Description: The object of research is the Holocene massive ice veins on the Eastern coast of the Daurkin Peninsula, the easternmost part of the Chukotka. Peat bogs with ice veins occur on the surface of marine terraces (near Uelen and Lorino settlements) and on flood plain of the Koolen' Lake; the thickness of peat varies from 0.7 to 2.5 m. Radiocarbon dating of the peat enclosing the investigated ice veins near Uelen and Lorino indicated that the beginning of peat accumulation began at the end of Late Pleistocene - early Holocene, about 11 cal ka BP. On the flood plain of the Koolen' Lake peat bogs began to accumulate in the middle Holocene, i.e. around 6 cal ka BP. At the initial stage of peat bogs formation the rate of peat accumulation was high and could reach 1 cm/10 years. Ice veins occur at a depth of 0.5-1 m, and their lower parts are located in the underlying peat sandy loams and loams. In the upper levels of the peat bogs, narrow present-day ice veins are found, which are sometimes embedded in the upper parts of Holocene veins. A clear sign of syngenetic growth of veins is the upward bending of the layers of the host peat at the lateral contacts with the veins. The main source of water for the formation of ice veins is snow, as evidenced by the ratio of stable isotopes of oxygen and hydrogen and the values of deuterium excesses in the ice. A slight admixture of saline water (probably from a seasonally thawed layer) was noted in the veins near the Lorino settlement. Reconstructions of winter air paleotemperatures, performed on the basis of data of isotope-oxygen composition of ice from the veins, did show that at the period between 11 and 6 cal Ka BP, the mean winter air temperature on the Daurkin Peninsula was by 2-5 °C lower than today, but the air temperature of the coldest month (January or February) was still lower (by 4-8 °C) than today. The noticeable trend of increase of stable isotope values in the ice veins from early Holocene to the present time is indicative of a steady positive trend of mean winter air temperatures in the Holocene.

Description: Observations of coastline retreat using contemporary very high resolution satellite and historical aerial imagery were compared to measurements of open water fraction, summer air temperature, and wind. We analysed seasonal and interannual variations of thawing-induced cliff top retreat (thermo-denudation) and marine abrasion (thermo-abrasion) on Muostakh Island in the southern central Laptev Sea. Geomorphometric analysis revealed that total ground ice content on Muostakh is made up of equal amounts of intrasedimentary and macro ground ice and sums up to 87%, rendering the island particularly susceptible to erosion along the coast, resulting in land loss. Based on topographic reference measurements during field campaigns, we generated digital elevation models using stereophotogrammetry, in order to block-adjust and orthorectify aerial photographs from 1951 and GeoEye, QuickBird, WorldView-1, and WorldView-2 imagery from 2010 to 2013 for change detection. Using sea ice concentration data from the Special Sensor Microwave Imager (SSM/I) and air temperature time series from nearby Tiksi, we calculated the seasonal duration available for thermo-abrasion, expressed as open water days, and for thermo-denudation, based on the number of days with positive mean daily temperatures. Seasonal dynamics of cliff top retreat revealed rapid thermo-denudation rates of −10.2 ± 4.5 m a−1 in mid-summer and thermo-abrasion rates along the coastline of −3.4 ± 2.7 m a−1 on average during the 2010–2013 observation period, currently almost twice as rapid as the mean rate of −1.8 ± 1.3 m a−1 since 1951. Our results showed a close relationship between mean summer air temperature and coastal thermo-erosion rates, in agreement with observations made for various permafrost coastlines different to the East Siberian Ice Complex coasts elsewhere in the Arctic. Seasonality of coastline retreat and interannual variations of environmental factors suggest that an increasing length of thermo-denudation and thermo-abrasion process simultaneity favours greater coastal erosion. Coastal thermo-erosion has reduced the island's area by 0.9 km2 (24%) over the past 62 years but shrank its volume by 28 x 106 m3 (40%), not least because of permafrost thaw subsidence, with the most pronounced with rates of ≥− 11 cm a−1 on yedoma uplands near the island's rapidly eroding northern cape. Recent acceleration in both will halve Muostakh Island's lifetime to less than a century.