D: The Cryosphere Flashcards
(113 cards)
1
Q
How much did ice sheets loose from 1992-2002
A
7560bn tonnes
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
3
Q
How many of the worst melting years have occurred in last decade (Otosaka, 2023)
A
7
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
5
Q
What was the worst year for ice sheet melting (Otosaka, 2023)
A
2019
612bn tonnes
444bn attribtued to heat wave in Arctic
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
7
Q
How much SLR have ice sheets been contributing to per year (Otosaka, 2023)
A
3mm/yr
8
Q
What is the potential SLR of the East Antarctic Ice Sheet (Luhn, 2023)
A
52m
- it is beginning to melt
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
10
Q
When was the EAIS found to be gaining mass overall (Luhn, 2023)
A
2012
- Comes from satellite gravimetry estimates from King, 2012
11
Q
Where contains 4/5 of world ice (Luhn, 2023)
A
EAIS
12
Q
Why is EAIS more important to SLR than WAIS (Luhn, 2023)
A
- 52m SLR vs 3-4m SLR
13
Q
What has sea ice extent around AIS now dropped below (Luhn, 2023)
A
- 2 million sq km
14
Q
What tradiaonally prevented AIS from melting (Luhn, 2023)
A
- Circumpolar winds and ocean currents isolating it
15
Q
What was the Antarctic heat wave like in 2022
A
- 39 degrees higher than av temp in March 2022
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)
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
18
Q
What is the Arctic getting (Amos, 2022)
A
Wetter
- 10-15% since 1950
19
Q
Limitations of understanding snowfall and precipitation in the Arctic (Amos, 2022)
A
- Spareness of minirtoing stations
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
21
Q
Define cryospehre (IPCC, 2021)
A
- The components of the Earth system at and below the land and ocean surface that are frozen
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”
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%
24
Q
Define permafrost
A
- The components of the Earth system at and below the land and ocean surface that are frozen.”
25
Must know IPCC quote (IPCC, 2021)
"The cryospehre is undergoing rapid changes, with increased melting and loss of frozen water mass in most regions"
26
What is permafrost defined by
Temperature, not ice cover
27
What do AIS and GrIS contain
>99% of all land ice
>68% of freshwater
28
Impact of ice sheet melt globally (IPCC, 2021)
- Enough SWE to raise sea level by 65m
29
What causes imbalances in ice sheet volume
Imbalances between accumulation and ablation
30
Define mass balance
Difference beween accumulation and ablation
31
Major contributor to accumulation
Snowfall
32
GrIS area (Ringot et al., 2011)
1.7m km2
33
GrIS volume (Ringot et al., 2011)
3 m km3
34
SLE of GrIS (RIngot et al., 2011)
7.4m
35
Volume of AIS (Ringot et al., 2011)
30m km3
36
SLE of AIS (Ringot et al., 2011)
60m
37
Where do ice sheets mostly loose mass
Marine terminating glaciers or ice streams
38
Example of an ice tounge where a floating secion has passed the grounding line
- Peterman Glacier Ice Tougne in NW Greenland
39
Example of an ice shelf melted
Larcen C ice shelf, Antarctic Peninsular
A38A broke away in 2017 and completely melted by 2021
40
How are ice sheets measured (van Kampenhout et al., 2020)
1. Input output method
2. Satellite altimetry
3. Gravimetry
41
How does input-output method work (van Kampenhout et al., 2020)
- 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
42
What did Joughin et al., 2017 do
- Tracked the velicty of ice sheets using opitcal imagery, SAR images and InSAR
43
Accuracy of InSAR
- cm
44
Main limitation of using InSAR to measure velocity
- Good where there is little change but not good when there is lots of movement which will happen more due to climate change
45
Example of altimeter
CryoSat2
46
What is satellite altimerty (Moholdt, 2011)
- Using satellites to measure surface elevation by taking measuremnts of difference to calculate height change
47
How is feature tracking achieved
MODIS or LandSAT
48
How is gravimetry done
- GRACE Satellites 220km apart measturing the gravitational field directly
49
Limitations of gravimetry
- Limited spatial res of 50,000km2
- Montly temporal res
- Has to account for isostatic adjustment
50
GrIS trends from 1972-80
Mass gain of 47 Gt/yr
51
GrIS trends from 2010-18
Mass loss of 80 Gt/yr
52
How much SLR has GrIS caused since 1972
14mm
53
How much has GrIS mass loss increased in the last decade
6x
54
At what rate is GrIS thinning
9.84m/yr
55
How much ice loss did GrIS have in 2020
600 Gt
