1. Changing Sea Levels
Beren, TOMO, Maddie, Amy-Jane, Emily and Lucia: March Updated: 18/03/15
G3.6

2. Introduction What is sea level change?
Sea level change is the height of the sea with reference to the land.
Isostatic sea level change is caused by vertical movements of the land relative to the sea. Any downward movement of the land causes sea level to rise locally while the rise in land causes sea level to fall. The effects are always local.
Eustatic sea level change is caused by a change in the volume of water in the sea or by a change in the shape of ocean basins. The effects are always global.

3. EUSTATIC CHANGE
Eustatic change is the global rise or fall of sea levels. This change is a GLOBAL change
A factor that can affect this is global warming. This happens because the increased heat changes the amount of ice stored on land as water, thus changing the sea levels. A rise in temperature will cause the ice caps to melt, and sea levels will rise, and vice versa.
The second factor that can affect this is the Steric effect. This is where the density of the water increases or decreases as the temperature rises or falls. If the temperature rises the water expands and if it falls the water contracts. It is estimated that sea levels can rise up to 0.4mm per year.

4. ISOSTATIC
Isostatic change is the adjustment of land levels. This change is LOCAL.
3 main physical factors affect this:
ice
uplift
seismic activity

5. Ice is the first way that can adjust the land
Ice is the first way that can adjust the land. This can happen when the land is covered by ice in one place. For example in the last ice-age, North Western Britain was covered in 1.5 km of ice. This immense pressure causes this area land to subside, whilst any other land (South Britain) will rise, like a see-saw. When the glacier ice melts, the weight is taken off the land, and so the land will begin to rise again, whilst the other area will sink. This happens very slowly, and is known as glacial (isostatic) rebound.
Uplift: Underlying tectonic forces, including uplift through folding and faulting can result in isostatic uplift (rise in land level) The land may rise as a result of tectonic plates pushing each other or removal of weight.
Seismic activity: earthquakes can cause both uplift and depression of land as a result of movement along fault planes.
Isostatic change can also happen due to human interference. The extraction of resources from low lying coastal areas may lead to compaction of land followed by subsidence (sinking).

6. ISOSTATIC ICE Isostatic local
Isostatic sea level change can be attributed to the wait of ice. And is a local change because the ice only covers a local area.

7. Eustatic
YOU STATIC change – caused by you as you cause global warming which cause ice cap melt which adds water to the see.

8. Landforms associated with rising sea levels. SUBMERGENT FEATURES
Dalmatian coastline:
In areas where valleys lie parallel to the coast an increase in sea level can form a DALMATIAN COASTLINE. Valleys are flooded leaving islands parallel to the coastline. This can be seen along the Dalmatian coast in Croatia.
Fjords-They’re drowned glacial valleys rather then drowned river valleys. They're relatively straight and narrow with very steep sides. They have a shallow mouth caused by a raised bit of ground (called the threshold) formed by the deposition of material by the glacier. They're very deep further inland e.g Sognefjorden in Norway is over 1000m deep in places.
Rias- are formed when river valleys are partially submerged. They’re wide and deep near the mouth becoming narrower and shallower the further inland they reach. An example of this would be the dart estuary in Devon.
Fjords Link

9. Dalmatian Coast Croatia
Dart Estuary
Sognefjorden

10. Uses of features created by sea Level change
SUBMERGENT Features
FJORDS
Uses of Fjords:
1. Tourism – Cruise ships
2. HEP – Dams
3. Agriculture
4. Settlements
A Fjord is a drowned river valley due to rising sea level.

