Arctic ice formed about 45 million years ago – roughly 14 million years ahead of previous predictions – according to new research published in Nature. An international team of scientists, including Brown geologist Steven Clemens, says this startling evidence shows that glaciers formed in tandem at Earth’s poles, providing important insights into global climate change.
Cold, hard facts
An armada of three ice-breakers kept abundant ice at bay so that ocean-drilling scientists could collect sediment core samples from beneath the Arctic sea floor. Evidence from the core samples suggested that glaciers had formed in the Arctic 14 million years earlier than scientists had thought. Image: IODP/ECORD Science Operator
For the first time, scientists have pulled up prehistoric geologic records from the frigid vault of the Arctic Ocean. One of the findings, evidence of glacial Arctic ice from 45 million years ago, recasts a critical chapter of global climate history.
The evidence – pea-sized pebbles locked inside a 430 meter-long sediment core – shows that glaciers formed in the Arctic Ocean about 14 million years earlier than geologists had thought. This means that the immense sheets of ice at the Earth’s poles formed simultaneously, something researchers call “bipolar symmetry” in one of three reports on Arctic ice highlighted on the cover of Nature.
Clemens said the major finding – evidence of ice-deposited debris 45 million years ago – came in the form of pebbles. Why? Glaciers scrape across the land as they grow, carrying ground rock with them. When glaciers reach the sea, some of that ice shears off and forms icebergs, which shed pebbles as they melt.
This evidence of synchronous ice formation in the Arctic and Antarctic in the past may help bolster the evidence of “bipolar symmetry” today. In recent months, scientists have reported rapid melting of the worlds’ ice, from the Antarctic ice sheet to Greenland glaciers. Many scientists believe the shrinking ice is linked to a sharp increase in greenhouse gases.
“Bipolar ice forms together and melts together,” Clemens said. “Carbon levels are a huge driver of ice volume and global climate change, at all time scales.”
The International Ocean Drilling Program supported the research. The program receives primary funding from the National Science Foundation and Japan’s Ministry of Science, Education, Culture, Sports, Science and Technology. The ACEX platform operations were funded by ECORD, the European Consortium for Ocean Research Drilling, a contributing member of IODP. As an affiliate member, the People’s Republic of China also supported the expedition.
Wendy Lawton | EurekAlert!
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