Sea level change

Question 1

Eustatic change

Answer 1

A global change in sea level caused by a change in the volume of water in the sea or by a change in shape of the ocean basins.

Question 2

Causes of eustatic change

Answer 2

Climate -
increase in temp = ice sheets melt
hotter water = expansion
decrease in temp = more precipitation as snow, increasing the volume of water stored in glaciers and reducing the volume of the sea.

Tectonic movements -
the shape and volume of ocean basins can be altered.

Question 3

Isostatic change

Answer 3

A local change in sea level caused by vertical movements of land in relation to the sea.

Question 4

Causes of isostatic change

Answer 4

Ice sheets can cause uplift or depression. When the ice melts there is uplift as the weight of the glacier has gone.
Subsidence of land due to shrinkage after abstraction of groundwater.
Tectonic processes such as one plate being forced underneath another.

Question 5

Short term sea level change

Answer 5

Tides mean that sea level varies on a daily basis.

Onshore winds and low atmospheric pressure systems also cause the sea surface to rise temporarily.

Question 6

Long term sea level change

Answer 6

At the last glacial maximum, sea level was about 130m lower than present.
As the last glacial period ended (12,000 years ago), sea level rose rapidly and it reached its present level 4000 years ago.
It has been fluctuating ever since, but has been rising since 1930.

Question 7

Climate change

Answer 7

Between 1900 and 2016, the average global temperature rose by 1.08 degrees.
This means that sea level is also rising (at a rate of 2mm a year).
If human activity remains harmful, this figure is precited to increase to 8-16mm by 2100.

Question 8

Storms

Answer 8

Climate change means they will be more frequent and more intense due to changes in ocean circulation and wind patterns. This can cause damage to coastal ecosystems and settlements.
This will increase coastal erosion putting homes, ecosystems and businesses at risk.

Question 9

Kings Point, New York

Answer 9

An area affected by sea level rise due to flooding.

The area flooded around 160 times between 2005-2014.

Question 10

Maldives

Answer 10

A low-lying island at risk of submergence. Most of it will submerged if the sea level rises by just 0.5m.

Question 11

Bangladesh

Answer 11

A country affected by sea level rise due to changes in the coastline. If the sea level rises by 0.3m, 8000km2 of its land will be lost.

Question 12

Farmland and water sources

Answer 12

Salt water may contaminate fresh bodies of water near the coast, damaging ecosystems and making it unsuitable for lots of uses.
Salt water entering soils may damage crops and make land impossible to farm.

Question 13

Raised beaches

Answer 13

Formed when a fall in sea level leaves beaches above the high tide mark. Overtime beach sediment becomes vegetated and develops into soil.

Question 14

Wave-cut platforms

Answer 14

They can become exposed as sea level falls, leaving them raised above their former level.

Question 15

Relict cliffs

Answer 15

Cliffs above raised beaches that are no longer eroded by the sea. They are gradually weathered over time.

Question 16

Rias

Answer 16

Formed when river valleys are partially submerged. They have a gentle long and cross-profile, becoming narrower and shallower the further inland the reach.

Question 17

Fjords

Answer 17

Former glacial valleys drowned by rising sea levels. They are relatively straight and narrow with very steep sides.
They are very deep further inland, e.g. Sognefjorden in Norway is over 1000m deep in places.

Question 18

Dalmatian coastlines

Answer 18

Formed when valleys that are parallel to the coast are flooded, leaving islands parallel to the coast.
e.g. Dalmatian Coast, Croatia.