- 142% higher than equillibirum level
56
At what rate is GrIS loosing ice
261 Gt/yr (NASA, 2020)
57
How much SLR did GrIS contribute to in 20th century
25mm
58
Example of glacier in GrIS that gained mass up to 1990 before losing it
Helheim glacier
59
What has GrIS caused
1/3 of global sea level rise since 1993
60
Causes of GrIS causing SLR
- changes in atmospheric circulation
- 2019 had highest runoff since 1948
- Natural variations
- Albedo
- Enhanced melt
- Faster velocity
61
Antarctica rate of loss
150 Gt/yr (NASA, 2023)
62
What is biggest threat of AIS in future
WAIS melting
Especially vulnerbale is the Thwaites Glacier
63
Under SSP8.5 how much SLR will GrIS cause (Hofer et al., 2020)
Up to 0.18m
64
Under SSP8.5 how much SLR will AIS cause (Hofer et al., 2020)
Up to 0.34m
65
GrIS contribution to SLR in early 20th century (IPCC, 2001)
0.1mm/yr
66
GrIS contribution to SLR in late 20th centiry (IPCC, 2001)
0.23mm/yr
67
GrIS contribution to SLR in early 21st century (IPCC, 2019)
0.69mm/yr
68
GrIS contribution to SLR in 2023 (IPCC, 2019)
0.77mm/yr
69
GrIS contribution to SLR under SSP8.5 by 2050 (IPCC, 2019)
0.88mm/yr
70
GrIS mass sheet loss in late 20th century (IPCC, 2001)
83 Gt/yr
71
GrIS mass loss in early 21st century (IPCC, 2019)
248 Gt/yr
72
GrIS mass loss in 2023 (IPCC, 2019)
279 Gt/yr
73
GrIS mass loss by 2050 under SSP8.5 (IPCC, 2019)
- 317 Gt/ur
74
AIS mass loss in late 20th century (IPCC, 2001)
91 Gt/yr
75
AIS mass loss in early 21st century (IPCC, 2019)
- 182 Gt/yr
76
AIS mass loss in 2023 (IPCC, 2019)
151 Gt/yr
77
AIS mass loss by 2050 under SSP8.5 (IPCC, 2019)
- 183 Gt/yr
78
AIS SLR in early 20th century (IPCC, 2001)
0.2mm/yr
79
AIS SLR in late 20th century (IPCC, 2001)
- 0.27mm/yr
80
AIS SLR in early 21st centiry (IPCC, 2019)
- 0.50mm/yr
81
AIS SLR in 2023 (IPCC, 2019)
0.43mm/yr
82
AIS SLR by 2050 under SSP8.5 (IPCC, 2019)
0.51mm/yr
83
When was AIS losing more mass than GrIS
Late 20th century
91 Gt/yr vs 83 Gt/yr
84
Current disparity between GrIS and AIS
GrIs losing more
279 Gt/yr vs 151 Gt/yr
0.77mm/yr vs 0.42mm/yr
85
Late 20th century (IPCC)
GrIS - 83Gt/yr, 0.23mm/yr
AIS - 91Gt/yr, 0.27mm/yr
86
Early 21st centry (IPCC)
GrIS - 248Gt/yr, 0.69mm/yr
AIS - 182Gt/yr, 0.50mm/yr
87
2023 IPCC
GrIS - 279Gt/yr, 0.77mm/yr
AIS - 151Gt/yr, 0.42mm/yr
88
2050 IPCC SSP8.5
GrIS - 317Gt/yr, 0.88mm/yr
AIS - 183Gt/yr, 0.51mm/yr
89
Define sea ice
Ice on the sea surface that has originated from the freezing of seatwaer
90
Where is sea ice found
Polar regions, the Arctic ocean and the Southern Ocean
91
What % of Earth's surface does sea ice cover
7%
92
How is sea ice catergorised - 2 ways
According to its age
Whether it can drift
93
Ages of sea ice
New ice
Nilas
Young ice
First year ice
Perennial ice
94
What are polynas
A polynya is an area of open water surrounded by sea ice.
95
How is ice categorisedd by whether it can drift
Fast ice - fastened to the shoreline
Drift ice - free to move with wind and currents, ranging from small to giant
96
How can sea ice be calculated
Early data
Satellites
Reanalysis
Modelling
97
Early data for sea ice
- Written records
- Ice records
- Shipping routes
- Submarine sonar
- Whaling records
- Ship log books
- Proxies
98
Satellite data for sea ice
- 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
Reanalysis for sea ice
- PIOMass Assimilation System
- Assimilation of model and surface temperature data
- Ocean Renalaysis Interc
- Looks at SIA
100
Modelling sea ice
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
Sea ice change in Arctic
-13% per decade from Sept 1979-2018 (IPCC, 2021)
102
How much smaller is sea ice in Arcic in 2010-19 vs 1979-88
25% smaller
103
How much thinner is sea ice
72% thinner
104
When is sea ice min and max
Min in Sept
Max in March
105
What % of loss are anthropogenic forcings responsible for
1/2
106
What is less common
Multi-year sea ice
33% in 1985
1.2% in 2019
107
What is happening to Antarctic sea ice
Not much - little net change
Increase in Weddel and Ross Seas
Decrease in Amundson and Bellingshausen seas
108
Conflict between models on Antarctic sea ice
Renalsis shows increase in thickness whereas models show a decrease
109
What will the Arctic be by 2050
Sea ice free
For all SSPs
Reducing from 2mkm2 to under 1mk2 for SSP8.5
110
What is sea ice loss
Reversible
No tipping points
Negative feedbacks dominate over positive feedbacks
111
Arctic amplification
Artic projected to increase by 3-12 C by 2100
112
Summarise Karakoram Anomaly
Karakoram mountain range gaining glacier
113
