TORONTO — Driftwood found off the coast of northern Svalbard that was once frozen in sea ice provides insight into changes in ice and Arctic Ocean currents over the past 500 years, according to a new study that traces their migration from boreal forests to the north. traces the journey. For beaches in the archipelago of Norway.

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paper, Published in the Journal of Geophysical Research: Oceans, found that less driftwood has made its way to Svalbard over the past three decades, a change that underscores how much sea ice – a vital part of the Arctic ecosystem – is melting.

Driftwood comes from dying trees – some hundreds of years ago – that fall into large, high-latitude rivers in North America and Eurasia, which then flow into the Arctic Ocean. Wood can become trapped in the sea ice that forms, which allows it to travel with Arctic currents without sinking, making it an important mediator for measuring the area of ​​the ocean covered by sea ice.

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The oldest Arctic sea ice is only about four years old and is getting younger, making it challenging for scientists to track and better understand how ice, ocean temperatures and currents have changed over time and how it is in the future. What does it indicate.

The study, by a team of scientists from the UK, Iceland and Norway, measured tree ring widths from driftwood specimens and compared them with tree ring widths from trees in boreal forests to determine what driftwood originally was. came from the country or watershed. And what kind of tree was that? The scientists were also able to detect driftwood in some specific rivers. This allowed the researchers to estimate the likely path it would take across the ocean.

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The results were then compared with observations of sea ice from Icelandic fishermen, seal hunters and passing ships dating back to the 1600s and more recent data from sources, including satellite images, to see if the results are correlated.

The study found that older driftwoods from 1700 to 1850 came from a wide range of sources—meaning there was more sea ice carrying fallen trees from a variety of locations. As warmer temperatures melt Arctic sea ice, less driftwood can be carried over long distances in frozen ice.

“Driftwood deposits on Arctic shorelines are a unique and currently under-utilized resource for reconstructing sea ice transport within the large-scale Arctic Ocean circulation in the Holocene,” the authors write in the study.

While using driftwood to study climate change is nothing new, this is the first study to examine whether it can be used to examine past currents and snow coverage.

“It’s such a fragile system,” the study’s lead author, University of Oxford geophysicist Georgia Hole, said in a statement. “If sea ice declines as predicted, it will be a dying zone.”