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Greenland ice sheet rainfall is expected to increase under a warming climate. Yet, there have been no active long‐term in‐situ rainfall records on the ice sheet due to observational difficulties. Here, we utilize the state‐of‐the‐art 5 km polar non‐hydrostatic regional climate model NHM‐SMAP to evaluate the ice sheet's rainfall over 40 years (1980–2019). The largest trends include a fourfold increase in annual rainfall for the northwestern ice sheet; 3.1 Gt year−1 or 12 mm m−2 year−1. September ice‐sheet‐wide rainfall amount and intensity increase by 7.5 Gt month−1 and 20.8 mm h−1 year−1. In the last two decades, the increasing September maximum hourly rainfall rate exceeded 50 mm h−1 six times. The increased surface water delivery has numerous implications, including for snow metamorphism and ice flow dynamics. Plain Language Summary: We find that rainfall has increased over the Greenland ice sheet from 1980 to 2019. Among the eight major ice‐sheet drainage areas, the northwestern sector stands out as an increasing rainfall hotspot where the annual rainfall has increased fourfold. For the entire ice sheet, September's total rainfall and its intensity increased by 224% and 54% above the 1981–2010 baseline over the last 40 years. An increase in late melt season rainfall is expected to contribute to an increase in late summer snow and ice melt. Our results provide the first detailed quantification of the state of ice sheet rainfall climatology. Key Points: A 5 km horizontal resolution non‐hydrostatic regional climate model is used to evaluate Greenland ice sheet rainfall from 1980 to 2019The northwestern sector stands out as a hotspot of increasing rainfallBoth the amount and intensity of September ice‐sheet‐wide rainfall have significantly increased in the 40 years from 1980 to 2019 [ABSTRACT FROM AUTHOR]

The Greenland Ice Sheet harbours a wealth of microbial life, yet the total biomass stored or exported from its surface to downstream environments is unconstrained. Here, we quantify microbial abundance and cellular biomass flux within the near-surface weathering crust photic zone of the western sector of the ice sheet. Using groundwater techniques, we demonstrate that interstitial water flow is slow (~10−2 m d−1), while flow cytometry enumeration reveals this pathway delivers 5 × 108 cells m−2 d−1 to supraglacial streams, equivalent to a carbon flux up to 250 g km−2 d−1. We infer that cellular carbon accumulation in the weathering crust exceeds fluvial export, promoting biomass sequestration, enhanced carbon cycling, and biological albedo reduction. We estimate that up to 37 kg km−2 of cellular carbon is flushed from the weathering crust environment of the western Greenland Ice Sheet each summer, providing an appreciable flux to support heterotrophs and methanogenesis at the bed. Microbes that colonise ice sheet surfaces are important to the carbon cycle, but their biomass and transport remains unquantified. Here, the authors reveal substantial microbial carbon fluxes across Greenland's ice surface, in quantities that may sustain subglacial heterotrophs and fuel methanogenesis. [ABSTRACT FROM AUTHOR]

Combined records of snow accumulation rate, δ18O and deuterium excess were produced from several shallow ice cores and snow pits at NEEM (North Greenland Eemian Ice Drilling), covering the period from 1724 to 2007. They are used to investigate recent climate variability and characterise the isotope-temperature relationship. We find that NEEM records are only weakly affected by inter-annual changes in the North Atlantic Oscillation. Decadal δ18O and accumulation variability is related to North Atlantic sea surface temperature and is enhanced at the beginning of the 19th century. No long-term trend is observed in the accumulation record. By contrast, NEEM δ18O shows multidecadal increasing trends in the late 19th century and since the 1980s. The strongest annual positive δ18O values are recorded at NEEM in 1928 and 2010, while maximum accumulation occurs in 1933. The last decade is the most enriched in δ18O (warmest), while the 11-year periods with the strongest depletion (coldest) are depicted at NEEM in 1815-1825 and 1836-1846, which are also the driest 11-year periods. The NEEM accumulation and δ18O records are strongly correlated with outputs from atmospheric models, nudged to atmospheric reanalyses. Best performance is observed for ERA reanalyses. Gridded temperature reconstructions, instrumental data and model outputs at NEEM are used to estimate the multidecadal accumulation-temperature and δ18O-temperature relationships for the strong warming period in 1979-2007. The accumulation sensitivity to temperature is estimated at 11±2% °C-1 and the δ18O-temperature slope at 1.1±0.2‰ °C-1, about twice as large as previously used to estimate last interglacial temperature change from the bottom part of the NEEM deep ice core. [ABSTRACT FROM AUTHOR]

