Geoscientist Georgia Hole used tree rings to backtrack the paths of driftwood, when frozen in sea ice, as it made its method through the Arctic. “Some of these beaches are really complete of driftwood– driftwood as far as the eye can see.
Fallen trees kept afloat in sea ice reflect accelerated ice loss in the last 30 years.
A new research study rebuilds the course of frozen trees as they made their way across the Arctic Ocean over 500 years, offering researchers an unique look into modifications in sea ice and currents over the last half millennium.
By dating and tracing pieces of driftwood on beaches in Svalbard, Norways island chain in the Arctic Circle, scientists have figured out where these fallen trees floated. Retracing the driftwoods journey let the scientists reconstruct, for the very first time, both the level of sea ice over time and the currents that propelled the driftwood-laden ice.
Borne by rivers to the ocean, fallen trees from the norths expansive boreal forests can be frozen in sea ice and float far, but the brand-new research showsfewer trees are making the long journey as the sea ice that brings them diminishes away.
The brand-new research study found a distinct drop in new driftwood arrivals over the last 30 years, reflecting the steep decline in sea ice protection in a warming Arctic and provides a higher-resolution picture of past Arctic Ocean conditions than other approaches enable. The research study is released in the Journal of Geophysical Research: Oceans, which releases research that advances our understanding of the ocean and its procedures.
A slice of larix (larch) driftwood collected from Phippsøya, The Seven Islands, matched to an origin along the Lena River in Russia in the 1700s. The piece was sanded, exposing the maintained rings. Credit: Georgia Hole
Sea ice is sensitive to environment change and is a crucial part of Arctic environments, so comprehending how ice, ocean temperature levels, and currents have differed together in time is needed for predicting coming changes in the Arctic. But doing so can be evasive: Ice melts, after all. The oldest sea ice is just about 4 years old (and getting younger), so researchers require to turn to other records.
” This is the very first time driftwood has been utilized to take a look at large-scale modifications in Arctic sea ice characteristics and flow patterns,” stated geoscientist Georgia Hole at the University of Oxford, who led the study.
” Theyre taking the analysis one step further to link changes in driftwood to modifications in sea ice, and thats where we wish to go. Its really interesting,” said Hans Linderholm, a paleoclimatologist at the University of Gothenburg in Sweden who was not included in the research.
Crucial ice
When it was cold enough, some of the trees were frozen into the sea ice. The ice then floated throughout the ocean, swept along by ocean currents and winds, till beaching on Svalbards coasts.
A thin area of a really unspoiled piece of Picea (spruce) driftwood. The trees anatomical information enabled Hole to recognize and trace it. Credit: Georgia Hole
Scientists have utilized driftwood for climate-change research studies before, but the brand-new research study is the very first to test how useful Arctic driftwood is for peering into past currents and ice protection. To examine their work, the research study directly compared driftwood-inferred sea ice coverage to the observational record of sea ice.
” This is a great resource to say something about ocean currents and sea ice conditions,” said Linderholm.
Tracing trees
In the summer months of 2016 and 2018, Hole and her partners combed a number of beaches in northern Svalbard for driftwood. Back in the lab, they analyzed the tree rings to identify what kind of tree it compared the tree and was ring patterns of each driftwood piece to a database of measured rings from trees throughout the boreal forests. Hole might then trace trees to specific countries, watersheds, and even rivers and see how driftwood sources varied over time.
Hole paired her driftwood data with early sea ice observations, from 1600 to 1850, thanks to records from Icelandic fishers, seal hunters, and passing ships. More current sea ice information came from airplane and satellite imagery. She compared driftwood-tracking data with sea ice conditions and currents to see how well they correlated.
Her data revealed a consistent and sluggish northward migration of the lowest-latitude sea ice, showing warming, together with swings in driftwood arrivals in between North America and Eurasia.
” We likewise saw an increase in irregularity in the driftwood record from 1700 to 1850, which we analyze as increased irregularity in sea ice,” stated Hole. Chillier conditions tend to have more sea ice, so previously driftwood showed a broader range of sources. As the Arctic warmed up and sea ice melted, less driftwood might make the long journey.
The unique method provides nuanced insights that other methods cant use, and this research study is just the start– up until the Arctic loses its sea ice completely, that is.
” Its such a vulnerable system,” Hole said. “If the sea ice does decline as anticipated, then this will sort of be a passing away field.”
Reference: “A Driftwood-Based Record of Arctic Sea Ice During the Last 500 Years From Northern Svalbard Reveals Sea Ice Dynamics in the Arctic Ocean and Arctic Peripheral Seas” by Georgia M. Hole, Thomas Rawson, Wesley R. Farnsworth, Anders Schomacker, Ólafur Ingólfsson and Marc Macias-Fauria, 15 September 2021, Journal of Geophysical Research: Oceans.DOI: 10.1029/ 2021JC017563.
Authors:.
Geoscientist Georgia Hole utilized tree rings to retrace the courses of driftwood, as soon as frozen in sea ice, as it made its way through the Arctic. Sea ice is sensitive to environment modification and is an essential part of Arctic environments, so comprehending how ice, ocean temperature levels, and currents have actually varied together over time is essential for predicting coming modifications in the Arctic. Hole paired her driftwood information with early sea ice observations, from 1600 to 1850, thanks to records from Icelandic fishers, seal hunters, and passing ships.” We also saw a boost in irregularity in the driftwood record from 1700 to 1850, which we interpret as increased irregularity in sea ice,” stated Hole. As the Arctic warmed up and sea ice melted, less driftwood could make the long journey.
Georgia M. Hole (corresponding author), Marc Macias-Fauria, Biogeosciences Research Group, School of Geography and the Environment, University of Oxford, Oxford, UK.
Thomas Rawson, Department of Zoology, Mathematical Ecology Research Group, University of Oxford, Oxford, UK.
Wesley R. Farnsworth, Nordic Volcanological Center, University of Iceland, Reykjavík, Iceland; Department of Arctic Geology, The University Centre in Svalbard (UNIS), Longyearbyen, Norway.
Anders Schomacker, Department of Geosciences, The Arctic University of Norway, Tromsø, Norway.
Ölafur Ingólsson, Department of Arctic Geology, The University Centre in Svalbard (UNIS), Longyearbyen, Norway; Faculty of Earth Sciences, University of Iceland, Reykjavík, Iceland.