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Learning about the ancient past from ice
Did you know that?
Ice Cores can give us information about past environments, with records dating back for about 800,000 years in Antarctica and 120,000 years in Greenland. The ice cores are several kilometres long and need to be cut into sections and stored and analysed.
Ice cores can tell us about many different things:
- Climate cycles: Scientists can learn more about the climate during ice ages and the periods between them. We can see from the ice cores of Antarctica that temperatures in surface air have passed 10°C
- Sea level: By looking at isotopes of oxygen it is possible for scientists to estimate how much water was stored in the ice sheets and how much was in the sea which affects sea level. In cold periods water is stored in ice and sea level is low, whereas in warm periods some of the ice melts and sea level rises.
- Oxygen, CO2 and CH4 levels: Bubbles of air inside the ice are from the atmosphere when the ice was formed. So, from ice cores scientists can see how greenhouse gases have changed. By looking at how the concentrations of greenhouse gases have changed at the same time as temperature it is possible to predict how current and future concentrations of greenhouse gases will affect our future temperatures.
- Volcanic activity: Volcanic eruptions can be seen as lines in the ice caused by materials from the volcanos known as tephra.
Get Active!
Make your own ice core!
You will need:
Instructions
In a clean, long can (like a Pringles can), add a small amount of water, approximately 100ml, and mark where you fill it up to on the outside of the can.
Put the can in the freezer, standing upright. Freeze the layer completely.
Add the cocoa/sugar liquid mix, mark the can and then freeze again.
Add another layer of water and add jelly worms, mark the layer on the outside of the can and then freeze the layer.
Repeat however you like but make sure you mark where each layer finishes on the outside of the can so you can remember which layer is which.
When full and completely frozen, take the can out of the freezer and peel off the can's cardboard.
Examine your ice core. Each 2cm is a layer of 1,000 years of activity. Draw a replica of your ice core in the diagram below. There should be a total of approximately 10 layers or 10,000 years' worth of activity.
Then, break the ice core and see what organisms you can find recording where in the ice core they were found!
Following questions:
1
Are there any weather patterns in your core? E.g. more precipitation in one period or decreased temperature (giving a thicker ice layer).
2
In your ice core, the cocoa mix is like sediment or ash in a real ice core. Where might that sediment come from? Are there any natural events that would produce this?
3
Can you excavate any organisms from your ice core?
Draw your ice core below:
Teacher's Key:
From the stable isotopes of oxygen in the bubbles, scientists can understand how climate changed in the past. As warming has tracked the concentrations of greenhouse gases in the bubbles, scientists can predict how the climate could change in the future as the greenhouse gases increase.
E.g. more precipitation during one time period. If there is more water than anything else within one layer, there was a lot of precipitation during that time period or it colder with less melt. Dirt and debris could indicate more volcanic eruptions, forest fires and pollution during that time period.
Are there any natural events that would produce sediment? What about man-made pollutants? The sediment could be from the mountain sides above the glacier. Pollutants from wildfires and volcanic eruptions can also form layers in the ice. The volcanic sediment helps scientists to date their ice cores back to known volcanic eruptions. Dust could have blown from other nearby countries during a wind storm. Wind can even be identified in an ice core by an increased amount of salt being present. This information can tell scientists about wind speed and direction by using the ice-coring site as a reference to the nearby sea. Look out for air bubbles in the ice core – that could contain greenhouse gases!
Can you run as fast as a glacier surge?
How fast does a glacier surge move?
Although most glaciers are retreating (getting shorter), some glaciers periodically advance. For example, some glaciers "surge" (move forward). The rate of surge can be 10 to 100 times faster than the glacier normally moves. Surges can happen in cycles between 15 and 100 years. Average surge speed can be up to 15-20 meters a day compared with their usual movement of just a few centimetres a day!
The world's fastest moving glacier, Jakobshavn Isbrae in Greenland moved at a rate of 46m/day in the summer of 2012. Jakobshavn Isbrae is a whopping 64 kilometres long and approximately 1.5 kilometres thick glacier.
The world's fastest moving glacier, Jakobshavn Isbrae in Greenland moved at a rate of 46m/day in the summer of 2012. Jakobshavn Isbrae is a whopping 64 kilometres long and approximately 1.5 kilometres thick glacier.
A Greenland glacier. Photo: Terry Callaghan
Following questions:
Answer: 16,79 km
Answer: 3.2 cm