This study presents the application of a costeffective, unmanned aerial vehicle (UAV) to investigate calving dynamics at a major marine-terminating outlet glacier draining the western sector of the Greenland ice sheet. The UAV was flown over Store Glacier on three sorties during summer 2013 and acquired over 2000 overlapping, geotagged images of the calving front at an ~40 cm ground sampling distance. Stereo-photogrammetry applied to these images enabled the extraction of high-resolution digital elevation models (DEMs) with vertical accuracies of ±1.9m which were used to quantify glaciological processes from early July to late August 2013. The central zone of the calving front advanced by ~500 m, whilst the lateral margins remained stable. The orientation of crevasses and the surface velocity field derived from feature tracking indicates that lateral drag is the primary resistive force and that ice flow varies across the calving front from 2.5md–1 at the margins to in excess of 16md–1 at the centreline. Ice flux through the calving front is 3.8×107 m3 d–1, equivalent to 13.9 Gt a–1 and comparable to flux-gate estimates of Store Glacier's annual discharge. Water-filled crevasses were present throughout the observation period but covered a limited area of between 0.025 and 0.24% of the terminus and did not appear to exert any significant control over fracture or calving. We conclude that the use of repeat UAV surveys coupled with the processing techniques outlined in this paper have great potential for elucidating the complex frontal dynamics that characterise large calving outlet glaciers. [ABSTRACT FROM AUTHOR]

The article presents a study on meltwater retention, surface runoff, and delayed release of meltwater within the Greenland ice sheet as of 2013. Topics include increases in meltwater runoff from 2000 to 2013; meltwater storage for an ice sheet watershed near Kangerlussuaq; englacial and subglacial meltwater storage; and the effect of melting season ice sheet runoff on downstream rivers. Rising air temperatures, declining surface mass balance, and ice dynamics are also discussed.

A combined analysis of remote sensing observations, regional climate model (RCM) outputs and reanalysis data over the Greenland ice sheet provides evidence that multiple records were set during summer 2012. Melt extent was the largest in the satellite era (extending up to ~97% of the ice sheet) and melting lasted up to ~2 months longer than the 1979-2011 mean. Model results indicate that near surface temperature was~3 standard deviations (σ) above the 1958- 2011 mean, while surface mass balance (SMB) was ~3σ below the mean and runoff was 3.9σ above the mean over the same period. Albedo, exposure of bare ice and surface mass balance also set new records, as did the total mass balance with summer and annual mass changes of, respectively, -627 Gt and -574 Gt, 2σ below the 2003-2012 mean. We identify persistent anticyclonic conditions over Greenland associated with anomalies in the North Atlantic Oscillation (NAO), changes in surface conditions (e.g., albedo, surface temperature) and preconditioning of surface properties from recent extreme melting as major driving mechanisms for the 2012 records. Less positive if not increasingly negative SMB will likely occur should these characteristics persist. [ABSTRACT FROM AUTHOR]

We present detailed records of lake discharge, ice motion and passive seismicity capturing the behaviour and processes preceding, during and following the rapid drainage of a ~4 km2 supraglacial lake through 1.1-km-thick ice on the western margin of the Greenland Ice Sheet. Peak discharge of 3300m3 s-1 coincident with maximal rates of vertical uplift indicates that surface water accessed the ice-bed interface causing widespread hydraulic separation and enhanced basal motion. The differential motion of four global positioning system (GPS) receivers located around the lake record the opening and closure of the fractures through which the lake drained. We hypothesise that the majority of discharge occurred through a ~3-km-long fracture with a peak width averaged across its wetted length of ~0.4 m. We argue that the fracture's kilometre-scale length allowed rapid discharge to be achieved by combining reasonable water velocities with sub-metre fracture widths. These observations add to the currently limited knowledge of in situ supraglacial lake drainage events, which rapidly deliver large volumes of water to the ice-bed interface. [ABSTRACT FROM AUTHOR]

The article presents a study which investigates the spatial dependence and impact of Greenland ice sheet albedo feedback over 12 summer season since 2000. The study employs satellite-derived surface albedo with surface downward solar irradiance and calibrated climate models for surface air temperature. Results shows increased warm air advection in the west side of ice sheet surface, and increased surface downward shortwave flux.

The article presents the correct information on the mistaken publisher's media release on the shrinkage of permanent ice cover in Greenland published on a map in the 2011 edition of the "Times Comprehensive Atlas of the World." It states that the 2011 ice margin encloses the ice sheet and ice bodies, and an alternative Greenland land surface classification yields represent standard deviation of 12 annual classifications. It also discusses the magnitude of sinkage rate and mass budget.

The article presents a study which offers a first synoptic assessment of remotely-sensed buoyant coastal sediment plumes around Greenland and links them to ice sheet runoff from land- and marine-terminating outlet glaciers. It notes that such remotely-sensed sediment plumes appear to supply viable evidence of meltwater release despite known complexities in plume formation and development process. The authors use MODIS satellite imagery to average surface suspended sediment concentration (SSC).

The article explores the climatic sensitivity and hydrology of Greenland ice sheets near Kangerlussuaq, as well as their contributions to sea level rise. It presents a hydrological dataset which contains measurements of rise water level and discharge for 3 sites along the northern tributary of Akuliarusiarsuup Kuua River. Furthermore, it notes the association of greatest discharge data with streambed elevation change and measurements.

The article presents an evaluation on the climate of the ice sheet in Greenland. It notes that the RACMO2/GR regional atmospheric climate model was used in the assessment of the characteristics of Greenland atmosphere. It also determines the variations in the surface mass balance (SMB) of the Greenland Ice Sheet (GrIS).

The article offers information on the condition of ice sheet in Greenland in 2015. Topics include the effect of ice runoff on sea level, ocean thermohaline circulation, and global climate, average albedo for the Greenland ice sheet in summer 2015, and advancement of Petermann Glacier and Kangerdlugssuaq Glacier.