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Fossils Help Determine Ocean’s Role in Last Ice Age

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Scientists from The University of Tasmania’s Institute for Marine and Antarctic Studies and Simon Fraser University have used the fossil record to pull together the first global database of ocean temperatures over the past 125,000 years in order to explain why carbon dioxide levels were low at the time.

The study, published in Earth and Planetary Science Letters, combined ocean temperature records with other studies to show how carbon dioxide took different paths into the deep sea during different phases of the ice age.

“This study shows for the first time how temperatures changed across the whole ocean as the earth entered the last ice age,” said lead author A/Prof Karen Kohfeld. “This new understanding of ocean temperature changes hints at some important thresholds in the climate system.

“It’s clear that some parts of the system, such as sea-ice around Antarctica, responded rapidly when the ocean cooled. Other parts, like deep ocean circulation, changed very slowly and needed a nudge of extra cooling to push the system into a new state, a whole 30,000 years after the sea-ice changed.”

With direct measurements only providing ocean temperatures for approximately the past 100 years, the researchers used chemical and biological clues left by tiny fossils in mud from the sea floor to understand past temperatures. Past ocean temperatures can be...

The full text of this article can be purchased from Informit.