By Mike, 4 July 2013
Do you wonder why scientists are down in the Antarctic? One reason is to take ice cores, which keep a record of how the Earth’s climate has changed. To learn more (and make a tasty snack) try this totally cool activity!
Safety: When dealing with food, use clean hands and clean equipment.
Earth’s climate changes over time. The amounts of different gases, ash, dust and pollen in the atmosphere changes, as does the temperature of 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 and 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 sulfate – in the falling rain, snow and sleet (precipitation). This increase in sulfate 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 45%, methane has risen by nearly 250% and nitrous oxide has risen by 18%.
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