This seawater is 20,000 years old and has remained intact since the last ice age


Twenty thousand years ago, life on Earth was much cooler. It was the end of a 100,000-year ice age, also called Last Glacial Maximum, and huge ice sheets covered much of North America, Northern Europe and Asia. (If they had existed at that time, the city of New York, Berlin and Beijing would have been buried in the ice).

Scientists are accustomed to studying this cold spell in Earth's history by observing things like coral fossils and seabed sediments, but now a team of marine researchers may have found a part of the past that makes everyone else come out of the water: a real sample of sea water of 20,000 years, squeezed from an ancient rock formation in the Indian Ocean.

According to the researchers, who described the finding in a study to be published in the July 2019 issue of the journal Geochimica et Cosmochimica Acta, this finding represents the first direct remnant of the ocean as it appeared during the last ice age of the Earth.

The researchers found their watery prize while drilling sediment samples from the underwater limestone deposits that make up the archipelago of the Maldives in South Asia. After transporting each core to its research vessel, the team cut the rock like a cookie dough tube and put the pieces in a hydraulic press that squeezed any moisture from the pores. [Photos: Traces of an Ancient Ice Stream]

Assistant professor Clara Blättler with a jar of sea water dating from the last Ice Age, approximately 20,000 years ago.

Assistant professor Clara Blättler with a jar of sea water dating from the last Ice Age, approximately 20,000 years ago.

Credit: Jean Lachat

When the researchers tested the composition of these samples of fresh pressed water on board their ship, they were surprised to discover that the water was extremely salty, much saltier than the Indian Ocean at present. They did more tests on land to see the specific elements and isotopes (versions of elements) that made up the water, and all the results seemed out of place in the modern ocean.

In fact, everything about these water samples indicated that they came from a time when the ocean was significantly more salty, colder and more chlorinated, exactly as it is believed to have been during the Last Glacial Maximum, when the ice sheets aspired water from the ocean and shed Sea levels hundreds of feet below current levels.

"Of all the indications, it seems pretty clear that we now have a real part of this 20,000-year-old ocean," study lead author Clara Blättler, an badistant professor of geophysical sciences at the University of Chicago, said in a statement.

If these results retain water, the new samples provide the first direct glimpse of how the ocean reacted to the geophysical changes of the last ice age. Blättler said that this understanding could lead to improved climate models to help understand our own changing world, since "any model that builds on climate has to be able to accurately predict the past."

Note: At the time of publication of this article, no one had yet requested to drink the juice of the ancient ocean.

Originally published in Living science.

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