A new study on Greenland ice cores shows that Arctic sea ice loss in the period 30-100,000 years ago was associated with major oscillations in high latitude climate. During this period, Greenland temperatures repeatedly increased by up to 16°C in less than a century, followed by more gradual cooling. The results are published today (Monday 11 February) in the journal Proceedings of the National Academy of Sciences (PNAS).

The team, led by Dr Louise Sime from the British Antarctic Survey, includes Dr Rachael Rhodes an ice core scientist who recently joined CAPE at Northumbria. Dr Rhodes explains what the study involved:

“We studied data from ice cores drilled in Greenland, focusing on records of oxygen isotopes that are the poster-child example of abrupt climate change. We compared these records to output from sophisticated climate models able to simulate how the oxygen isotopic mix of the ice changes with climate and sea ice conditions.”

From this Dr Rhodes and the team determined that rapid, extensive sea retreat was a hugely important control on the oxygen isotope signals. This is a significant result because the abrupt climate warmings, called Dansgaard-Oeschger events after the two scientists who first discovered them, are some of the fastest and largest abrupt climate changes ever recorded. Now that we better understand how sea ice loss is imprinted on Greenland ice cores, we move closer to deciphering between competing theories about what actually triggered these remarkable climate events.

Even though Dansgaard-Oeschger events occurred in an ice age when the Arctic was much colder than it is today, Dr Rhodes says it is critical to learn about the climate impacts of past Arctic sea ice loss given that Arctic sea ice extent is currently decreasing in our warming world.

Impact of abrupt sea ice loss on Greenland water isotopes during the last glacial period by Louise C. Sime, Peter O. Hopcroft, Rachael H. Rhodes is published in the Proceedings of the National Academy of Sciences here.