You will remember from Chapter 13 that temperature is measured using a thermometer. However, we only began to use thermometers to record temperature data in the last hundred years. This means that there are no reliable weather records before the 1900s detailing the earth’s weather patterns, such as its temperature.
In order to piece together weather data from before this time, scientists analyse sediment cores taken from ocean and lake floors and from frozen ice cores.
Greenland Ice Sheet
Antarctic Ice Sheet
Ice cores are cylinders of ice drilled out of an ice sheet or glacier.
As layers of fresh snow fall and sediment become buried, they trap and preserve (store) evidence of the global temperature experienced at that time of the burial. Investigating the physical and chemical make-up of the ice core can tell us of past changes in climate.
Most ice core records come from Antarctica and Greenland. The oldest continuous ice core records are from Greenland and go back 130,000 years.
Light and dark bands alternate like tree rings in this ice core from Greenland. The longest ice cores extend to 3 km or more in depth.
Each silver tube on these shelves contains a one- metre-long section of an ice core. They are stored at a temperature of –36°C.
Go to YouTube and look up ‘National Ice Core Lab Stores Valuable Ancient Ice – Science Nation’ (2:31) to see how ice cores are extracted and stored.
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Climate Change
Ireland’s climate is
changing in line with global patterns. The temperature records show an average temperature increase in this country of 0.7oC between 1890 and 2008.
