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This dataset documents the location and characteristics of 185 exotic tundra boulders found on the North Slope of Alaska, spanning observations from 1826 to 2025. These boulders—scattered across coastal tundra, estuarine margins, and barrier islands—represent a persistent but enigmatic feature of the Arctic landscape. Their lithologies, which include granite, quartzite, diabase, dolomite, chert, and gneiss, are exotic to the region and are widely interpreted to be ice-rafted debris deposited during Pleistocene highstands of the Arctic Ocean. Spatial and lithologic patterns suggest an origin in the Canadian Arctic Archipelago and Mackenzie River basin, transported westward by sea ice or icebergs during glacial periods. The dataset integrates georeferenced boulder locations from early exploration accounts (e.g., Leffingwell 1919; Stefansson 1910, Franklin and Richardson 1828), mid-century field surveys (MacCarthy 1958), geologic interpretations of offshore facies and provenance (Rodeick 1979) and USGS (U.S. Geological Survey) engineering geological maps (1980s), and modern field observations from the 2000s–2020s. Boulder characteristics—such as lithology, surface striations, and faceting—are included where available. These observations contribute to understanding of likely saline permafrost distribution, Arctic coastal dynamics, sea-level history, and the paleogeography of iceberg and sea-ice transport. They also provide a rare terrestrial window into ice-rafted sedimentation processes typically studied in marine environments. All data are curated in a comma separated spreadsheet with associated metadata to support future geomorphological, paleoclimatic, and sea-level modeling studies. The complete list of references is provided below: Barnes, P.W., 1982. Marine Ice-Pushed Boulder Ridge, Beaufort Sea, Alaska. ARCTIC 35, 312–316. https://doi.org/10.14430/arctic2330 Brigham, O.K., 1985. Marine stratigraphy and aaino-acid geochronology of the Gublk Fomatlon, western Arctic Coastal Plain, Alaska. USGS Open File Report 381. Dease, P.W., Simpson, T., 1838. An Account of the Recent Arctic Discoveries by Messrs. Dease and T. Simpson. The Journal of the Royal Geographical Society of London 8, 213–225. Franklin, J., Richardson, J., 1828. Narrative of a Second Expedition to the Shores of the Polar Sea, in the Years 1825, 1826, and 1827. Carey, Lea and Carey. Gibbs, A.E., Richmond, B.M., 2009. Oblique aerial photography of the Arctic coast of Alaska, Nulavik to Demarcation Point, August 7-10, 2006. US Geological Survey. Hopkins, D.M., Hartz, R.W., 1978. Coastal morphology, coastal erosion, and barrier islands of the Beaufort Sea, Alaska. US Geological Survey,. Jorgenson, M.T., 2011. Coastal region of northern Alaska, Guidebook to permafrost and related features (No.GB 10). Alaska Division of Geological and Geophysical Surveys. https://doi.org/10.14509/22762 McCarthy, G.R., 1958. Glacial Boulders on the Arctic Coast of Alaska. ARCTIC 11, 70–85. https://doi.org/10.14430/arctic3734 Naidu, A., Mowatt, T., 1992. Origin of gravels from the southern coast and continental shelf of the Beaufort Sea, Arctic Alaska, in: 1992 International Conference on Arctic Margins Proceedings Programs with Abstracts. pp. 351–356. O’Sullivan, J.B., 1961. Quaternary geology of the Arctic Coastal Plain, northern Alaska: Ames, Iowa, Iowa State University of Science and Technology, Ph.D. dissertation, 191 p., illust., maps. Iowa State University. Rawlinson, S.E., 1993. Surficial geology and morphology of the Alaskan central Arctic Coastal Plain (No. RI 93-1). Alaska Division of Geological and Geophysical Surveys. https://doi.org/10.14509/2484 Reimnitz, E., Ross, R., 1979. Lag deposits of boulders in Stefansson Sound, Beaufort Sea, Alaska (No.79–1205), Open-File Report. U.S. Geological Survey,. https://doi.org/10.3133/ofr791205 Rodeick, C.A., 1979. The origin, distribution, and depositional history of gravel deposits on the Beaufort Sea Continental Shelf, Alaska (No. 79–234), Open-File Report. U.S. Geological Survey,. https://doi.org/10.3133/ofr79234 Schrader, F.C., Peters, W.J., 1904. A reconnaissance in northern Alaska across the Rocky Mountains, along Koyukuk, John, Anaktuvuk, and Colville Rivers, and the Arctic coast to Cape Lisburne, in 1901, with notes (USGS Numbered Series No. 20), Professional Paper. U.S. Geological Survey, Washington, D.C. https://doi.org/10.3133/pp20 Simpson, 1855. Observations on the western Esquimaux and the country they inhabit?: from notes taken during two years at Point Barrow | CiNii Research [WWW Document]. URL https://cir.nii.ac.jp/crid/1130000795332231552 (accessed 6.10.23). Smith, P.S., Mertie, J.B., 1930. Geology and mineral resources of northwestern Alaska. USGS Report 1. Stefansson, V., 1910. Notes from the Arctic. Am. Geogr. SOC. Bull 42, 460–1. Williams, J.R., 1983. Engineering-geologic maps of northern Alaska, Wainwright quadrangle (No. 83–457), Open-File Report. U.S. Geological Survey. https://doi.org/10.3133/ofr83458 Williams, J.R., Carter, L.D., 1984. Engineering-geologic maps of northern Alaska, Barrow quadrangle (No.84–124), Open-File Report. U.S. Geological Survey. https://doi.org/10.3133/ofr84126 Williams, R.J., 1983. Engineering-geologic maps of northern Alaska, Meade River quadrangle (No. 83–294), Open-File Report. U.S. Geological Survey. https://doi.org/10.3133/ofr83325 Wolf, S.C., Reimnitz, E., Barnes, P.W., 1985. Pleistocene and Holocene seismic stratigraphy between the Canning River and Prudhoe Bay, Beaufort Sea, Alaska. US Geological Survey,. de Koven Leffingwell, E., 1908. Flaxman Island, a Glacial Remnant. The Journal of Geology 16, 56–63. https://doi.org/10.1086/621490 de Koven Leffingwell, E., 1919. The Canning river region, northern Alaska (No. 109). US Government Printing Office. 

