Less sea ice — no more driftwood in Iceland? | Polarjournal
Already, much less driftwood is reaching Svalbard, Iceland and Greenland with the sea ice across the Arctic Ocean from Siberia. Instead, more and more plastic is washing up on the beaches. Photo: Julia Hager

Driftwood was and still is the most important resource for (sub) Arctic settlements. Without the driftwood that piled up on Iceland’s beaches, the island’s permanent settlement, which began with the Vikings in the 9th century, would not have been possible. For a long time, the washed up logs served the settlers for the construction of buildings and ships, for which the native trees were much too small and sparse. According to a new study that was published in the journal Global and Planetary Change, much of the driftwood in Iceland comes from Siberia on the other side of the Arctic Ocean. Even today, driftwood has a high cultural value for Icelanders. Climate change, however, could stop driftwood supply to Iceland, the study found.

Sea ice is virtually the only means of transport for driftwood in the Arctic. Only with the help of this “conveyor belt”, trees – logged or naturally fallen in Russia’s Central Siberian region – could travel thousands of kilometers across the Arctic Ocean to islands and coasts on the other side. It is because wood only floats for about ten months and begins to sink as soon as it is waterlogged. In the Arctic, however, it freezes in the sea ice and thus cannot soak up water. Perhaps only after a few years it is released again with the melting of the sea ice and can be washed up on coasts as driftwood.

For the settlement and expansion of the Norse, driftwood on Iceland’s coasts was crucial and is an important part of Icelandic history. “It’s a cultural thing,” says Ólafur Eggertsson, a scientist with the Icelandic Forest Service and co-author of the study. “If it hadn’t been for the driftwood, people would have just not survived in Iceland.”

Origin of the Icelandic driftwood. The red circle marks the sampling location for driftwood in northeast Iceland. The presumed source areas of Arctic driftwood are in the Eurasian boreal forest zone (colored circles), near the largest river systems. The colored dots show the locations of the species-specific reference chronologies for tree ring width. Map: Kolář et al. 2022

However, the supply of driftwood to Iceland, as well as Greenland and Svalbard, could come to a halt in the next few decades. According to the study, an abrupt decline in driftwood began as early as the 1980s, and simulations of sea ice loss show that no more driftwood will reach Iceland by 2060.

“The take-home message [of] the paper is expected and has a value of providing a very clear signpost of what sea ice melt means for this material to be transported in the Arctic,” said Marc Macias-Fauria, a University of Oxford ecologist who focuses on cold environments and was not involved in the study.

The effect of sea ice on driftwood occurrence in Iceland. (a) September sea ice extent calculated as 20-year averages from 1860 to 1979, (b-c) satellite observations for 1979 and 2019, (d) model simulations based on a subset of eight global climate models as 10-year averages from 2020 to 2099. Graphic: Kolář et al. 2022

The research team also collected 289 samples of driftwood along Iceland’s northeast coast and identified the tree species under the microscope: pine, larch and spruce. They compared the tree rings to Eurasian tree ring records and found that 73 percent of the samples matched trees from Siberia.

The tree rings also revealed the decline in driftwood transport to Iceland in recent decades. Eighty percent of the samples had tree rings dated between 1922 and 1976, while 14 trees stopped growing in the 1980s. Only three samples were from the period after. The research team attributes this to disappearing sea ice.

Analysis also showed that 83 percent of the samples came from trees that had been cut down. The remaining 17 percent still had parts of the roots intact, indicating that they likely fell naturally before being transported to the Arctic Ocean via Siberian rivers.

On Svalbard, too, most of the driftwood consists of felled trees. Photo: Julia Hager

For Icelanders, driftwood is not as important a source of wood as it once was, but they still use it for buildings, sculptures, to restore old churches and as a source of income, Eggertsson said.

With the loss of the driftwood, a significant part of Iceland’s history and culture would thus be lost.

Julia Hager, PolarJournal

Link to the study: Tomáš Kolář, Michal Rybníček, Ólafur Eggertsson et al. Predicted sea-ice loss will terminate Iceland’s driftwood supply by 2060 CE. Global and Planetary Change, Volume 213, 2022, 103834, https://doi.org/10.1016/j.gloplacha.2022.103834

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