Sea ice acts as ’pacemaker’ for abrupt climate change

Substantial variations in past sea ice cover in the Norwegian Sea were instrumental for several abrupt climate changes in large parts of the world, researchers have found. An international study involving researchers from the UK, Norway, Germany Australia, South Korea and the US has confirmed that changes in sea ice cover in the Norwegian Sea played a key role in driving abrupt climate change events between 32,000 and 40,000 years ago, where global temperatures shifted as much as 15 degrees Celsius. The results , reported in the journal Science Advances , indicate that initial sea ice reduction started before the abrupt warming over Greenland, and that sea ice expansion started before the end of the warm periods in Greenland. The Arctic sea ice is a key element of the global climate system and the strong ongoing warming of the Arctic Ocean can have major impacts on the stability of the Greenland Ice Sheet, first and foremost accelerated sea level rise. The Nordic Sea system and its water column structure during the last glacial cycle is the closest analogue to the present-day Arctic Ocean, which makes it a perfect natural laboratory to understand the role of rapid disappearance of regional sea ice on abrupt warming on the Greenland Ice Sheet. The last glacial period, 10,000-100,000 years ago, was marked by repeated abrupt climate changes with global implications. Within a matter of decades, temperature shifts of as much as 15 degrees Celsius occurred around Greenland, but the mechanisms driving these changes -known as Dansgaard-Oeschger events - are not fully understood.