Science

Research finds that the Arctic Sea remains open

According to new research challenging long-standing scientific debates, the Arctic Sea will never freeze solids under a huge ice shelf.

Instead, even though glaciers cover most of the Northern Hemisphere, the region maintains seasonal sea ice and patches of open waters that support marine life.

Scientists from Norway, Britain and Germany analyzed 750,000-year-old ancient seabed sediments in two major Arctic regions. Their findings published in “Scientific Advances” contradict the theory that during extreme glacier times, a kilometer-thick ice shelf once covered the entire Arctic ocean.

Tiny fossils tell an ancient story

The team studied the microchemical characteristics of algae left behind sediment cores in the northern Svalbard and central Nordic oceans. These algae act like ancient weather reporters – some species only grow in open water, while others thrive under seasonal sea ice that forms and melts every year.

“Our sediment core shows that marine life is active even during the coldest periods,” said Jochen Knies, principal author of the Norwegian Arctic University. “This tells us that there must be fresh water and open water on the surface. You won’t see the entire Arctic locked under a kilometer-thick ice.”

A crucial clue comes from a molecule called IP25, which is produced only by algae that live in seasonal sea ice. Throughout the sediment record, its consistent presence suggests that sea ice comes and forms permanent freezing barriers with seasons rather than permanent.

Computer model support evidence

The team used advanced climate modeling to test its geological discoveries. Computer simulations of two particularly rigorous periods – the last glacier up to 21,000 years ago and the deeper freeze 1,400,000 years ago – confirmed the sediment recommendations.

“These models support what we find in the sediment,” Knies explains. “Even during these extreme glaciers, warm Atlantic waters still flow into the Arctic gateway. This helps prevent some parts of the ocean from freezing completely.”

Simulations show that ice is not static during glacial times. Instead, it changes seasonally, creating openings that sunlight can penetrate and marine life can flourish.

Main research results

  • Continuous biological activity: Marine algae and plankton survived all glacial periods studied
  • Seasonal Ice Mode: Sea ice forms and melts every year, rather than continues throughout the year
  • Atlantic influence: Warm currents continue to flow into Arctic waters during the Ice Age
  • Limited ice shelf evidence: About 650,000 years ago, there was only one short time showing potential ice shelf conditions

Rethinking the history of Arctic ice

Some scientists believe that huge underwater ridges and seabed scars indicate that a huge ice shelf was once scraped across the Arctic seabed. But the study provides another explanation: These characteristics may come from huge icebergs that erupt from ice sheets around the edge of the Arctic and float across the ocean.

These floating icebergs, partly stretched over 800 meters, may dig out the seabed while maintaining mobility rather than forming a solid continent across the ice shelf.

The team did find evidence of a possible exception 650,000 years ago, when biological activity dropped sharply. However, even this event is temporary, rather than the lasting ice shelf predicted by some models.

Climate insights into today’s world

Understanding how the Arctic performs under extreme conditions can help scientists predict its future because global temperatures rise. Gerrit Lohmann, co-author of the Alfred Wegener Institute, noted that the study “helps us understand what the ice sheet and ocean dynamics are likely, not what.”

The results show that the Arctic oceans maintain their basic cyclic patterns even during the coldest period of the Earth. This resilience provides insights on how the region responds to today’s rapid warming, despite the reverse turn – from seasonal ice to increasingly ice-free conditions.

The study represents part of the European Research Council’s “Enter Blue” project, which aims to understand the changes in polar oceans during the geological era. As Knies said, “We need to know how the Arctic behaves under pressure and where the inclination of the Arctic lies – how the Arctic responds to a warm world.”

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