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Palynomorphs are one of the few groups of fossils that provide biostratigraphic control in marine to nonmarine rocks and can be applied as proxies for paleoenvironmental and paleoclimatic interpretations. Their utility is enhanced by their microscopic size, which is usually less than 200 micrometres; they are thus easily recovered from small rock samples. They occur throughout the Phanerozoic and are therefore invaluable in refining biostratigraphic control of Arctic successions in Alaska, Arctic Canada, Greenland, northern Europe, and northern Russia. The objective of the Circum-Arctic Palynological Event (CAPE) Stratigraphy series of papers is to integrate data published on Arctic palynomorphs to delineate palynological events (palynoevents) across the Arctic for the Silurian to Cenozoic. Once the series of papers is complete, the data will also be used to compile a TimeScale Creator datapack that can be updated and calibrated on an ongoing basis. Palynoevents include taxon originations (first occurrences or FOs) and extinctions (last occurrences, or LOs) and some abundance events. The palynoevents are correlated with established chronostratigraphic horizons such as bases of ammonoid zones or stages, and hence their chronostratigraphy is independent of the absolute time scale in millions of years. In addition to the palynostratigraphic papers, the series includes a paper detailing the paleogeography of the circum-Arctic regions, including informative maps, as well as a paper providing a palynological perspective of the Cenozoic shift from greenhouse to icehouse conditions. [ABSTRACT FROM AUTHOR]

Featured Application: This work gives indications for cleaning and preservation of ice cores, which will be drilled in Antarctica during the EU project Beyond EPICA Oldest Ice and provides general guidelines for ice drilling activities and preservation of ice cores. To reconstruct climate history of the past 1.5 Million years, the project: Beyond EPICA Oldest Ice (BEOI) will drill about 2700 m of ice core in East Antarctica (2021–2025). As drilling fluid, an aliphatic ester fluid, EstisolTM 140, will be used. Newly drilled ice cores will be retrieved from the drill soaked in fluid, and this fluid should be removed from the cores. Most of it will be vacuum-cleaned off in a Fluid Extraction Device and wiped off with paper towels. Based on our experiences in Greenland deep ice coring, most of the residual fluid can be removed by storing the cores openly on shelves in a ventilated room. After a week of "drying", the cores have a dry feel, handling them do not give "wet" gloves and they can easily be marked with lead pencils. This paper presents a theoretical investigation and some simple testing on the "drying" process. The rates of sublimation of ice and evaporation of fluid have been calculated at different temperatures. The calculations show that sublimation of the ice core should not occur, and that evaporation of fluid should be almost negligible. Our test results support these calculations, but also revealed significant fluid run-off and dripping, resulting in the removal of most of the fluid in a couple of days, independent of temperature and ventilation conditions. Finally, we discuss crucial factors that ensure optimal long-term ice core preservation in storage, such as temperature stability, defrosting cycles of freezers and open core storage versus storage of cores in insulated crates. [ABSTRACT FROM AUTHOR]

The article offers world news briefs related to meteorology. The subrotors and the internal structure of the parent rotor lifts off the surface and breakdown along the edge of the lee wave through Kelvin-Helmholtz like instability. Greenland extends one quarter of the distance between the North Pole and Equator averaging 1.5 kilometer (km) in height and reaching skyward more than 3.5 km. The Global Precipitation Climatology Project (GPCP) offers the opportunity to analyze climate variation.

This paper summarizes the physical and human geography of the southwestern part of Greenland, stretching from Upernavik at the southern end of Melville Bay in approximately 73° N latitude, southward to Cape Farewell in approximately 60° N latitude. It is along this southwestern coast of Greenland that modernization has token place, and it is here that development is proceeding rapidly. Since about six-sevenths of Greenland is buried under ice, only a narrow strip of land is exposed along the coastline, never exceeding one hundred miles. Most of the 22,000 people live along this coastal fringe. Of mixed Eskimo and European origin, these "Greenlanders" have increased rapidly in numbers in the last half-century, and are now straining the restricted natural resources of the country. Denmark, which has governed the country for almost two centuries, has traditionally maintained a strict policy of isolating Greenland from outside contacts. This has protected the natives and given them a high standard of education, reasonably good health, and a carefully planned economy insulating them from the vagaries of world prices. Today this traditional policy is being questioned. Intensive efforts are now being made to modernize West Greenland through building efficient harbors, power stations, fish processing plants, by raising still higher educational standards, and by speeding up Greenland's self-government. [ABSTRACT FROM AUTHOR]

The article reviews the 2009 special issue titled "Norse Greenland: Selected Papers From the Hvalsey Conference 2008," of the periodical "Journal of the North Atlantic."

