Swiss researchers have been able to accurately reconstruct the climate of the past 50,000 years studying stalagmites from Turkey.
Scientists at Bern University measured rapid climate fluctuations – known as Dansgaard-Oeschger events – when temperatures suddenly rose by up to ten degrees Celsius within a few decades.
It is believed the events could reflect changes in the North Atlantic ocean circulation – perhaps triggered by an influx of fresh water.
Up until now, measurements of about two dozen events that took place during the last ice age were based on ice core samples from Greenland.
However, the researchers said dating the temperature swings using ice cores is not very accurate.
The samples from three stalagmites taken from two caves in northwestern Turkey enabled the scientists to date the changes to within a period of 140 years, compared to 800 to 1,000 years using ice cores.
The head researcher, Dominik Fleitmann, said the new findings showed that the temperature swings did not happen on a regular basis (every 1,500 years) as had been previously thought.
Fleitmann said this means it is unlikely that the sudden rises in temperature are linked to periodic increases in solar radiation, as had been speculated.
swissinfo.ch and agencies