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A new study analyzing sediment cores from the North Atlantic has revealed a strong connection between deep ocean current shifts and a major period of global cooling in the Northern Hemisphere approximately 3.6 million years ago. This research marks the first time scientists have linked changes in sediment composition to disruptions in deep water circulation during that epoch. Led by Dr. Matthias Sinnesael of Trinity College Dublin and Dr. Boris Karatsolis of Vrije Universiteit Brussel, the study—published in Nature Communications—examined sediment records from multiple sites east of the mid-Atlantic ridge. These cores revealed clear signs of ocean current alteration, while comparable sites west of the ridge showed no such change. This asymmetry suggests a major reorganization of deep water flow, which likely played a key role in the onset of global cooling. The findings offer new avenues for studying how shifts in deep ocean circulation affect global climate, ocean salinity, and the expansion of ice sheets. They also provide important historical context for today’s climate challenges.
"Over recent decades, humanity has experienced increasing consequences of global warming—from rising seas and intense heat waves to extreme flooding," said Dr. Sinnesael. "Climate is the long-term average of weather patterns, shaped by both short-term events and massive geological or atmospheric forces acting over millions of years." Understanding how past climate systems functioned is vital for distinguishing natural climate variability from human-driven changes. Researchers often investigate major systems such as ice sheets, river basins, and ocean currents to find clues about Earth's climatic past.
One of the most influential of these systems is the global ocean conveyor belt, which transports heat across the world’s oceans. Its surface component includes the Gulf Stream, which brings warm tropical waters to northern latitudes, giving western Europe its relatively mild climate. The deeper segment of this conveyor belt involves three major southward-flowing currents: Iceland Scotland Overflow Water (ISOW), Denmark Strait Overflow Water (DSOW), and Labrador Sea Water (LSW). Together, they form what is known as North Atlantic Deep Water (NADW).
Dr. Karatsolis emphasized growing concerns about the stability of this conveyor belt. "There’s increasing evidence that it is slowing due to warming and ice melt, which could have serious consequences for ecosystems and human societies worldwide."
To better understand what lies ahead, the research team focused on reconstructing how this system behaved in the past—specifically during a time when Earth’s temperature and CO₂ levels were higher than today, but similar to projections for the coming centuries. By decoding the behavior of ocean currents during that ancient period, the team hopes to shed light on the future of our planet’s climate system and improve our ability to predict its response to ongoing environmental change.
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Post time 2025-05-19 02:29:10