Estuary systems are well-defined semi-enclosed systems which are strongly influenced by their terrestrial and marine boundaries. In this paper we investigate the bio-optical conditions in the water column of two neighboring estuary systems, Uummannaq Fjord and Vaigat-Disko Bay, in West Greenland. Though close to each other, the systems differ by their hydrographic structure influencing the bio-optical conditions and subsequently the biological activities. Both systems show high inorganic suspended particulate matter (SPMi) concentrations near freshwater respective melt water influxes (max. of 15.28mgL-1 at the surface) and low colored dissolved organic matter (aCDOM@350 nm, < 1.50m-1) abundance throughout the estuaries. Chlorophyll as an indicator of phytoplankton was solely high in the Vaigat (max. of 11.44µgL-1) representing the outflow arm of the Disko Bay. Light penetration depth as indicated by the 1% depth of Photosynthetically Available Radiation (PAR) was dominated by chlorophyll and SPMi alike and reached from 12.2 to 41.2m. Based on these characteristics an effective two component parameterization for the diffuse attenuation coeffcient kPAR was developed enabling to model light penetration depth as a relevant factor for biooptical studies in Arctic environments under glacial melt water influence. [ABSTRACT FROM AUTHOR]

Few hydrological studies have been made in Greenland, other than on glacial hydrology associated with the ice sheet. Understanding permafrost hydrology and hydroclimatic change and variability, however, provides key information for understanding climate change effects and feedbacks in the Arctic landscape. This paper presents a new extensive and detailed hydrological and meteorological open access dataset, with high temporal resolution from a 1.56 km2 permafrost catchment with a lake underlain by a through talik close to the ice sheet in the Kangerlussuaq region, western Greenland. The paper describes the hydrological site investigations and utilized equipment, as well as the data collection and processing. The investigations were performed between 2010 and 2013. The high spatial resolution, within the investigated area, of the dataset makes it highly suitable for various detailed hydrological and ecological studies on catchment scale. The dataset is availble for all users via the PANGAEA database, http://doi.pangaea.de/10.1594/PANGAEA.836178. Please note this dataset is under review and recommended not to be used before the final version of the manuscript is accepted for publication. [ABSTRACT FROM AUTHOR]

At present, a variety of global remote sensing surface downwelling longwave radiation (SDL) products are used for atmospheric science research; however, there are few studies on the quantitative evaluation of differences among different SDL products. In order to evaluate the differences among different SDL products quantitatively, we have selected three commonly used SDL products—Clouds and the Earth's Radiant Energy System-Synoptic Radiative Fluxes and Clouds (CERES-SYN), the European Centre for Medium Range Weather Forecasts-Surface Radiation Budget (ECMWF-SRB) and the Global Energy and Water Exchanges Project-Surface Radiation Budget (GEWEX-SRB)—to comprehensively study in this paper. The results show that there are significant differences among the three SDL products in some areas, such as in the Arctic, the Antarctic, the Sahara, the Tibet Plateau, and Greenland. The maximum absolute root mean square error (RMSEab) in these areas is greater than 20 Wm−2, the maximum relative root mean square error (RMSEre) is greater than 20%, the maximum and minimum absolute mean bias error (MBEab) are about 20 Wm−2 and −20 Wm−2, respectively, and the maximum and minimum relative mean bias error (MBEre) are about 10% and −10%, respectively. Among the three SDL products, the difference between the ECMWF-SRB and GEWEX-SRB is the most significant. In addition, this paper also analyzed the differences among different SDL products based on three aspects. Firstly, the differences among the three SDL products show that there is significant seasonality, and the differences among different months may vary greatly. However, the differences are not sensitive to years. Secondly, there are some differences in cloud-forcing radiative fluxes (CFRFs) of different SDL products, which is also an important factor affecting the difference between different SDL products. Finally, in the process of converting high temporal resolution SDL products into monthly SDL products, data processing also affects the difference between different SDL products. [ABSTRACT FROM AUTHOR]

