A sediment core from Svalbard has revealed a sudden influx of warm water in the Arctic in 1907, which is evidence of a process that is spurring ice loss
24 November 2021
Salty Atlantic waters may have been seeping into the Arctic since the early 20th century, several decades earlier than previously believed. The Arctic is warming faster than any part of the world and the increasing influence of water from the Atlantic Ocean, which is warmer and saltier than average for the Arctic Ocean, is likely leading to further ice loss.
This effect is known as “Atlantification”, says Tesi Tommaso at the Italian National Research Council Institute of Polar Sciences. But it is hard to quantify as we only have 20 years of confirmed data about the interaction between these waters, he adds.
He and his colleagues studied the Fram Strait in the Arctic Ocean between Greenland and the Norwegian archipelago Svalbard. They used a 112-centimetre sediment core that they collected from one of Svalbard’s inlets to reconstruct the history of the strait.
“The rock is in the ocean,” says Tommaso. “What we see is a reflection of the water’s properties.”
The layers of the core correspond to sediments laid down over the past 800 years, which hold clues to the time they were deposited. “Every centimetre gave us climate information for about four to five years,” says Tommaso.
The team found that for the earliest 700 years or so, nothing changed in the composition of organic matter in the sediment. But in samples corresponding to the year 1907, they saw a sudden change in the oxygen isotopes in the organic matter. “This change suggests the waters became a lot warmer and saltier,” says Tommaso.
The team is unsure what caused this dramatic shift in temperature. “It could be a natural event that propagated from the subpolar regions to the gate of the Arctic Ocean,” Tommaso says.
More data and modelling are needed to gain a clearer picture of what caused this sudden change, he says.
“This early Atlantification is important as it will have pre-conditioned the Arctic to be susceptible to the more rapid change seen today,” says Yueng-Djern Lenn at Bangor University in the UK, who was not involved in the work.
Understanding the history of this effect can tell us about how the ecosystem may respond in the future, says Marie Porter at the Scottish Association for Marine Sciences, who was also not involved. “The process of Atlantification continues across the Atlantic-Arctic under post-industrialisation climate change.”
Journal reference: Science Advances, DOI: 10.1126/sciadv.abj2946
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