Discover a Changing Climate in an Ice Core

Climate in an Ice Core

The ice cylinders that make up this nucleus contain unique detailed information about past environmental conditions , such as atmospheric concentration of greenhouse gases, surface air temperature, wind patterns and average ocean temperature.

How to Discover A Changing Climate?

Make an ice core in your freezer that you can carefully study later (that means eat). An ice core is like a time machine into the past. Some ice in the Artic, Antarctica and in glaciers has been frozen for hundreds and thousands of years and can tell scientists what the climate was like all those years ago. The ash and gas of volcanoes can also be found trapped in the ice, telling us the size of past eruptions and when they occurred.

You will need

  • Water
  • A freezer
  • An iceblock maker, plastic cups work well too
  • Lemonade (the fizzy, carbonated kind)
  • Food colouring
  • Fruit juice
  • Cocoa
  • A small mixing bowl

What to do

  1. Mix the components of each layer together following the instructions below, and pour the mixture into the iceblock mould, filling up a third of the mould each time.
  2. Make and freeze each layer before adding the next, starting with layer one.
  3. When all three layers are frozen, you can eat it!

Layer one —A volcano has erupted and there is ash in the atmosphere. There is also pollen from flowering plants.

  • A cup of fruit juice. The pulp in the fruit juice represents pollen from plants found in the atmosphere.
  • A teaspoon of cocoa. This represents the ash and dirt in the atmosphere from a recent volcanic eruption.

Layer two — There is pollen in the atmosphere and carbon dioxide levels are increasing.

  • A cup of half fruit juice and half lemonade. The bubbles in the lemonade are bubbles of carbon dioxide gas that represent carbon dioxide gas in the atmosphere.

Layer three — There is a dramatic increase in human-made carbon dioxide and a volcanic eruption

  • A cup of lemonade. The bubbles of carbon dioxide in the lemonade represent the increased levels of carbon dioxide in the atmosphere.
  • A drop of red food colouring. The Earth is warming.

What’s happening?

The Earth’s climate changes over time. The amounts of different gases, ash, dust and pollen in the atmosphere changes, as does the temperature of the Earth.
In snowy areas, such as the Arctic and Antarctic, or on glaciers, snowfall freezes each year leaving a layer of ice as a record of that year’s snowfall. The frozen water in this ice record can tell us the approximate temperature of the Earth when the snow fell. Bubbles of air can also be trapped in the ice when it is frozen. When analysed, these small pockets of ancient air can tell us which gases and how much dust, dirt were in the air up to 800 000 years ago!
Ice cores are tubes drilled out from the ice, and can be up to three kilometres long. The ice cores are taken back to the laboratory so researchers can discover the information trapped inside.


Significant volcano eruptions in the past can be found and measured in ice cores. An erupting volcano will increase the amount of chemicals, such as sulphate, in the falling rain, snow and sleet (precipitation). This increase in sulphate can then be detected in the ice.
Researchers in Antarctica have found evidence for a large eruption that they think occurred in the year 1459 in an ice core taken from a place called Dome Summit South. Around 64 cm of snow falls at this site each year. You can find ice here that fell from the skies more than 80 000 years ago.
Ice cores can also tell us about out changing climate. Researchers have found that over the last 200 years the gas composition in the atmosphere has changed. The amount of carbon dioxide has risen by 37 per cent, methane has risen by 150 per cent and nitrous oxide has risen by 18 per cent.


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