We present first results from a coupled model setup, consisting of a state-of-the-art ice sheet model (RIMBAY), and the community earth system model COSMOS. We show that special care has to be provided in order to ensure physical distributions of the forcings, as well as numeric stability of the involved models. We demonstrate that a statistical downscaling is crucial for ice sheet stability, especially for southern Greenland where surface temperature are close to the melting point. The simulated ice sheets are stable when forced with pre-industrial greenhouse gas parameters, with limits comparable with present day ice orography. A setup with high CO2 level is used to demonstrate the effects of dynamic ice sheets compared to the standard parameterisation; the resulting changes on ocean circulation will also be discussed. [ABSTRACT FROM AUTHOR]

Permafrost is degrading across regions of the Arctic, which can lead to increases in nutrient concentrations in surface freshwaters. The oligotrophic state of many arctic lakes suggests that enhanced nutrient inputs may have important effects on these systems, but little is known about microbial nutrient limitation patterns in these lakes. We investigated microbial extracellular enzyme activities (EEAs) to infer seasonal nutrient dynamics and limitation across 24 lakes in southwest Greenland during summer (June and July). From early to late summer, enzyme activities that indicate microbial carbon (C), nitrogen (N), and phosphorus (P) demand increased in both the epilimnia and hypolimnia by 74% on average. Microbial investment in P acquisition was generally higher than that for N. Interactions among EEAs indicated that bacteria were primarily P limited. Dissolved organic matter (DOM, measured as dissolved organic carbon) was strongly and positively correlated with microbial P demand (R2 = 0.84 in July), while there were no relationships between DOM and microbial N demand. Microbial P limitation in June epilimnia (R² = 0.67) and July hypolimnia (R2 = 0.57) increased with DOM concentration. The consistency of microbial P limitation from June to July was related to the amount of DOM present, with some low DOM lakes becoming N-limited in July. Our results suggest that future changes in P or DOM inputs to these lakes are likely to alter microbial nutrient limitation patterns. [ABSTRACT FROM AUTHOR]

Reconstructing the opening of the Labrador Sea and Baffin Bay between Greenland and North America remains controversial. Recent seismic data suggest that magnetic lineations along the margins of the Labrador Sea, originally interpreted as seafloor spreading anomalies, may lie within the crust of the continent-ocean transition. These data also suggest a more seaward extent of continental crust within the Greenland margin near the Davis Strait than assumed in previous full-fit reconstructions. Our study focuses on reconstructing the full-fit configuration of Greenland and North America using an approach that considers continental deformation in a quantitative manner. We use gravity inversion to map crustal thickness across the conjugate margins, and assimilate observations from available seismic profiles and potential field data to constrain the likely extent of different crustal types. We derive end-member continental margin restorations following alternative interpretations of published seismic profiles. The boundaries between continental and oceanic crust (COB) are restored to their prestretching locations along small circle motion paths across the region of Cretaceous extension. Restored COBs are fitted quantitatively to compute alternative total-fit reconstructions. A preferred full-fit model is chosen based on the strongest compatibility with geological and geophysical data. Our preferred model suggests that (i) the COB lies oceanward of magnetic lineations interpreted as magnetic anomaly 31 (70 Ma) in the Labrador Sea, (ii) all previously identified magnetic lineations landward of anomaly 27 reflect intrusions into continental crust, and (iii) the Ungava fault zone in Davis Strait acted as a leaky transform fault during rifting. This robust plate reconstruction reduces gaps and overlaps in the Davis Strait and suggests that there is no need for alternative models proposed for reconstructions of this area including additional plate boundaries in North America or Greenland. Our favored model implies that break up and formation of continent-ocean transition (COT) first started in the southern Labrador Sea and Davis Strait around 88Ma and then propagated north and southwards up to onset of real seafloor spreading at 63Ma in the Labrador Sea. In the Baffin Bay, continental stretching lasted longer and actual break up and seafloor spreading started around 61Ma (Chron 26). [ABSTRACT FROM AUTHOR]

