albedo challenging to model accurately
- Local challenges such katabatic winds and coastal polynas
- Complex feedbacks

101
Q

Sea ice change in Arctic

A

-13% per decade from Sept 1979-2018 (IPCC, 2021)

102
Q

How much smaller is sea ice in Arcic in 2010-19 vs 1979-88

A

25% smaller

103
Q

How much thinner is sea ice

A

72% thinner

104
Q

When is sea ice min and max

A

Min in Sept
Max in March

105
Q

What % of loss are anthropogenic forcings responsible for

A

1/2

106
Q

What is less common

A

Multi-year sea ice
33% in 1985
1.2% in 2019

107
Q

What is happening to Antarctic sea ice

A

Not much - little net change
Increase in Weddel and Ross Seas
Decrease in Amundson and Bellingshausen seas

108
Q

Conflict between models on Antarctic sea ice

A

Renalsis shows increase in thickness whereas models show a decrease

109
Q

What will the Arctic be by 2050

A

Sea ice free
For all SSPs
Reducing from 2mkm2 to under 1mk2 for SSP8.5

110
Q

What is sea ice loss

A

Reversible
No tipping points
Negative feedbacks dominate over positive feedbacks

111
Q

Arctic amplification

A

Artic projected to increase by 3-12 C by 2100

112
Q

Summarise Karakoram Anomaly

A

Karakoram mountain range gaining glacier

113
Q
A

Paper 2: Environmental Processes and Change (6 decks)

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