Permafrost and periglacial landscapes

Question 1

Define periglacial environment

Answer 1

Cold but non-glacial, regardless of proximity to glaciers

Question 2

Define permafrost

Answer 2

Soil or rock that remains at or below zero degrees C for at least two consecutive years

Question 3

What are the 3 layers of permafrost?

Answer 3

Active layer
Permafrost
Talik

Question 4

What does the active layer of permafrost do?

Answer 4

Freezes and melts with the seasons

Question 5

What is an issue with humans and the active layer of permafrost?

Answer 5

Can’t build infrastructure

Question 6

What is the talik?

Answer 6

Thawed area below the permafrost

Question 7

Why does talik occur?

Answer 7

Because of geothermal heat

Question 8

How deep can permafrost be?

Answer 8

Over 1km deep in places

Question 9

What 4 things can control permafrost characteristics?

Answer 9

Geothermal heat
Land cover e.g. trees/ buildings
Mean annual temperature (colder = thicker permafrost)
Ground conductivity

Question 10

Where can permafrost be found?

Answer 10

Polar permafrost

Alpine permafrost

Question 11

What percentage of the Earth does permafrost cover?

Answer 11

20%

Question 12

Why is permafrost found in polar environments?

Answer 12

Due to high latitude

Question 13

Why is permafrost found in alpine environments?

Answer 13

Due to high altitude

Question 14

What are the 3 types of permafrost?

Answer 14

Continuous
Discontinuous
Sporadic

Question 15

What are the continuous permafrost temperatures?

Answer 15

-6 to -8

Question 16

What is the discontinuous permafrost temperature?

Answer 16

-1

Question 17

How much permafrost should there be in order to be classed as continuous?

Answer 17

90-100%

Question 18

How much permafrost should there be in order for it to be classed as discontinuous?

Answer 18

50-90%

Question 19

How much permafrost should there be in order to class it as sporadic?

Answer 19

Less than 50%

Question 20

What is ground temperature related to?

Answer 20

Air temperature

Question 21

What is the general trend for polar permafrost?

Answer 21

Ground temp is linked to permafrost. Colder towards the poles. For areas where this is not the case this could be due to vegetation or geothermal heatflux

Question 22

What is the general trend for alpine permafrost?

Answer 22

Lower elevations have less permafrost in the Northern Hemisphere (less sunlight)

Question 23

What is another unexpected location for permafrost?

Answer 23

Under the ocean

Question 24

What is GPR?

Answer 24

Ground Penetrating Radar

Question 25

What does GPR look at?

Answer 25

At the structure of the subsurface. It reflects off of things on the subsurface e.g. water or layers of rock or soil

Question 26

What does GPR allow you to see?

Answer 26

How deep the permafrost is and where the gaps are

Question 27

What are 4 engineering challenges?

Answer 27

Frost heave Thawing and subsidence Saturation Freezing of buried pipes

Question 28

How does frost heave work?

Answer 28

Water freezes and expands, this causes the building to be lifted up. In the summer, when it melts the building will move down. Here the permafrost will be uneven.

Question 29

How does thawing and subsidence work?

Answer 29

Can cause a big gap, causing the buildings to fall downwards. Likely to be uneven

Question 30

How does saturation work?

Answer 30

Melting in summer leads to water, however this is trapped and cannot move. Essentially like building on a lake

Question 31

What is the issue of freezing of buried pipes?

Answer 31

Liquid freezes and expands, could cause the pipe to burst

Question 32

What is the passive strategy of permafrost?

Answer 32

Minimise disturbance

Question 33

Give an example of a passive strategy?

Answer 33

Drill supports for houses into the permafrost

Question 34

Where does the passive strategy work?

Answer 34

In areas with thick, continuous permafrost

Question 35

What is the active permafrost strategy?

Answer 35

Destroy permafrost- get rid to build on solid ground

Question 36

Where are methods of active strategy effective?

Answer 36

In sporadic areas

Question 37

Why are roads ventilated?

