Glaciation Pack B

Question 1

What is a cirque/corrie glacier?

Answer 1

A small glacier that fills a hollow on a mountain side
- Constrained
- Carves out a corrie/cirque
- 0.5 to 0.8 km in size

Question 2

What is a valley glacier?

Answer 2

A glacier confined between valley sides/walls
- Constrained
- Terminates in a narrow tongue
- Formed from ice caps/sheets or cirques
- Might terminate in the sea as a tidewater glacier
- 3 to 1500 km in size

E.g. Aletsch glacier (Switzerland), Athabasca (Canada)

Question 3

What is a piedmont glacier?

Answer 3

A valley glacier that extends beyond the end of a mountain valley into a flatter area
- Constrained
- Spreads out as a fan
- 3 to 1000 km in size

E.g. Malaspina (Alaska)

Question 4

What is a highland ice field?

Answer 4

Where ice covers an upland area but it is not thick enough to bury topography
- Unconstrained
- Many don’t extend beyond the highland source
- Nun attacks are protruding bits of topography
- 10 to 10000km in size

E.g. Patagonia (Chile), Columbia (Canada)

Question 5

What is an ice sheet?

Answer 5

A gently sloping dome of ice that is several km thick in the centre
- Unconstrained
- Submerges topography completely
- 100000 to 10 million km in size

E.g. Greenland, Antarctica

Question 6

What is an ice cap?

Answer 6

A smaller version of an ice sheet that covers an upland area
- Unconstrained
- 3 to 10000km in size

E.g. Vatnajokull (Iceland)

Question 7

What is an ice shelf?

Answer 7

A large area of floating glacier ice extending from the coast
- Unconstrained
- Happens when several glaciers have reached the sea and coalesced
- 10 to 100000km in size

E.g. Ronne and Ross Ice Shelf (Antarctica)

Question 8

What is feedback?

Answer 8

Feedback effects are those that can amplify or diminish changes

Question 9

What is the difference between positive and negative feedback?

Answer 9

Positive feedback is amplifies or magnifies the change or output, moving the system away from equilibrium
Negative feedback is when the output is decreased, returning the system back to equilibrium

Question 10

What feedback loops occur associated with ice, temperature and climate change?

Answer 10

Positive feedback:
Increasing temperatures -> permafrost melting -> methane released
Increasing temperatures -> ice melting -> more dark surfaces -> increased absorption of solar radiaiton

Negative feedback:
Increased temperatures -> increased evaporation -> more clouds -> less sunlight entering -> decreased temps
Increased temperatures -> more photosynthesis -> less CO2 -> decreased temps

Question 11

How could ice dynamics affect the ocean conveyor belt or thermohaline circulation?

Answer 11

• Melting of the Greenland ice sheet will mean less warm water from the Gulf Stream
• Could lead to global cooling

Question 12

What leads to climatic changes of mass of ice in the short term?

Answer 12

Seasons:
- Low density of rays in winter making it cooler
- Due to the tilt of the Earth
- More accumulation in glaciers
- There is a positive mass balance in winter and a negative mass balance in summer

Question 13

What led to climatic changes to mass of ice in historical time frames?

Answer 13

Sunspots:
- Amount of energy emitted from the sun depends on how many sunspots it has at any given time
- Happens on an 11 year cycle
- Fewer sunspots means less energy emitted and may potentially cool Earth
- Only alters solar radiation by 0.1%

Volcanic eruptions:
- Violent volcanic activity (>VEI 4) leads to a decrease in global temperatures
- Ash and SO2 is released which is then distributed around the world by high altitude winds
- Ash blocks heat entering and SO2 reflects sunlight

E.g. Pintubo in 1991 cooled global temperatures by 0.5 degrees for a year

Question 14

What is the Little Ice Age?

Answer 14

A period of cooling where it was 0.6 degrees cooler
- 1300 to 1870 AD
- Regional in Europe and North America
- Due to a decrease in solar radiation, increase in volcanic activity and changes in ocean conveyor belt

Question 15

What is the Maunder Minimum?

Answer 15

A period of lower than average temperatures
- 1645 to 1715 AD
- Part of the Little Ice Age
- Only 50 sunspots compared to the expected 50,000

Question 16

What is the Medieval Warm Period?

Answer 16

A period of relatively warmer climate in the North Atlantic region
- 950 to 1255 AD
- Warmest period of the last 2000 years (until anthropogenic climate change)
- Due to changes in solar output and a decrease in volcanic eruptions

Question 17

What led to changes in mass balance over geological time frames?

Answer 17

Axial precession:
- 21,000 year cycle
- The Earth wobbles on its axis which changes the point in the year at which each pole is closest to the sun
- Affects seasons
- When the North Pole faces further away from the sun during our summer, there will be milder seasons and more ice build up

Axial tilt:
- 41,000 year cycle
- Tilt of Earth’s axis changes from 22 to 24 degrees
- Changes the intensity of sunshine at poles and changes seasons from milder to more extreme
- Greater tilt means a greater difference between summer and winter

Eccentricity:
- 100,000 year cycle
- Earth’s orbit changes from a circle to an ellipse
- Changes how close Earth is to the sun
- Low eccentricity (circle) means seasons are mild so ice builds up gradually

Question 18

How does the Milankovitch cycle led to climatic changes to mass of ice?

Answer 18

• A combination of all three lead to more or less ice but it only has a small impact itself
• It triggers feedback mechanisms which cause much larger changes