In order to know why an ice age ends, we need to know when it ended. Now, new research is working to solve one of the enigmas in palaeoclimatology.
Our climate has been much colder than it is at present for most of the last million years. Ice sheets, several kilometres thick, once covered large parts of North America and Eurasia. But, every 100,000 years or so, the climate warms rapidly to conditions similar to today during intervals called ‘terminations’.
The discovery of ice ages in the recent geological past goes back to the 1700s. Field scientists from Europe noted huge piles of sediment deposited in valleys and plains around the Alps. These sediments were unusual because they consisted of rock types outcropping tens to hundreds of kilometres away.
Originally attributed to Biblical floods, these deposits could only have reached their final destination on glaciers, which must have been many times larger than their current size.
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Image via University of Melbourne
