Ice sheets, ice caps and extra-terrestrial ice Flashcards
What is the biggest contributor to sea level rise?
Glaciers
How much ice covers Greenland?
2.8 million km2
How thick is the Greenland ice?
Up to 3km thick
Where has the snow accumulated in Greenland?
In the centre
Where is ice being lost in Greenland?
At the margins
Why could Greenland and Antarctica be exploited?
For their mineral resources
Why hasn’t Antarctica been exploited for minerals?
It is protected by the Antarctic Treaty
How long until the Antarctic Treaty expires?
30 years
What is a problem that Greenland faces?
Trade routes are opening up through the country
What do outlet glaciers do?
They move ice from the centre to the oceans
What can be used to find the fast moving channels from outlet glaciers?
Remote sense data
What do channels transmit?
Climate change back inland
At what rate is Greenland losing ice?
At an increasing rate
Give an example of an outlet glacier with an ice tongue
Petermann glacier
Give an example of a tidewater glacier
Helheim glacier
By what two mechanisms is ice being lost in Greenland
Surface mass balance
Accelerated discharge
By what percentage does surface mass balance cause ice loss?
60%
By what percentage does accelerated discharge account for ice mass?
40%
What is surface mass balance?
Snow in, ice out
What has been seen in Greenland in recent years?
Accumulation has slightly increased in the centre however, the ablation on the margins outweighs this effect
In what year was the first year on record that there was melt across the entirety of the ice sheet?
2012
What is accelerated discharge from?
Outlet glaciers
What is accelerated discharge?
This is where more ice is lost through discharge
Which area of Greenland experiences more ice loss from accelerated discharge?
The North West
What is a good example of accelerated discharge?
Jakobshavn Isbrae in W greenland
For what percentage of overall discharge does Jakobshavn Isbrae account for?
6%
Between the 1950s and 1998 what did the Jakobshavn Isbrae do?
It stayed the same
Why was there a change in Jakobshavn Isbrae?
Warmer ocean waters reached the glacier
What happened to Jakobshavn Isbrae after the change?
Rapid retreat at the front of the glacierand velocity increase
What is the immediate response when outlet glaciers change?
Ice speed inland speeds up after ice berg is lost, causing the glacier to thin
What sort of time scale is dynamic thinning?
Long term
Why is dynamic thinning long term?
It takes a while for the ice to adjust
How is ice loss variable?
It is spatially variable
Give a brief explanation of areas of Greenland that have retreated
Early 2000s SE retreated, then stopped and the N started to retreat.
From 2010 onwards SE was variable but N continued to retreat
What 3 things have caused changes in Greenland?
Atmospheric warming
Sea ice
Oceanic warming
What can air temperatures cause?
Hydrofracture
What is hydrofracture?
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.
What happens if hydrofracture occurs at the terminus?
An iceberg could break off
What does sea ice do?
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
Which type of warming is more efficient at melting ice: oceanic or atmospheric?
Oceanic warming is more efficient at ice melt
What does ocean warming cause?
Submarine melting
What is submarine melting?
Where the water in contact with the ice causes it to melt
What is another way in which oceanic warming can cause ice to melt?
Melting can occur along the face of the glacier, it cuts into the glacier causing ice to fall off of it
What was originally thought to be the main reason for ice retreat?
Atmospheric warming
What was Zwally’s idea?
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
What has more research shown about hydrological system that disproves Zwally?
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
Which current has led the oceans around Greenland to warm?
The North Atlantic current
How has the North Atlantic current led to warming and loss of sea ice?
The temperature of the current has changed as well as its proximity towards the glaciers
Explain the mass balance of Greenland
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
What type of ice loss has longer term effects?
Glacier acceleration
What can cause outlet glacier retreat?
Submarine melting due to ocean warming
Reduction in sea ice
Thinning due to increased melting
Hydrofracture of crevasses
What are the two Antarctic ice sheets?
West Antarctic Ice Sheet
East Antarctic Ice Sheet
Which Antarctic ice sheet is bigger?
The East Antarctic Ice Sheet
What is the potential sea level rise for East Antarctica?
53 m
What is the potential sea level rise for West Antarctica?
3.3m
What separates the two Antarctic ice sheets?
The Transantarctic Mountains
Which Antarctic ice sheet is more stable?
The East Antarctic Ice Sheet
Why is the East Antarctic Ice Sheet more stable?
Due to its bed- the topography is above sea level
Why is the West Antarctic Ice Sheet more vulnerable?
Because it is a marine based ice sheet
What is meant by marine based ice sheet?
Its bedrock topography is below sea level
Why are marine based ice sheets vulnerable?
