The cryosphere Flashcards
Define cryosphere
Any part of the Earth that is below 0 degrees C for any part of the year
What are the main contributors to sea level rise?
Mountain glaciers
What are three important things about the cryosphere?
Very reflective
Temperature differences
Amplify changes / variability
What helps to maintain water supplies?
Glaciers
Where can glacial ice be found?
At the poles and high latitudes
What are 6 forms of glacial ice?
Ice sheets Ice caps Ice streams Ice shelves Valley glaciers Outlet glaciers
How large are ice sheets?
Over 50,000km2
How do ice sheets respond to climate change?
They respond quickly
How big are ice caps?
They are less than 50,000km2
What do ice caps have?
Multiple outlet glaciers
What do outlet glaciers do?
They move ice from the centre to the outside
Give two examples of ice sheets
Greenland and Antarctica
Give an example of an ice cap
Novaya Zemlya
What is an ice tongue?
This is where part of a glacier sticks out
Where do tidewater glaciers terminate?
In the water
What are ice streams bordered by?
Ice
What are outlet glaciers bordered by?
Rock
What are ice shelves?
Extensions of glaciers across oceans
What are ice shelves not the same as?
Ice shelves are not the same as sea ice
Why aren’t ice shelves the same as sea ice?
Sea ice is made from sea water
What are valley/ mountain glaciers?
These are single glaciers
Where do valley/ mountain glaciers form?
They form at high elevations
Give a place where debris covered glaciers are present
Himalayas
What is the glacier mass balance?
This is how much is put in compared to how much is put out
What does glacier mass balance drive?
Glacier movement between input and output
Give an example of an outlet glacier with an ice tongue
Petermann Glacier
Give an example of a tidewater glacier
Helheim Glacier
Give an example of a place where there are ice streams
Siple coast
How does snow in glaciers change?
It goes from snow, to firn to ice
What is firn?
Crystalline or granular snow
What are icebergs?
These are chunks of ice that break off ice caps, ice shelves and glaciers
When do ice bergs and ice shelves raise sea level?
They only raise sea level when they first leave land and push into the water
Why do ice bergs break off?
Because of temperature rise
What is glacier input called?
Accumulation
What is glacier output called?
Ablation
What climates can glaciers be found in?
Maritime climates
Tropical areas
Continental climates
Give an example of a glacier from a maritime climate
Franz-Josef Glacier, NZ
Give an example of ice in a continental climate
Dry Valleys, Antarctica
What is the input and output like in maritime glaciers?
Lots in, lots out
Very responsive to change
What are dry valleys known as?
Continental glaciers
What is the input and output like in continental climates?
Not much in or out
Not very responsive to change
What happens to the mass balance if there is more accumulation than ablation?
The mass balance is positive
What happens to the mass balance if the accumulation is the same as the ablation?
Then the glacier is in balance
What happens to the mass balance if accumulation is less than ablation?
Then the mass balance is negative
What type of mass balance is good for glaciers?
Positive
What is the most common type of mass balance?
Negative
Where are 3 key places for ice loss?
Glacial Canada
Alaska
Himalayas
How much sea ice is there?
About 25 million km2
What is sea ice?
Frozen sea water
What are 4 reasons why sea ice is important?
Global ocean circulation
Wildlife and people
Shipping
Reflectivity
What are gaps in sea ice called?
Leads
Where is sea ice found?
At the poles
How can sea ice affect global ocean circulation?
It can change salinity
What is sea ice important for?
Albedo
What does an albedo of 0 mean?
It is a perfect absorber
What does an albedo of 1 mean?
It is a perfect reflector
What happens to the albedo if sea ice melts?
The albedo is lowered
What happens to the amount of sunlight absorbed if albedo is lowered?
A lowered albedo leads to an increase in absorbed sunlight
What type of feedback system does melting sea ice cause?
Positive feedback
What sort of seasonality does sea ice have?
Quite a strong seasonality
How much sea ice is there in the Arctic in March?
14-16 million km2
How much sea ice is there in the Antarctic in February?
