The Arctic is changing rapidly. Research published this month in Remote Sensing of Environment unveiled a new dataset of 40 years of coastlines shifting across the Arctic.
The dataset, created by researchers from the University of Turku and the University of Helsinki, tracks coastal erosion and accretion in the Arctic from 1984 to 2023 using Landsat imagery. Eight percent of the sampled locations are experiencing rapid change, defined as coastal erosion or accretion of more than ten meters per year. Compared to other similar datasets, the strength of this new product is that it allows users to identify coastal change hotspots at global, regional, and local scales. It also has circumpolar coverage and covers a much longer time period than other datasets.
Arctic coastlines are some of the most rapidly changing coastlines on Earth. The combined impact of warming, rising sea levels, glacial retreat, and permafrost thaw has destabilized many coastlines, making them vulnerable to erosion. Tracking how and where the coastlines are changing is critical for local populations, whose settlements, transportation, and economies are impacted by changing land conditions.
Researchers used three distinct calibration sites to develop and then validate the procedure: Tanafjorden in Norway’s Barents Sea, Ny-Ålesund in Svalbard, and the Canadian Yukon coast. For each calibration site, they used high-resolution aerial photos and satellite imagery to manually classify each pixel as land, sea, and summer ice. Then, they used imagery from Landsats 5, 7, and 8 to detect land, sea and ice, and compared the results to the manually-labeled data, before applying the analysis all over the Arctic coast. They confined their study to looking at Arctic coastlines in summertime to limit the impact of sea ice.
By analyzing data from 1984-2023, Nylén et al, 2025 was able to see which coastlines were eroding and which were growing. Erosion hotspots include the northern coast of Alaska, Yukon, the Northwest Territories, Hudson Bay, Yamalo-Nenets, Krasnoyarsk, and Sakha. The most stable coastlines were the rocky coasts of Newfoundland, western Greenland, Norway, Iceland, and Russia’s Novaya Zemlya. Most area of coastal accretion were in areas of postglacial rebound, where the land mass rises like an expanding sponge in the absence of the huge weight of the glacier. In this study, the hotspots of coastal accretion were in northeastern Canada, Greenland, Iceland, Norway, Svalbard, and Novaya Zemlya.
Researchers evaluated coastal change at local and regional scales. For example, Point Hope in the Alaskan Chukchi Sea has significant local differences in coastal change. Close to the airport, in the northwest tip of the Point Hope, had an average erosion rate of 1 meter per year. On the southern coast close to a town, the average accretion rate was over 1 meter per year. These local differences are essential for land managers to make informed decisions about the future of their communities. Landsat, with its long data record and global coverage, is an invaluable tool to track rapidly shifting coastlines worldwide and help predict what may come next.
