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Where did all this ice come from?

29 Nov 2023 | Science Notes

H/t No Tricks Zone we have learned of a new study led by scientists from Kiel University in Germany that reconstructs temperatures and ice coverage of the North Atlantic off the Labrador coast over the past 9,000 years. To measure that far back the scientists traveled out on the Labrador shelf and dug up cores from deep in the ocean floor. It turns out that certain unique biological compounds form in sea ice and from there settle to the bottom of the ocean, and variations in the density of these compounds give scientists clues about the amount of sea ice covering the ocean in millennia past. And since we all know the world is the hottest its ever been, that must mean there’s far less ice now than in the past, right? Well, no. It’s the other way around. How strange.

The scientific team found that about 9,000 years ago the sea ice in the Labrador Sea was in retreat and there was a lot of open water. Around 8,500 years ago as the melting continued, the Hudson Bay Ice Saddle Collapse allowed “the Lake Agassiz outburst” in which this body, roughly the size of the Black Sea, flowed into the North Atlantic, further driving down sea ice coverage. From 8,900 to 7,500 years ago open water increased, but around 8,200 years ago the “ultimate demise of the Laurentide Ice Sheet” led to a sudden cooling of the North Atlantic as another surge of accumulated meltwater reached the ocean basin.

From then until about 6,500 years ago sea ice coverage steadily declined as the North Atlantic warmed up into the mid-Holocene Climate Optimum. The phase of relatively low sea ice and warm temperatures continued until about 3,000 years ago. But the past 3,000 years have been marked by steady cooling and increased sea ice coverage.

The above diagram is adapted from Kolling et al. and shows the sea ice marker record (gray shading) going back in time (so left is present time and right is 9,000 year ago). As you can see the most recent time interval is characterized by historically high sea ice levels.

You might even start to think we could be heading into another ice age. Now that would be a climate emergency.

3 comments on “Where did all this ice come from?”

  1. But of course, that little dip at the very end of the graph is all our fault. /sarc

    Less ice is bad why exactly?

  2. Given the duration of the last 4 interglacial periods, the likelihood of the return of the glaciers is, in geological time, imminent. It's at least as likely as the CAGW hypothesis. Perhaps some AGW can delay it a little more.

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