Answer 37

To make sure they don't get too hot

Question 38

Why is insulation installed in permafrost?

Answer 38

To stop it from getting too hot

Question 39

How long is the Trans-Alaskan pipeline?

Answer 39

1285km long

Question 40

What does the Trans-Alaskan pipeline transport?

Answer 40

Oil

Question 41

Why can't the Trans-Alaskan pipeline be put underground?

Answer 41

Oil flows best at 70 C which would melt permafrost so they have to put it on stilts

Question 42

How long is the Tibet railway line?

Answer 42

1100km long

Question 43

Why is the Tibet railway is important?

Answer 43

It is one of the only ways to get across Tibet

Question 44

How is the Tibet railway adapted to permafrost?

Answer 44

It is on stilts and is insulated from the permafrost

Question 45

What is freeze thaw?

Answer 45

Ground freezes and expands, then refreezes and contracts, this causes rocks to crack

Question 46

What is frost creep?

Answer 46

When it freezes it moves upwards at a right angle in the active layer but when it melts it sinks back down due to gravity

Question 47

What is gelifluction?

Answer 47

Active layer melts in summer and becomes fluid, as the bit below is frozen, it has to flow downhill

Question 48

What are braided rivers?

Answer 48

Lots of different channels that transport material. Very seasonal in terms of meltwater inputs (high in summer, low in winter)

Question 49

Where do ice wedge polygons form?

Answer 49

In areas of continuous permafrost

Question 50

What temperature is required for ice wedge polygons to form?

Answer 50

-15 C

Question 51

How are ice wedge polygons formed?

Answer 51

Water enters a crack in the summer, freezes in the winter and pushes it a part. Continuous process creates a big crack in the landscape

Question 52

What are the 2 types of pingo?

Answer 52

Closed system pingos (hydrostatic) | Open system pingos (hydraulic)

Question 53

How are closed system pingos formed?

Answer 53

A lake has frozen sediment underneath, when the lake drains the top starts to freeze and expand, pushing up the ground to form lumps

Question 54

How are open system pingos formed?

Answer 54

Water drains through the ground and hits an area through which it can't drain because of the permafrost. Here it freezes and pushes the land up

Question 55

What is a thermokarst?

Answer 55

An uneven landscape with hollows filled in of water with patches of thaw and frozen areas

Question 56

What could thermokarsts be important for?

Answer 56

Greenhouse gases

Question 57

Why are the impacts of warming bigger in the Arctic?

Answer 57

Due to feedbacks with sea ice and albedo

Question 58

What is meant to happen to the air temperature and what other temperature will this affect?

Answer 58

There is expected to be major air temperature warming and therefore major ground temperature warming

Question 59

What is likely to happen to the permafrost this century?

Answer 59

It is likely that a lot of permafrost will be lost (worst case scenario)

Question 60

What will happen if permafrost is lost in terms of greenhouse gasses?

Answer 60

There will be more CO2 and CH4 in the atmosphere

Question 61

What are large parts of the Russian Arctic affected by?

Answer 61

Permafrost melt

Question 62

What is an impact of the release of extra greenhouse gases?

Answer 62

Economic impacts

Question 63

How could ecosystems change as a result of permafrost loss?

Answer 63

Drunken trees Fires Insect infestation

Question 64

What is the warming like across the Alps?

Answer 64

Consistent and substantial

Question 65

What is an issue with warming in the Alps?

Answer 65

Mountain hazards and landscape stability

Question 66

What is the issue with landslides?

Answer 66

They are difficult to predict

Question 67

What is released as a result of permafrost thaw?

Answer 67

Hydrates

Question 68

Why are hydrates released?

Answer 68

Through gradual thaw of the permafrost- soil under lake can be thawed very quickly

Question 69

What is the issue with climate change?

Answer 69

Can have rapid and unpredictable events

Question 70

What happens to the active layer as a result of increased air temperatures?

Answer 70

It thickens