Lecture 3

Question 1

How are moulins created?

Answer 1

Surface meltwater absorbs 97%., the melted water creates

supraglacial lakes and rivers that enter moulins.

Through moulins, water is drained to the ice base and the meltwater accelerated the ice flow through basal sliding.

Question 2

What causes the mass loss on the Greenland Ice sheet?

Answer 2

60% of mass loss due to surface melting
40% of mass loss due to ice calving and sub-shelf melting
<1% of mass loss due to subglacial melting under grounded ice sectors

Question 3

Is the Greenland ice sheet losing or gaining mass?

Answer 3

Losing mass

Question 4

What are the major players in the surface mass balance of the Greenland Ice Sheet?

Answer 4

precipitation (mass gain)
surface energy balance (mass loss)
and ocean (mass loss)

Question 5

Why do we find ice cores 20 times older at the Antarctic ice sheet than the Greenland ice sheet?

Answer 5

The Greenland ice sheet is approximately 3 km thick, while the Antarctic is about 5 km thick. However, substantial basal melt is also happening at the Greenland Ice sheet, which has removed the oldest ice.

Question 6

What causes the North-Eastern Greenland Ice Stream?

Answer 6

Greenland’s passage over the Iceland mantle plume has created a strong geothermal anomaly
causing rapid ice flow in fast ice melt and a high concentration of subglacial hydrological
routes that spring from the anomalous area.