2023-09-15 10:31:34
The sediment core is extracted from the Ythan estuary. – UNIVERSITY OF LEEDS
MADRID, 15 Sep. (EUROPA PRESS) –
Geological samples from Scotland have identified a melting ice sheet as a probable trigger for a major climate change event just over 8,000 years ago.
The analysis could hold clues about how the current loss of ice in Greenland could affect the world’s climate systems.
More than 8,000 years ago, the North Atlantic and northern Europe experienced significant cooling due to changes in a major ocean current system known as the Atlantic Meridional Overturning Circulation (AMOC). This change also affected global rainfall patterns.
The influx of a massive amount of freshwater into the saltwater seas of the North Atlantic is believed to have caused the ‘breakdown’ of the AMOC.
The research team, led by the University of Leeds, sampled sediment in the Scottish Ythan estuary to get an idea of what was happening to sea levels more than 8,000 years ago.
By analyzing microfossils and sediment samples, they found that changes in sea level moved away from normal fluctuations of around two millimeters per year and reached 13 millimeters per year, with individual sea level events which caused a rise in water of probably about 2 meters in the Ythan estuary.
Analysis of the core samples provides additional evidence that there were at least two main sources of fresh water that drained into the North Atlantic, causing the changes in the AMOC, and not a single source as previously thought.
The opinion of many scientists was that the fresh water came from a giant lake, Lake Agassiz-Ojibway, which was the size of the Black Sea and located near what is now northern Ontario, which had flowed into the ocean.
Dr. Graham Rush, lead author of the study, said it’s a statement: “We have shown that, although huge, the lake was not large enough to account for all that water entering the ocean and causing the sea level rise that we observed.”
Instead, Rush and his colleagues believe that the melting of the Hudson Bay Ice Field, which covered much of eastern Canada and the northeastern United States, provided the injection of large quantities of water that was reflected in the core samples.
Thermal energy drives the global climate and that alteration of the ocean current had important ramifications throughout the world.
Temperatures in the North Atlantic and Europe fell by 1.5 to 5 degrees C over about 200 years, and other regions experienced above-average warming. Rainfall levels also increased in Europe, while other parts of the world, such as parts of Africa, They experienced drier conditions and prolonged periods of drought.
The study’s authors believe the study gives insight into how the current melting of the ice sheets in Greenland may affect global climate systems.
Dr Rush added: “We know that the AMOC is currently slowing down and, although it is still debated, some forecasts indicate that it could close completely. However, by looking at past events we can learn more about the causes of these changes and their likelihood. We have shown that the rapid retreat of the ice sheet, which may occur in Greenland depending on the trajectory of future fossil fuel emissions, “can cause a variety of important climate effects that would have very worrying consequences.”
The findings are published in the journal Quaternary Science Advances.
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