Contemporary sea level change

• What are glacial periods characterised by

  lower global temps and increase in amount of ice on land
• What are interglacial periods characterised by

  higher global temps and decrease in amount of ice on land
• what do glaciers and interlacers cause

  eustatic and isostatic sea level change
• 1. What happens at the start of glacial period

  Global eustatic fall in sea level

  - As glacial develops more and more water accumulates as ice in glaciers, ice caps and ice sheets.

  - Sea level falls for the whole planet.

  - Coastline advance all around the world
• 2. What happens at end of glacial period

  - Ice sheets, ice caps and glaciers form

  - local isostatic change in sea level

  - The huge weight of ice stored on land causes the land to sink

  - This isn't a global phenomenon it happens locally and only affects some coastlines
• 3. What happens at the start of the interglacial period

  -Global eustatic rise in sea level

  - the climate begins to get warmer.

  - eventually the ice masses on land begin to melt. This melted water returns to the sea and there is a worldwide rise in sea levels
• 4. What happens at the end of the interglacial period

  - some of the ice sheets, ice caps and glaciers have melted

  - local isostatic change in sea level

  - as the weight of the ice is removed from some land areas, they begin to move back up to their previous levels

  - This is called isostatic change/ readjustment
• What does isostatic refer to

  refers to the level of land- local
• What does eustatic refer to


  the rising and falling of sea levels- global
• What is thermal expansion

  Happens when water gets warmer, which causes the vol of the water to increase.

  - Thermal expansion exacerbates the sea level rise caused by eustacy, isostacy and tectonic movement
• What is tectonic subsidence (sinking)

  The sinking or downward movement of the Earth's crust due to tectonic processes
• What is an example of tectonic subsidence (sinking)

  Banda Aceh near Indo- Australian and Eurasian tectonic plates had some of its land subside by up to 1 metre as a result of a earthquake.

  - This sudden subsidence led to an increase in sea levels in those areas as the land dropped closer to ocean surface
• What is tectonic uplift

  refers to the rising of the Earth's crust due to tectonic forces
• What is an example of tectonic uplift

  Turakirae Head, New Zealand experience tectonic uplift where the land is gradually raised due to collision and movement of plates which cause land to be elevated which can lead to the appearance of a 'fall' in sea levels locally, even if global sea levels are rising