COASTS: Sea Level Changes Flashcards Preview

AS/A-Level Geography > COASTS: Sea Level Changes > Flashcards

Flashcards in COASTS: Sea Level Changes Deck (16)
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1
Q

Eustatic changes

A

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

2
Q

Isostatic changes

A

Local sea level changes caused by vertical movements of the land relative to the sea.

3
Q

What are the 2 main causes of eustatic change?

A

Changes in climate

Tectonic movements

4
Q

How can climate change lead to eustatic sea level change?

A
  • Increase in temp causes ice sheets to melt.
  • Also causes water to expand.
  • Increases sea level further.
5
Q

What are the main causes of isostatic change?

A
  • Uplift or depression of Earth’s crust due to accumulation or melting of ice sheets.
  • Subsidence of land due to shrinkage after abstraction of ground water.
  • Tectonic processes.
6
Q

What can cause variation in sea level?

A

Tidal change.

Onshore winds.

Low atmospheric pressure systems.

7
Q

When was the last glacial period?

A

Approx. 110,000 to 12,000 years ago.

8
Q

When was the last glacial maximum?

A

Approx. 21,000 years ago.

9
Q

At the last glacial maximum, how much lowere was the sea level?

A

About 130m lower than present.

10
Q

When did the sea level reach its present level?

A

Approx. 4000 years ago

11
Q

What has happened to sea level over the past 4000 years?

A

It has fluctuated around its present value.

12
Q

What has happened to sea level since about 1930?

A

It has been rising.

13
Q

At what rate is global sea level rising each year?

A

Almost 2mm each year.

14
Q

If greenhouse gas emissions remain high during the 21st century, what is predicted to happen?

A

Sea levels will rise 8-16mm a year by 2100.

15
Q

What is likely to increase due to climate change?

A

Storm frequency and intensity due to changes in ocean circulations and wind patterns.

16
Q

What will the impacts of sea level rise be on coastal areas?

A
  • More frequent & coastal flooding, Kings Point in New York flood risk has doubled.
  • Submergence of low-lyging islands, eg. Maldives will be submerged by increase of 0.5m.
  • Changes in coastline, eg. 0.3m increase in sea level will mean 8000km2 of land in Bangladesh will be lost.
  • Contamination of water sources and farmland.