3-4 million km2
How much sea ice is there in the Arctic in September?
7-9 million km2
How much sea ice is there in the Antarctic in September?
17-20 million km2
Are sea ice patterns similar in the Arctic and Antarctic?
No- they are different
How thick is Antarctic sea ice?
1m
How thick is Arctic sea ice?
2m
Why is Arctic sea ice thicker?
This is because it is trapped by the landmasses, causing ice to bump together and get thicker, making the ice last longer
In which place is sea ice more extensive in summer?
Arctic
In which place is sea ice less extensive in summer?
Antarctica
In which place is the sea ice asymmetric?
Arctic
Why is sea ice asymmetric in the Arctic?
There is more land which gets in the way and the North Atlantic current means that ice can’t form in some places
In which place is sea ice symmetrical?
Antarctica
Why is sea ice symmetrical in Antarctica?
It is in a circular shape because of the currents
Has sea ice in the Arctic increased or declined?
It has declined
By what percentage has sea ice declined in the Arctic?
4.1% decrease per decade
What was the trend for sea ice decline and increase in the past for the Arctic?
It used to increase then decrease yearly however the decreases are getting bigger and the increases aren’t able to fully compensate
Has sea ice increased or declined in Antarctica?
It has increased
By how much has sea ice been increasing in Antarctica?
It has had a small increase of 0.9% per decade
What are 5 reasons for the increase in Antarctic sea ice ?
Glaciers are melting and fresh water freezes faster
Change in wind direction
It is spatially highly variable, leading to regional patterns- some areas are gaining sea ice whereas others are losing it
Changes in precipitation
Change in satellites/ methods
Why is there very little snow on Arctic sea ice?
There is very little moisture
Why is snow present on Antarctic sea ice?
There is a lot of moisture from the water
What percentage of the Northern Hemisphere is covered by snow in January (winter)?
49%
Why is snow important? (2)
It reflects sunlight and radiation
Water resources
What is happening to the amount of snow?
It is declining
What month is seeing the largest decline in snow?
June
Is the amount of snow cover variable?
Yes- it is highly variable year on year
Define permafrost
Soil or rock that remains at or below 0 degrees C for at least two consecutive years
Where are the two main places that permafrost is found?
Polar permafrost
Alpine permafrost
What is the mean snow cover in January?
45.2 x 10^6 km2
What is the mean snow cover in August?
1.9 x 10^6 km2
Where is polar permafrost located?
High latitudes
Where is alpine permafrost located?
High altitudes
What are the 3 types of permafrost?
Continuous
Discontinuous
Sporadic
Give an example of a place with alpine permafrost
Tibetan Plateau
What percentage of the Northern Hemisphere is covered in permafrost?
25%
Explain continuous frost
Its continuous (not split) Formed in very cold areas
Explain discontinuous permafrost
Split by rivers or other areas of warmer land
Explain sporadic permafrost
Small areas/ bits and pieces
What happens to the type of permafrost as the Earth gets warmer?
It goes from continuous to discontinuous to sporadic and then disappears
What qualifies as continuous permafrost?
90-100%
-6 degrees C to -8 degrees C
What qualifies as discontinuous permafrost?
50-90%
-1 degrees C
What qualifies as sporadic permafrost?
Less than 50%
What is permafrost a store of?
Greenhouse gases
How much carbon is estimated to be in permafrost?
4 x the amount of carbon (possibly methane as well but check this) from anthropogenic
How does permafrost release greenhouse gases?
Through gas hydrates
Explain gas hydrates
Methane, CO2 and other gases are frozen into the permafrost and released through melting
What happens to permafrost when air temperatures increase?
Increased permafrost temperature and active layer thickening leads to permafrost thaw
What happens when permafrost starts to thaw?
Organic material begins to decompose which emits greenhouse gases causing the cycle to start again
What are key impacts from permafrost thaw?
Changes in ecosystems
Rock fall in mountainous areas leading to more mountain hazards
Infrastructure e.g roads and oil and gas pipelines- permafrost could cause the pipeline to crack
