2B.7 Flashcards
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?
Thermal expansion
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?
Maldives Bangladesh Netherlands New York Southampton Mumbai
What are causes of coastal retreat?
Human causes Sub-aerial processes Wind direction Tides Weather systems
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?
Weakens rocks
Mass movements
—> 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