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RADIX (Rapid Access Drilling and Ice eXtraction) is a prospecting drilling system that has been designed, realized and tested on polar ice sheets. The goal of RADIX is to provide rapid, deep access for sampling of ice and downhole physical measurements that inform about ice sheet age and history and the integrity of layering. A 20 mm access hole is drilled with a hydraulic coiled tubing system where the tube consists of a plastic hose. The ice cuttings are flushed to the surface in normal circulation, i.e., between the hose and borehole wall, and can be sampled for analysis. After drilling, a dedicated logger with a 15 mm diameter is deployed into the hole for measuring the geometric orientation of the hole, the temperature profile and the dust content in the surrounding ice (optical dust logger). The equipment has been tested and improved during six field projects in Greenland and Antarctica. It is designed to ultimately drill through a 3000 m ice sheet within roughly 1 week. The greatest depth reached so far was 324 m during the last field project at Little Dome C. [ABSTRACT FROM AUTHOR]

We here describe, document, and make available a wide range of data sets used for annual-layer identification in ice cores from DYE-3, GRIP, NGRIP, NEEM, and EGRIP. The data stem from detailed measurements performed both on the main deep cores and shallow cores over more than 40 years using many different setups developed by research groups in several countries and comprise both discrete measurements from cut ice samples and continuous-flow analysis data. The data series were used for counting annual layers 60 000 years back in time during the construction of the Greenland Ice-Core Chronology 2005 (GICC05) and/or the revised GICC21, which currently only reaches 3800 years back. Now that the underlying data are made available (listed in Table 1) we also release the individual annual-layer positions of the GICC05 timescale which are based on these data sets. We hope that the release of the data sets will stimulate further studies of the past climate taking advantage of these highly resolved data series covering a large part of the interior of the Greenland ice sheet. [ABSTRACT FROM AUTHOR]

We here describe, document, and make available a wide range of data sets used for annual layer identification in ice cores from DYE-3, GRIP, NGRIP, NEEM, and EGRIP. The data stem from detailed measurements performed both on the main deep cores and shallow cores over more than forty years using many different setups developed by research groups in several countries, and comprise both discrete measurements from cut ice samples and continuous-flow analysis data. The data series were used for the construction of the Greenland Ice-Core Chronology 2005 (GICC05) and/or the revised GICC21. Now that the underlying data are made available, we also release the individual annual layer positions of the GICC05 time scale which are based on these data sets. We hope that the release of the data sets will stimulate further studies of the past climate taking advantage of these highly resolved data series covering a large part of the interior of the Greenland ice sheet. [ABSTRACT FROM AUTHOR]

Abstract: Reconstructions of past atmospheric concentrations of greenhouse gases provide unique insight into the biogeochemical cycles and the past radiative forcing in the Earth''s climate system. We present new measurements of atmospheric nitrous oxide along the ice cores of the North Greenland Ice Core Project and Talos Dome sites. Using records of several other ice cores, we are now able to establish the first complete composite nitrous oxide record reaching back to the beginning of the previous interglacial about 140,000yr ago. On the basis of such composite ice core records, we further calculate the radiative forcing of the three most important greenhouse gases carbon dioxide, methane and nitrous oxide during more than a full glacial–interglacial cycle. Nitrous oxide varies in line with climate, reaching very low concentrations of about 200 parts per billion by volume during Marine Isotope Stages 4 and 2, and showing substantial responses to millennial time scale climate variations during the last glacial. A large part of these millennial time scale variations can be explained by parallel changes in the sources of methane and nitrous oxide. However, as revealed by high-resolution measurements covering the Dansgaard/Oeschger events 17 to 15, the evolution of these two greenhouse gases may be decoupled on the centennial time scale. Carbon dioxide and methane concentrations do not reach interglacial levels in the course of millennial time scale climate variations during the last glacial. In contrast, nitrous oxide often reaches interglacial concentrations in response to both, glacial terminations and Dansgaard/Oeschger events. This indicates, from a biogeochemical point of view, similar drivers in both temporal cases. While carbon dioxide and methane concentrations are more strongly controlled by climate changes in high latitudes, nitrous oxide emissions changes may mainly stem from the ocean and/or from soils located at low latitudes. Accordingly, we speculate that high latitudes could play the leading role to trigger glacial terminations. [Copyright &y& Elsevier]

After the NEEM (Greenland) deep ice-core drilling was declared terminated with respect to developing stratigraphic climate reconstructions, efforts were turned toward collecting basal icesheet debris and, if possible, drilling into the bedrock itself. In 2010, several meters of banded debrisrich ice were obtained under normal ice-drilling operations with the NEEM version of the Hans Tausen (HT) drill, but further penetration was obstructed by a rock in the path of the drill head at 2537.36 m. During short campaigns in 2011 and 2012, attempts were made to penetrate further using various reinforced ice cutters mounted on the HT drill head, tailored to cut through rock. These had some success in penetrating coarse material, but produced severely damaged cutters. Additionally a 51 mm diameter diamond cutting tipped rock drill was adapted to fit the NEEM drill. With this device, several additional meters of core containing subglacial sediments, rocks and rock fragments were collected. With these tools 1.39 m of additional material were obtained during the 2011 field season, and 7.1 m during 2012. Subglacial water refreezing into the newly formed borehole hindered further penetration, and the bedrock interface was not reached before final closure of the NEEM Camp. [ABSTRACT FROM AUTHOR]