Description: To reconstruct palaeoclimate and palaeonvironmental conditions in the Northeast Siberian Arctic, we studied late Quaternary permafrost at the Oyogos Yar coast (Dmitry Laptev Strait). New infrared stimulated luminescence ages for distinctive floodplain deposits of the Kuchchugui Suite (112.5±9.6 kyr) and thermokarst-lake deposits of the Krest Yuryakh Suite (102.4±9.7 kyr), respectively, provide new substantial geochronological data and shed light on the landscape history of the Dmitry Laptev Strait region during the Marine Isotope Stage (MIS) 5. Ground ice stable-isotope data are presented together with cryolithological information for eight cryostratigraphic units and are complemented by data from nearby Bol'shoy Lyakhovsky Island. Our combined record of ice-wedge stable isotopes as proxy for past winter climate conditions covers about 200 thousand years and is supplemented by stable isotopes of pore and segregated ice which reflect annual climate conditions overprinted by freezing processes. Our ice wedge stable-isotope data indicate substantial variations in Northeast Siberian Arctic winter climate conditions during the late Quaternary, in particular between Glacial and Interglacial but also over the last millennia to centuries. Stable isotope values of Ice Complex ice wedges indicate cold to very cold winter temperatures about 200 kyr ago (MIS7), very cold winter conditions about 100 kyr ago (MIS5), very cold to moderate winter conditions between about 60 and 30 kyr ago, and extremely cold winter temperatures during the Last Glacial Maximum (MIS2). Much warmer winter conditions are reflected by extensive thermokarst development during the MIS5c and by Holocene ice-wedge stable-isotopes. Modern ice-wedge stable isotopes are most enriched and testify the recent winter warming in the Arctic. Hence, ice-wedge based reconstructions of changes in winter climate conditions add substantial information to those derived from paleoecological proxies stored in permafrost and allow for distinguishing between seasonal trends of past climate dynamics. Future progress in ice-wedge dating and an improved temporal resolution of ice-wedge derived climate information may help to fully explore the palaeoclimatic potential of ice wedges.

Description: This supplement contains results of fossil diatom counting and results and methodology of XRF analysis of a sediment core (RK12) from Lake Kushu (Rebun Island) as well as modern water chemistry data and modern diatom counts of samples from Lake Kushu and Hime-numa Pond (Rishiri Island) in northern Hokkaido, Japan.

Description: Geospatial Data: - Watershed delineation based on hydrology toolbox in ArcGIS (ESRI, version 10.3) - Mapped disturbances based on aerial photographs from 1952 and 1970 (for Ice Creek East, Ice Creek West and Eastern Gully only) and satellite imagery from 2011 (GeoEye-1) and 2015 (WorldView2). Note that no disturbances were found in Slump D creek. Hydrology Data: - Manual flow measurements with the Flo-Mate 2000 Flow Meter different streams on Herschel Island - Runoff data in Ice Creek East - continuous measurements - Runoff data in Ice Creek West - continuous measurements Hydrochemistry Data: - hydrochemistry data of 2016 including pH, conductivity, turbidity, stable water isotopes, solutes, POC and DOC More details on the methods can be found in the accompanying manuscript.

Description: The Antarctic Peninsula is one of the most challenging regions of Antarctica from a climatological perspective, owing to the recent atmospheric and oceanic warming. The steep topography and a lack of long-term and in situ meteorological observations complicate extrapolation of existing climate models to the sub-regional scale. Here, we present new evidence from the northern Antarctic Peninsula to demonstrate how stable water isotopes of firn cores and recent precipitation samples can reveal climatic processes related to nearby oceanic and atmospheric conditions. A noticeable effect of the sea ice cover on local temperatures and atmospheric modes, in particular the Southern Annular Mode (SAM), is demonstrated. In years with large sea ice extension in winter (negative SAM anomaly), an inversion layer in the lower troposphere develops at the coastal zone. Therefore, an isotope-temperature relationship valid for all seasons cannot be concluded. The delta-T relationship rather depends on seasonal variability of oceanic conditions. Transitional seasons (autumn and spring) are both stable seasons with an isotope-temperature gradient of +0.69 per mil/°C. The firn stable isotope composition reveals that the near-surface temperature at the Antarctic Peninsula shows a decreasing trend (-0.33 °C/y) between 2008 and 2014. Moreover, the deuterium excess (d excess) has been demonstrated to be a reliable indicator of seasonal oceanic conditions, and therefore suitable to improve a firn age model based on seasonal d excess variability. The annual accumulation rate in this region is highly variable, ranging between 1060 kg/m**2/y and 2470 kg/m**2/y from 2008 to 2014. The combination of isotopic and meteorological data is key for reconstructing recent climatic conditions with a high temporal resolution in polar regions where no direct observation exists.

Description: Stable water isotope composition (δ¹⁸O, δD, d excess) and accumulation rates of six firn cores from Union Glacier, Ellsworth Mountains, West Antarctica

Description: Ground ice and sedimentary records of a pingo exposure reveal insights into Holocene permafrost, landscape and climate dynamics. Early to mid‐Holocene thermokarst lake deposits contain rich floral and faunal paleoassemblages, which indicate lake shrinkage and decreasing summer temperatures (chironomid‐based TJuly) from 10.5 to 3.5 cal kyr BP with the warmest period between 10.5 and 8 cal kyr BP. Talik refreezing and pingo growth started about 3.5 cal kyr BP after disappearance of the lake. The isotopic composition of the pingo ice (δ18O − 17.1 ± 0.6‰, δD −144.5 ± 3.4‰, slope 5.85, deuterium excess −7.7± 1.5‰) point to the initial stage of closed‐system freezing captured in the record. A differing isotopic composition within the massive ice body was found (δ18O − 21.3 ± 1.4‰, δD −165 ± 11.5‰, slope 8.13, deuterium excess 4.9± 3.2‰), probably related to the infill of dilation cracks by surface water with quasi‐meteoric signature. Currently inactive syngenetic ice wedges formed in the thermokarst basin after lake drainage. The pingo preserves traces of permafrost response to climate variations in terms of ground‐ice degradation (thermokarst) during the early and mid‐Holocene, and aggradation (wedge‐ice and pingo‐ice growth) during the late Holocene.

Description: Stable water isotope signature measured from ice wedges in the Lena Delta, Bykovsky Peninsula. Samples were taken during espedition Lena 2000.