Abrupt climate changes during the Last Glacial Period, some 115,000 to 11,700 years ago, happened at the same time across a region extending from the Arctic to the Southern Hemisphere subtropics, new research has revealed.
The study, led by University of Melbourne PhD student Ellen Corrick and published today in the journal, Science, found that rapid warming events over Greenland were linked to simultaneous temperature increases across continental Europe, and changes in rainfall in the Asian and South American monsoon regions.
"Some of the largest and most abrupt climate changes in Earth's geological recent past occurred during the Last Glacial Period, a cold interval that extended between 115,000 and 11,700 years ago," Ms Corrick said.
Greenland ice cores recorded more than 25 abrupt warming episodes during this period. These so called 'Dansgaard-Oeschger events' were associated with increases in air temperature over Greenland of up to 16°Celsius, sometimes in a matter of a few decades.
Researchers say the findings provide important information for testing numerical models used to predict future climate changes and demonstrate that profound climate changes can occur simultaneously, highlighting the unstable nature of the climate system.
Co-author, University of Melbourne Associate Professor Russell Drysdale, said: "Demonstrating synchrony in the climate response across such a broad region marks a major advance in the study of Dansgaard-Oeschger events. It allows scientists to improve understanding of how the events are propagated globally via the ocean and atmosphere system."
The research team, which involved scientists from Denmark, the UK, Germany, China, France and Switzerland, collated 63 individual climate records derived from stalagmites collected from caves across Europe, Asia and South America. The records represent over 20 years' worth of published research from scientific teams around the world.
Stalagmites - a type of cave mineral formation - preserve information on regional temperature and rainfall as they grow. Crucially, they can be dated very precisely, allowing the timing of climate events to be compared between records from different regions.
University of Melbourne Geochronologist Dr John Hellstrom, said that resolving the issue of timing has proved difficult because precisely dated records of past climate are required to determine exactly when the events took place.
"Such records are relatively rare, and it is only now that we have enough high-quality records to actually answer the question of synchrony," Dr Hellstrom said.
According to co-author Professor Eric Wolff from the University of Cambridge, the findings resolve a long-standing dilemma within the paleoclimate community, who study ancient climates.
"They provide confirmation of a persistent but, until now, unsubstantiated assumption that climate changes between the tropics and the Arctic were synchronous."