A series of feed backs can be set off, causing rapid ice loss
Is Antarctica losing or gaining ice?
It is losing ice
How is Antarctica losing ice?
Through surface mass balance and accelerated discharge
What are ice streams?
Fast flowing corridors that are not constrained by the bedrock topography
How much ice was lost at the Larsen B ice shelf on the Antarctic Peninsula in 2002?
3250 km2
Prior to this it had been in place for about 12,000 years
What are the causes of ice loss in the Antarctic Peninsula?
Unsure- could be ocean warming
What has been seen in recent years at the Antarctic Peninsula?
Collapse of its ice shelves
What are ice shelves?
Areas of floating ice that float out over the ocean
Why doesn’t losing ice shelves contribute to sea level?
They are already floating
What happens when ice shelves are removed?
The glaciers in land start to move a lot quicker because the ice shelf is not there to hold it in plaece
What is the limit of viability for ice shelve to survive?
Below -9 degrees C
What might happen to Larsen C ice sheet and why?
It is on the temperature limit of viability so it might go
Name two glaciers in the Amundsen Sea, Antarctica
Pine Island
Thwaites
What is the issue with Pine Island and Thwaites? (4)
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
What might’ve caused the issues seen by Pine Island and Thwaites?
Ocean warming
What is an issue with the bed of Pine Island and Thwaites?
Their bed slopes downwards inland and goes below sea level, causing marine ice sheet instability.
What happens as a result of marine ice sheet instability?
A series of feed backs. The glacier will retreat into areas of deeper bedrock and will not stop until it reaches a slope upland
What would happen to sea level rise if the Pine Island and Thwaites glaciers experienced marine ice sheet instability and collapsed?
Sea levels would rise by 1.5m
What is the Siple Coast also known as?
The Ross Sea sector
What is happening to the mass balance at the Siple Coast?
It has a positive mass balance and is not discharging much ice
Why does the Siple Coast have a positive mass balance?
The glaciers switch on and off all of the time
Why do the glaciers switch on and off at the Siple Coast?
To do with the type of sediment and whether it is frozen or thawed
What indications show that East Antarctica might be less stable than thought?
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
What is the Southern Annular Mode?
This is an atmospheric phenomenon around Antarctica
What is the temperature limit for ice shelves?
-9 degrees C
By how much will the Arctic contribute to sea level by 2100?
19-25cm by 2100
For what percentage of sea level rise could Arctic ice caps and glaciers contribute to?
35%
What happened to the Arctic between 2011-2015?
It was warmer than anytime since 1900
Which area of the Arctic is losing ice fastest?
Canadian Arctic followed by Alaska
What do Arctic ice caps have?
Surge type glaciers
What do surge type glaciers do?
Neither move slow or fast
They oscillate through two phases
What makes glaciers slow (look at mass balance)?
Small amount of mass coming in and out
What makes glaciers fast (look at mass balance)?
Large amount of mass coming in and out
What are the two phases of surge type glaciers?
Surge phase
Quiescent phase
What is the surge phase? (surge type glaciers)
Fast
What is the quiescent phase? (surge type glaciers)
Slow
How long does the surge phase last? (surge type glaciers)
1-10 years
How long does the quiescent phase last? (surge type glaciers)
10-100 years
What are surge-type glaciers independent of?
They cycle independent of climate changes
What happens to the thickness of the glacier when it is in its quiescent phase?
It builds up and gets thicker
What happens to the thickness of the glacier when it is in its in its surge phase?
It is thin as it chucks out all of the snow downhill
What triggers the surge phase? (3) (surge type glaciers)
Changes in thermal properties
Changes in basal hydrology
Changes in sediment at the bed
What is the cryosphere on Mars similar to?
That of Earth
Where is ice located on Mars?
It has polar ice caps at the poles
How extensive is the ice at the North Pole of Mars?
1000km diameter, 2km thick
How extensive is the ice at the South Pole of Mars?
350km diameter, 3km thick
What are the two forms of ice on Mars?
Water
CO2 ice
Why is there CO2 ice on Mars?
It is so cold on Mars that CO2 can be frozen
What does the CO2 ice do during the winter?
It creates a veneer of CO2 that expands over winter
Why is it important for us to locate ice on Mars and its properties? (2)
To determine climate history of Mars
For information about water
Where could there be life on Mars?
Under the ice
What are GLFs ?
Glacier like forms
Where can GLFs be found?
Mars mid-latitudes (30-60 degrees)
What type of ice do GLFs have?
Water
What do GLFs do?
They flow
What features do GLFs have?
Crevasses
Moraines
How many GLFs are there on Mars?
1300
What do GLFs tell us about Mars?
Climate history and where water and life might be found
