Geoscientist Georgia Hole utilized tree rings to backtrack the courses of driftwood, when frozen in sea ice, as it made its method through theArctic “Some of these beaches are really full of driftwood—driftwood as far as the eye can see. And when you remember that these areas we were studying had no forest, completely treeless, it gives you that sense of scale.” -GH Credit: Georgia Hole
Fallen trees survived in sea ice show sped up ice loss in the last 30 years.
A brand-new research study rebuilds the course of frozen trees as they made their method throughout the Arctic Ocean over 500 years, providing researchers a distinct check out modifications in sea ice and currents over the last half millennium.
By dating and tracing pieces of driftwood on beaches in Svalbard, Norway’s island chain in the Arctic Circle, researchers have actually figured out where these fallen trees drifted. Retracing the driftwood’s journey let the scientists rebuild, for the very first time, both the level of sea ice over time and the currents that moved the driftwood-laden ice.
Borne by rivers to the ocean, fallen trees from the north’s extensive boreal forests can be frozen in sea ice and float far, however the brand-new research study showsfewer trees are making the long journey as the sea ice that brings them diminishes away.
The brand-new research study discovered an unique drop in brand-new driftwood arrivals over the last 30 years, showing the high decrease in sea ice protection in a warming Arctic and supplies a higher-resolution photo of past Arctic Ocean conditions than other techniques permit. The research study is released in the Journal of Geophysical Research: Oceans, which releases research study that advances our understanding of the ocean and its procedures.
A piece of larix (larch) driftwood gathered from Phipps øya, The Seven Islands, matched to an origin along the Lena River in Russia in the 1700 s. The piece was sanded, exposing the maintained rings. Credit: Georgia Hole
Sea ice is delicate to environment modification and is a fundamental part of Arctic environments, so comprehending how ice, ocean temperature levels, and currents have actually differed together with time is essential for anticipating coming modifications in theArctic But doing so can be evasive: Ice melts, after all. The earliest sea ice is just about 4 years of ages (and getting more youthful), so researchers require to rely on other records.
“This is the first time driftwood has been used to look at large-scale changes in Arctic sea ice dynamics and circulation patterns,” stated geoscientist Georgia Hole at the University of Oxford, who led the research study.
“They’re taking the analysis one step further to connect changes in driftwood to changes in sea ice, and that’s where we want to go. It’s really exciting,” stated Hans Linderholm, a paleoclimatologist at the University of Gothenburg in Sweden who was not associated with the research study.
Important ice
The Arctic Ocean gathers trees that naturally fall under high-latitude rivers in North America andEurasia When it was cold enough, a few of the trees were frozen into the sea ice. The ice then drifted throughout the ocean, swept along by ocean currents and winds, up until beaching on Svalbard’s coasts. There they sat, some for centuries, up until scientists like Hole and Linderholm occurred.
A thin area of a really unspoiled piece of Picea (spruce) driftwood. The tree’s physiological information enabled Hole to determine and trace it. Credit: Georgia Hole
Researchers have actually utilized driftwood for climate-change research studies prior to, however the brand-new research study is the very first to check how helpful Arctic driftwood is for peering into previous currents and ice protection. To inspect their work, the research study straight compared driftwood-inferred sea ice protection to the observational record of sea ice.
“This is a fantastic resource to say something about ocean currents and sea ice conditions,” statedLinderholm “I believe they do have a case for matching [tree] provenance modifications to modifications in sea ice conditions, which is what we’re searching for: to have sea ice details prior to observations.”
Tracing trees
In the summer season of 2016 and 2018, Hole and her partners combed a number of beaches in northern Svalbard for driftwood. Back in the laboratory, they evaluated the tree rings to identify what sort of tree it was and compared the tree ring patterns of each driftwood piece to a database of determined rings from trees throughout the boreal forests. Hole might then trace trees to private nations, watersheds, and even rivers and see how driftwood sources differed with time.
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. More current sea ice information originated from aircraft and satellite images. Finally, she compared driftwood-tracking information with sea ice conditions and currents to see how well they associated.
Her information exposed a sluggish and stable northward migration of the lowest-latitude sea ice, showing warming, in addition to swings in driftwood arrivals in between North America and Eurasia.
“We also saw an increase in variability in the driftwood record from 1700 to 1850, which we interpret as increased variability in sea ice,” statedHole Colder conditions tend to have more sea ice, so previously driftwood showed a broader variety of sources. As the Arctic heated up and sea ice melted, less driftwood might make the long journey.
The special approach supplies nuanced insights that other strategies can’t use, and this research study is simply the start– up until the Arctic loses its sea ice entirely, that is.
“It’s such a fragile system,” Hole stated. “If the sea ice does decline as predicted, then this will kind of be a dying 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 Ing ólfsson and Marc Macias-Fauria, 15 September 2021, Journal of Geophysical Research: Oceans
DOI: 10.1029/2021 JC017563
Authors:
- Georgia M. Hole (matching 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, Reykjav ík, Iceland; Department of Arctic Geology, The University Centre in Svalbard (UNIS), Longyearbyen, Norway
- Anders Schomacker, Department of Geosciences, The Arctic University of Norway, Troms ø, Norway
- Ölafur Ing ólsson, Department of Arctic Geology, The University Centre in Svalbard (UNIS), Longyearbyen, Norway; Faculty of Earth Sciences, University of Iceland, Reykjav ík, Iceland
