Ice Levels Over Time Flashcards
What is an ice age?
When the earth goes through a cold period lasting for millions of years
During ice ages large masses of ice cover the earths surface
What was the last ice age and when did it begin?
The Pleistocene ice age and began around 2.6 million years ago
What is a glacial period?
À part of the ice age that are coller when the ice advances to cover more of earths surface
They last about 100,000 years
What are interglacial periods?
Un between glacial periods are warmer periods when the ice retreats to cover less of the earths surface
Lasts around 10,000 years
When was the last glacial period?
Began around 100,00 years ago
Ended around 10,000 years ago
Since the Pleistocene where has there been permanent sheets of ice?
Antarctica
Greenland
During the last glacial period what percentage of earth was covered in ice?
30%
What period are we currently in?
Interglacial
Began around 10,000 years ago
10% of earths land covered by ice
What are three sources of changing temperature evidence?
Chemical evidence
Geological evidence
Fossil evidence
How is chemical evidence used?
Chemical composition of ice and marine sediment change as uk temperatures change so can be used to work out how global temperature has changed in the past
How is chemical evidence tested?
Ice and sediment build up over thousands of years
Samples are taken at different depths showing temperature over thousands of years
Records show a record of fluctuating temperature which caused the ice to advance and retreat
What is geological evidence?
Some landforms we see today were created by glaciers in the past
Showing that some arenas which aren’t covered in ice now were in the past showing temperatures were lower
What is fossil evidence?
Remains of some organisms are preserved when they die creating fossils
Fossils show distribution of plants and animals that are adapted to warm and cold climates in the past
Using this we can tell which areas were warmer and colder
What’s the first thing that can cause an ice age?
Changes in the circulation of the atmosphere and the oceans
Wind and ocean currents help to circulate heat from the equator towards the poles
If those currents get disrupted then some areas could get very cold very quickly
What is the second cause of an ice age?
The earth sometimes receive less heat from the sun due to
- a decrease in the suns energy out put caused by sun spots
- an increase in atmospheric dust causes by volcanic eruptions
- a change in the earths orbit taking it further from the sun
