New research suggests that sudden temperature fluctuations in Greenland and Antarctica over the last ice age might have been interlinked. By studying a newly uncovered and highly detailed ice core, researchers have observed that there was a clear “lag” between the two changing climates.
The researchers were investigating the unstable nature of Greenland’s climate during the last ice age when they noticed that there were a number of large and abrupt changes in mean annual temperatures. Moreover, each of the said changes took place within a matter of decades and was caused by Dansgaard-Oeschger events – rapid climate fluctuations that occurred 25 times during the last glacial period. The temperature changes in Antarctica showed an opposite pattern. Greenland warmed when Antarctica cooled, and vice versa.
The study of new ice cores also reveals that the sudden climate changes occurred in Greenland first. The corresponding changes in the Antarctic climate were delayed by approximately 200 years. There were a total of 18 abrupt climatic events over the past 68,000 years.
“The fact that temperature changes are opposite at the two poles suggests that there is a redistribution of heat going on between the hemispheres,” said Christo Buizert, lead author of the new study, in a news release. “We still don’t know what caused these past shifts, but understanding their timing gives us important clues about the underlying mechanisms.”
The mechanisms behind these changes are fascinating, as the 200-year delay points towards the involvement of an oceanic mechanism. How did scientists reach that conclusion? Well, the long delay suggests that it is water, because if it happened through the atmosphere, the response would have occurred in a matter of just years or decades. There is a strong possibility that the Atlantic Meridional Overturning Circulation (AMOC) is involved.
“This ocean circulation rings warm surface waters from the tropics to the North Atlantic,” added Buizert. “As these water masses cool, they sink to the bottom of the ocean. This happens right off the coast of Greenland, and therefore Greenland is located in a sweet spot where the climate is very sensitive to changes in the AMOC.”
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