Sea Level Rise And The Earths Ice Sheets

Question 1

Cyrosphere (frozen things) contributions to SLR

Answer 1

Snow on land (not big)
Sea ice (doesn’t effect SLR)
Glacier
Seasonally frozen land and permafrost (not issue to SLR)
Ice shelves (areas of ice that have already come afloat, lost contact with earth so don’t add to SLR
Ice caps (small ice fields, based on land, with some glaciers linking to sea

Question 2

Climates for sustaining glaciers

Answer 2

Made out of snow falling and then not melting

Higher temps & higher precipitation - can deal with warmer temps if there’s enough snow
Or Lower temp & low precipitation

Question 3

Glaciers lost

Answer 3

Wet climates- Olympic national park - 30% glacier area lost from 1970s to 2009, 15% volume loss during 1987-2009

Cold, dry climates- 150 glaciers in Glacier National Park in 1880, now 25
Modelling suggests some of the parks glaciers will disappear by 2030

Warming can initially contribute to mass of glaciers as warmer air can hold more water, but not enough to make up for loss

Question 4

How is ice lost from ice sheets?

Answer 4

Ice lost from melt
Surface melt mainly in Greenland (not Antarctica)
Ice lost from calving (spilt)

Question 5

Greenland ice sheet

Answer 5

Fastest moving glacier, 16km a year
3km of ice sheet in middle

Different parts move at different velocity, interior melts vey rarely, outside edges higher velocity, in contact with ocean, conveyer belts

Floating ice tongue- glacier is flowing out from ice sheet, looses contact with ground, floating ice, surface water (drains to base of ice sheet), ocean water creates melt below, can produce calving

Question 6

How does the ocean affect the glaciers?

Answer 6

North Atlantic current bring warm salty water, 200m deep

Colder fresh layer in upper layers of the ocean

Glaciers deep in the ocean

Warm water will access glaciers

Leads to thinning- surface melt

Widespread retreat, widespread speed up (result of destabilisation)

Question 7

Story in Greenland

Answer 7

Thinning, retreat, speed up

If a glacier is resting below sea level, as it retreats it’s still in contact with warming water, making it less stable

Question 8

Antarctic ice sheet

Answer 8

1-2 km movement (much slower than Greenland)
Ice shelves around the ice sheet (area where all of the grounded ice is flowing out, loosing contact with ground below and becomes an ice shelf) (loss of ice shelf doesn’t contribute to SLR)

Ice shelf impact- relatively warmer ocean temperatures thins ice shelves, buffer for grounded ice, hold back glaciers behind them
Loss of ice shelf leads to surface melt, which increases glacier velocity, more ice move to ocean more quickly

Question 9

West Antarctica

Answer 9

We expect to lose ice from west first

Due to Marine ice sheet instability

Ice in contact with ocean which makes it less stable