Over the last year, we’ve talked about a lot of ways scientists are trying to measure both historic and current climate changes. From looking at tree rings in fossilized trees to looking at ice layers in Greenland ice, researchers travel the world, looking for old things that record seasonal cycles. 

In new research appearing in Geophysical Research Letters, researchers led by Dominic Winski have looked at the salt deposits left behind by melting sea ice to get new data. Essentially, over the winter, sea ice is blown inland by storms: the more sea ice, the more gets blown inland. When that ice melts, it leaves behind salt in proportion to the amount of sea ice. That salt is then captured in ice cores. 

According to their paper: Ice core data across Antarctica show increasing sea salt concentrations since 11,400 years ago, representing cooling and sea ice expansion, particularly between 8,000 and 10,000 years ago. Between 5,000 and 6,000 years ago, a drop in sea salt indicates an abrupt reduction in sea ice cover in the South Atlantic. Interestingly, paleoclimate data suggest that sea ice was more extensive in the North Atlantic at this time, indicating a linked and opposing sea ice signal in the North and South Atlantic most likely due to changing ocean circulation. 

This finding is consistent with models that predict that changes in sea ice and glaciation will fundamentally change ocean currents. To those of you who feel like the last few years have gotten weirder and weirder? You are right. We are alive to see our world changing, and scientifically, this is an amazing opportunity, but I think it is an opportunity all of us would happily have passed up.

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“Seasonally Resolved Holocene Sea Ice Variability Inferred From South Pole Ice Core Chemistry,” Dominic A. Winski et al., 2021 April 6, Geophysical Research Letters