Glacial Dynammics & Systems

Question 1

Glaciers as a system

Answer 1

-glaciers are open systems with inputs and outputs to external systems, including fluvial and atmospheric systems
-there are flows of energy, ice, water and sediments between stores

Question 2

Mass balance

Answer 2

-the gains and losses of ice within a glacier
-more accumulation gives a positive mass balance
-negative mass is where there is less accumulation than ablation
-dynamic equilibrium is where they are balanced over a year

Question 3

Case study- Greenland ice sheet location

Answer 3

-found between the arctic and northern Atlantic oceans, northeast of Canada and northwest of Iceland
-largest ice mass in the northern hemisphere
-coveres roughly 80% of greenlands landmass, an area of 1.7 million km2

Question 4

Greenland ice sheet- historical data

Answer 4

-was part of a series of ice sheets covering large parts of northern hemisphere during the last ice age
-during the glacial maximum it held an extra 4.1m of ice and is the only one remaining in the current interglacial period

Question 5

Greenland ice sheet- current data

Answer 5

-mass loss of ice over recent decades
-mainly due to increased air and ocean temps
-Greenlands melt season has dropped well below the 1981-2020 average
-as a result, global mean sea levels have risen by approx 0.7mm which is greater than the Antarctic ice sheet contribution

Question 6

Greenland ice sheet- future

Answer 6

-continued global warming will increase the rate of ice sheet melting as a positive feedback mechanism
-exposed ground reduces the albedo effect on the surface, increasing ground warming therefore snow melt
-increased melting leads to the release of stored carbon and methane into the atmosphere
-large amounts of freshwater could affect the thermohaline circulation and cut off equatorial warm waters arriving with the Gulf Stream along the coast of the UK

Question 7

Inputs

Answer 7

-accumulation from direct and indirect snowfall
-avalanches from one area onto the ice mass
-wind blown debris from another area onto an ice mass
-any accumulation is transferred down hill by gravity

Question 8

Outputs

Answer 8

-melting at the margins of the ice mass
-evaporation
-sublimation
-calving from the front margin where it meets the sea
-avalanches

Question 9

Accumulation zone

Answer 9

-found in the upper part of the glacier
-inputs are usually more than outputs
-net gain of ice during the year
-glacier front advances

Question 10

Ablation zone

Answer 10

-found in lower part of the glacier front
-output exceeds inputs
-net loss of ice during the year
-glacier front retreats

Question 11

Positive feedback back loop

Answer 11

-e.g sediment on the glacier absorbs isolation and begins heating
-leads to melting of ice
-exposing more sediment and increasing the rate of isolation absorption