Posted on 03/09/2019 12:38:24 PM PST by BenLurkin
For several million years, the Earth cycled through ice ages at a regular pace, but then, 1.25 million to 700,000 years ago, something changed: ice ages went from lasting 40,000 years to 100,000.
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By looking at the microscopic shells of microorganisms called foraminifera, Adam Hasenfratz of the Geological Institute in Zürich, Switzerland, and colleagues, find evidence of a reduction in deep water circulation, causing less carbon dioxide to be released into the air.
Oceanic changes in the Antarctic Zone could have ensured “that glacial conditions persisted despite orbital changes to the contrary”, the study says.
The new research, presented in the journal Science, suggests a solution to the mystery surrounding what is known as the mid-Pleistocene transition (MPT). Recommended
To determine the prehistoric ocean circulation, Hasenfratz and his colleagues looked at sediment samples accumulated over 1.5 million years and analysed trace elements and oxygen isotopes from preserved foraminifera shells.
The results indicated that during glacial periods after the MPT the upper regions of the Southern Ocean became fresher and cooler, while its depths grew more saline.
(Excerpt) Read more at cosmosmagazine.com ...
+1
Chuckles. Have a great day FReeper.
Agree
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