Arctic shorelines are vulnerable to climate change impacts as sea level rises, permafrost thaws, storms intensify, and sea ice thins. Seventy-five years of aerial and satellite observations have established coastal erosion as an increasing Arctic hazard. However, other hazards at play—for instance, the cumulative impact that sea-level rise and permafrost thaw subsidence will have on permafrost shorelines—have received less attention, preventing assessments of these processes’ impacts compared to and combined with coastal erosion. Alaska’s Arctic Coastal Plain (ACP) is ideal for such assessments because of the high-density observations of topography, coastal retreat rates, and permafrost characteristics, and importance to Indigenous communities and oilfield infrastructure. Here, we produce 21st-century projections of Arctic shoreline position that include erosion, permafrost subsidence, and sea-level rise. Focusing on the ACP, we merge 5 m topography, satellite-derived coastal lake depth estimates, and empirical assessments of land subsidence due to permafrost thaw with projections of coastal erosion and sea-level rise for medium and high emissions scenarios from the Intergovernmental Panel on Climate Change’s AR6 Report. We find that by 2100, erosion and inundation will together transform the ACP, leading to 6-8x more land loss than coastal erosion alone and disturbing 8-11x more organic carbon. Without mitigating measures, by 2100, coastal change could damage 40 to 65% of infrastructure in present-day ACP coastal villages and 10 to 20% of oilfield infrastructure. Our findings highlight the risks that compounding climate hazards pose to coastal communities and underscore the need for adaptive planning for Arctic coastlines in the 21st century. 

Abstract Sea-level rise submerges terrestrial permafrost in the Arctic, turning it into subsea permafrost. Subsea permafrost underlies ~ 1.8 million km²of Arctic continental shelf, with thicknesses in places exceeding 700 m. Sea-level variations over glacial-interglacial cycles control subsea permafrost distribution and thickness, yet no permafrost model has accounted for glacial isostatic adjustment (GIA), which deviates local sea level from the global mean due to changes in ice and ocean loading. Here we incorporate GIA into a pan-Arctic model of subsea permafrost over the last 400,000 years. Including GIA significantly reduces present-day subsea permafrost thickness, chiefly because of hydro-isostatic effects as well as deformation related to Northern Hemisphere ice sheets. Additionally, we extend the simulation 1000 years into the future for emissions scenarios outlined in the Intergovernmental Panel on Climate Change’s sixth assessment report. We find that subsea permafrost is preserved under a low emissions scenario but mostly disappears under a high emissions scenario. 

Polar temperatures during the Last Interglacial [LIG; ~129 to 116 thousand years (ka)] were warmer than today, making this time period an important testing ground to better understand how ice sheets respond to warming. However, it remains debated how much and when the Antarctic and Greenland ice sheets changed during this period. Here, we present a combination of new and existing absolutely dated LIG sea-level observations from Britain, France, and Denmark. Because of glacial isostatic adjustment (GIA), the LIG Greenland ice melt contribution to sea-level change in this region is small, which allows us to constrain Antarctic ice change. We find that the Antarctic contribution to LIG global mean sea level peaked early in the interglacial (before 126 ka), with a maximum contribution of 5.7 m (50th percentile, 3.6 to 8.7 m central 68% probability) before declining. Our results support an asynchronous melt history over the LIG, with an early Antarctic contribution followed by later Greenland Ice Sheet mass loss. 

During the last interglacial (LIG) period, global mean sea level (GMSL) was higher than at present, likely driven by greater high-latitude insolation. Past sea-level estimates require elevation measurements and age determination of marine sediments that formed at or near sea level, and those elevations must be corrected for glacial isostatic adjustment (GIA). However, this GIA correction is subject to uncertainties in the GIA model inputs, namely, Earth’s rheology and past ice history, which reduces precision and accuracy in estimates of past GMSL. To better constrain the GIA process, we compare our data and existing LIG sea-level data across the Bahamian archipelago with a suite of 576 GIA model predictions. We calculated weights for each GIA model based on how well the model fits spatial trends in the regional sea-level data and then used the weighted GIA corrections to revise estimates of GMSL during the LIG. During the LIG, we find a 95% probability that global sea level peaked at least 1.2 m higher than today, and it is very unlikely (5% probability) to have exceeded 5.3 m. Estimates increase by up to 30% (decrease by up to 20%) for portions of melt that originate from the Greenland ice sheet (West Antarctic ice sheet). Altogether, this work suggests that LIG GMSL may be lower than previously assumed.