Flashcards in 2B.7 Deck (26)
What is isostatic change?
When land is changing relative to the sea locally which is due to isostatic rebound
- ice leaving ground
What is eustatic change?
When the sea changes relative to the land (global) due to melting ice from the poles
- more water in oceans
How do tectonic affect sea level?
Land can be pushed up by plates in a series of earthquakes which an displace the sea-bed leading to post glacial rebound
Eg Iceland = Surtsey has risen due to volcanic activity
How does accretion affect sea levels?
The deposition of sediment in rivers, estuaries or deltas can weigh down the crust and also cause sinking (subsidence)
Eg Thames estuary
What are submerging coastlines produced by?
Eustatic sea level change
What are emergent coastlines produced by?
Isostatic readjustment / rebound
Who monitors climate change?
The IPCC intergovernmental panel on climate change
—> show that it fluctuated in 1850s
What are predictions of sea level change?
Lowest = 28-61 cm rise
High = 52-98 cm rise
What contributes to sea level change?
Melting of glaciers - 27% so far,
Sea level rising 3mm a year which is seasonal (winter = cumulative budget) summer = melts
Melting of ice sheets eg 10% in Antarctic, 15% in Greenland
Why is there debate about sea level rise?
Unclear about how much thermal expansion
Unclear at speed of melting
What areas in the world are at most risk?
What are causes of coastal retreat?
How do human causes impact recession rates?
- Alters Natural processes
- defences reduce sediment
- offshore dredging eg Hallsands and Admiralty
- chooses SMP on CBA
How do sub-aerial processes cause retreat?
—> moves sediment away
—> influenced by season changes
How do winds add to coastal retreat?
Dominant winds give off energy to waves which fluctuated adding to the dynamic coastal area ie foreshore.
Coasts experience mass erosion during winds
How do tides increase recession?
High tides = waves reach back shore and eroded
- destructive waves cause maximum erosion
How do weather systems lead to increased recession?
Low pressure = rising air = strong winds causing storm surges
In winter there are stronger depressions and larger more destructive waves
Higher temperature = more erosion = energy levels
What is a transboundary river?
River that traverses across two or more countries eg the Nile delta main river.
What are facts about the river Nile?
More salt in delta due to sea level rise = flocculation
2million hectares of land lost
6million people displaced
30% of Alexandrian population displaced
240km of Nile delta is Eastern Mediterranean
Will destroy tourism defences agriculture and settlements
95% of Egypt live near delta
What is coastal squeeze?
Population forcing areas to develop near coasts or rivers. eg Mediterranean.
What is a raised beach?
Former beach now above the high tide line which contain several layers eg Forthy, Clyde and Tay in eastern Scotland.
What is a fossil/relict cliff?
Near vertical slope initially formed by Marin erosion but now inland eg Vik in South Iceland.
These may still have coastal features eg Stack or cove.
What is a ria?
A flooded river valley
What is a fjord?
Flooded glaciated valley?
What is an example of a fjord?
In Norway, NZ, Canada.