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The data publication contains supplementary data to the article "Supplementary Dataset to: The catastrophic thermokarst lake drainage events of 2018 in northwestern Alaska: Fast-forward into the future" This data publication includes four datasets: 1. Lake change datasets for 1999-2014 and 2017-2018 based on Landsat and Sentinel-1 data as Polygon Shapefiles 2. Lake change datasets for 2017 and 2018 based on high-temporal resolution PlanetScope imagery as Polygon Shapefiles and csv. 3. Lake ice simulations for the study area for 1980-2018. 4. Study sites in two versions: a) including seawater and b) clipped to land area. Files are Polygon Shapefiles. The datasets cover the land area of the Baldwin Peninsula and northern Seward Peninsula in north-western Alaska. The datasets are (#1) remote sensing based observations and (#3) modelled data. Methods are described in detail in the original manuscript (open access). Dataset #4 is the extent of the study site in two versions, a) full extent including seawater and b) land only including lakes. The land boundary was clipped with the “Global Self-consistent, Hierarchical, High-resolution Geography Database” (GSHHG; Wessel and Smith, 1996) dataset in scale “h”. The datasets cover different temporal periods and have a different temporal resolution. Data were collected to measure the extent of a rapid and widespread thermokarst lake drainage event in northwestern Alaska in 2018 and to compare the affected number of lakes and area to previous periods. Lake-ice model data were calculated to simulate lake-ice conditions since 1980 and to put the lake-ice and weather conditions in 2017/2018 into context.

If not reported, water-filled pore space (WFPS) was calculated as follows: WFPS (%) = VWC/(1-BD/PD)*100, where VWC is the volumetric water content, BD is the bulk density, and PD is the particle density. If BD was not reported, BD was estimated from the SOM content using functions developed for Arctic soils (Hossain et al, 2015) as follows: 0.075+1.301*EXP(-0.06*SOM) for mineral soils, and 0.043*0+4.258*EXP(-0.047*SOM) for organic soils. If not reported, SOM via loss on ignition was derived from the soil carbon content as follows: SOM (%) = C content*2. If the resulting SOM value was >100%, SOM (%) = C content*1.724. PD can be derived as follows (Okruszko, 1971): PD = 0.011*(100-SOM)+1.451 (see references Okruszko, 1971 and Hossain et al, 2015). The term ”topsoil” depends on the exact depths the soil characteristics are reported in the individual publications, but generally the soil layer of 0–10cm was used. Column ”SOC” includes mostly total soil C content (reported in the majority of studies), and on some occasions total organic C. This dataset is a synthesis of published nitrous oxide (N2O) fluxes from permafrost-affected soils in Arctic, Antarctic, and Alpine permafrost regions. The data includes mean N2O flux rates measured under field (in situ) conditions and in intact plant-soil systems (mesocosms) under near-field conditions. The dataset further includes explanatory environmental parameters such as meteorological data, soil physical-chemical properties, as well as site and experimental information. Data has been synthesized from published studies (see 'Further details'), and in some cases the authors of published studies have been contacted for additional site-level information. The dataset includes studies published until 2019. We encourage linking additional N2O flux data from unpublished and future studies with similar metadata structure to this dataset, to produce a comprehensive, findable database for N2O fluxes from permafrost regions.

Narrowing uncertainties about carbon cycling is important in the Arctic where rapid environmental changes contribute to enhanced mobilization of carbon. Here we quantify soil organic carbon (SOC) contents of permafrost soils along the Yukon Coastal Plain and determine the annual fluxes from erosion. Different terrain units are assessed based on surficial geology, morphology, and ground ice conditions. To account for the volume of wedge ice and massive ice in a unit, sample SOC contents are reduced by 19% and sediment contents by 16%. The SOC content in a 1 m**2 column of soil varies according to the height of the bluff, ranging from 30 to 662 kg, with a mean value of 183 kg. Forty-four per cent of the SOC is within the top 1 m of soil and values vary based on surficial materials, ranging from 30 to 53 kg C/m**3, with a mean of 41 kg. Eighty per cent of the shoreline is erosive with a mean annual rate of change is 0.7 m/a. This results in a SOC flux per meter of shoreline of 131 kg C/m/a, and a total flux for the entire Yukon coast of 35.5 10**6 kg C/a (0.036 Tg C/a). The mean flux of sediment per meter of shoreline is 5.3 10**3 kg/m/a, with a total flux of 1,832.0 10**6 kg/a (1.832 Tg/a). Sedimentation rates indicate that approximately 13% of the eroded carbon is sequestered in nearshore sediments, where the overwhelming majority of organic carbon is of terrestrial origin. Supplement to: Couture, Nicole; Irrgang, Anna Maria; Pollard, Wayne H; Lantuit, Hugues; Fritz, Michael (2018): Coastal Erosion of Permafrost Soils Along the Yukon Coastal Plain and Fluxes of Organic Carbon to the Canadian Beaufort Sea. Journal of Geophysical Research: Biogeosciences