11. USES of Fjords Tourism: Cruises - Deep Water SOCIAL : Leisure
Agriculture:
Subsistence farming
Transhumance
Summer and winter pastures.
Settlements
Off grid
Isolated and rural
Housing
Animals
Environmental/ Economic
Cold /Harsh
Tourism
HEP
Area’s of outstanding natural beauty

12. Uses of features created by sea Level change
SUBMERGENT Features
RIAS
Ports/ industrial
Tourism
Agriculture
Settlements
Flooded river mouth and lower course

13. Emergent Landforms Due to FALL IN SEA LEVEL
Appear towards end of Ice age
Isostatic rebound takes place faster than a Eustatic rise in sea level
Emergent Features-wave-cut platforms, coastal plains and raised beaches.
Raised beaches are wave-cut platforms & beaches that are above the current sea level.
Over time beach sediment becomes vegetated and develops into soil.You can normally find some old cliffs (relict cliffs) too behind these raised beaches with wave-cut notches, arches, stacks etc. along them.
These emergent features no longer experience coastal erosion and slowly get covered by vegetation but they are still weathered, often being weathered biologically, chemically and via freeze-thaw weathering.
Common along the West coast of the UK this is because the area experienced the greatest weight of ice during the last Ice Age (about 10,000 years ago).

14. Portland-Raised Beach
Portland-South West Coast of the UK
Warm interglacial phase of the Pleistocene ice ages approx. 200,000 years ago
Pebbles represent a beach when the sea was approx. 15m above the present level.
The loam (sandy slit) above the raised beach was originally wind deposited, and is capped by a "head" formed during the last major glacial episode to have affected Britain – The Devensian. The head contains much limestone rubble broken up under severe arctic conditions.

15. Coastal Plains
A coastal plain is a flat, low-lying piece of land next to the ocean. Coastal plains are separated from the rest of the interior by nearby landforms, such as mountains.
Coastal plains start as a continental shelf, a flat piece of land located below sea level. When the ocean level falls, the land is exposed, creating a coastal plain.
The Gulf Coastal plain of North America extends northwards from the Gulf of Mexico to the Ohio river. During the crustaceous period the central area of the United States was covered by a shallow sea which disappeared as the land rose.

16. IMPACTS of rising sea levels
Higher mean sea levels could have an impact on underground water resources.
Rising sea levels could also affect coastal habits, particularly wetlands and salt marshes.
A number of areas around the British coastline are potentially at risk from rising sea level. These include major Cities, such as London, hull and Middlesbrough, and high grade agricultural land. Major road and rail links near the coast are also at risk, and several power stations are situated on low lying ground.
Much of the east coast of Britain is at serious risk of flooding due to inadequate sea defences and the willingness of planning authorities to allow development along low lying area.
The increased concentration of housing and other developments of land at risk of flooding is likely to raise insurance costs.
Farmers are paid up to £600 for each hectare of land that reverts to salt marsh.
The zone where sea water mixes with fresh watering rivers is dynamic and a rise in sea level can cause it to move upstream. A similar affect can occur between fresh water contained in rocks under the land and salt water in sea sediment, ;evading too intrusion of salt water beneath the land. This would adversely affect some points along the low reaches of river where water is abstracted for domestic and irrigation purposes these abstraction pints would have to be moved upstream or become intermittent to avoid abstracting saline water.
The extent to which ecosystems are likely to be affected depends on the rate of sea level rise and the ability of ecosystems to adjust , and the extent to which habitats are prevented by migrating inland by coastal defences
Sea defences here are need substantial investment if they are to be effective. Many were constructed in the 1950’s following the storm surge of 1953 which killed over 300 people. Most at risk is the area between the river Humber and the Thames estuary. This stretch of coast has a history of flooding, and tidal surges measured at London bridge have been increasingly steady.
On the other hand, high insurance premiums are an effective way of dissuading peoples from moving into areas at risk from sea level rises. In rural coastal areas, under the governments habitat scheme, farmland is being allowed to become salt marsh.
Sea Level Change Map

17. EXAM QUESTION
Discuss the impact(s) of rising sea levels on coastal environments (15)
Discuss the impact(s) of rising sea levels on coastal environments (15)
NASA Quiz