Melting of the Greenland Ice Sheet (GrIS) is accelerating and will contribute significantly to global sea level rise during the 21st century. Instrumental data on GrIS melting only cover the last few decades, and proxy data extending our knowledge into the past are vital for validating models predicting the influence of ongoing climate change. We investigated a potential meltwater proxy in Godthåbsfjord (West Greenland), where glacier meltwater causes seasonal excursions with lower oxygen isotope water (δ18Ow) values and salinity. The blue mussel (Mytilus edulis) potentially records these variations, because it precipitates its shell calcite in oxygen isotopic equilibrium with ambient seawater. As M. edulis shells are known to occur in raised shorelines and kitchen middens from previous Holocene warm periods, this species may be ideal in reconstructing past meltwater dynamics. We investigate its potential as a palaeomeltwater proxy. First, we confirmed that M. edulis shell calcite oxygen isotope (δ18Oc) values are in equilibrium with ambient water and generally reflect meltwater conditions. Subsequently we investigated if this species recorded the full range of δ18Ow values occurring during the years 2007 to 2010. Results show that δ18Ow values were not recorded at very low salinities (<~ 19), because the mussels appear to cease growing. This implies that M. edulis δ18Ow values are suitable in reconstructing past meltwater amounts in most cases, but care has to be taken that shells are collected not too close to a glacier, but rather in the mid region or mouth of the fjord. The focus of future research will expand on the geographical and temporal range of the shell measurements by sampling mussels in other fjords in Greenland along a south-north gradient, and by sampling shells from raised shorelines and kitchen middens from prehistoric settlements in Greenland. [ABSTRACT FROM AUTHOR]

The article presents a study which discusses the observation of the mass balance along the K-transects in West Greenland from 1990-2011. It says that a small correction for height changes was included due to ice displacement over the course of time. It adds that the data set of surface mass balance can be used for validation of satellite observations and regional climate models both with respect to the interannual variability.

The article offers information on the development of a 1200-year proxy index of reconstruction of volcanic eruptions that is based on sulphate records found in ice cores of Antarctic and Greenland. It states that processes in the reconstruction include calibration with satellite aerosol optical depth (AOD), identification of new categories of eruptions, and specification of power shortwave scaling. It adds the introduction of estimate on the particle size that affect the stratospheric aerosols.

The 1970s and 1980s saw the appearance of many papers on the topics of synergy, antagonism, and similar concepts of causal interactions and interdependence of effects, with a special emphasis on distinguishing these concepts from that of statistical interaction – the need for a product term in a model. As an example, Miettinen defined "synergism" as "the existence of instances in which both risk factors are needed for the effect", whereas "antagonism" is where "at least one [factor] can block the solo effect of the other". In response, Greenland and Poole constructed a systematic analysis of 16 possible individual response patterns in a deterministic causal model for two binary exposure variables, and showed how these patterns can be mapped onto nine types of sufficient causes, which in turn can be simplified into four intuitive categories. Although these and other papers recognized that epidemiology cannot directly study biological mechanisms underlying interaction, they showed how it can usefully study causal and preventive interdependence – which, despite its mechanistic agnosticism, has important implications for clinical decision making as well as for public health. [ABSTRACT FROM AUTHOR]

Over the past 20 years, the Gravity Recovery and Climate Experiment (GRACE), and its successor mission, GRACE‐Follow On (GRACE‐FO) have made significant contributions to time‐variable gravity field modeling. A Chinese low‐low satellite‐to‐satellite tracking gravimetry mission (i.e., Chinese future gravimetry mission) has been confirmed to be selected as the polar‐orbiting satellite gravimetry mission for China, because of the capability to collect gravity data globally. However, the analysis of potential contributions to geosciences from GRACE‐FO coupling with the Chinese future gravimetry mission is still limited. This study combines GRACE‐FO and Chinese future gravimetry missions as the Dual GRACE‐like Polar satellite Constellation (DGPC). By carefully choosing the initial orbit parameters of the Chinese future gravimetry mission with the differential evolution algorithm, the DGPC is expected to mitigate the temporal aliasing effects by improving the temporal resolution of time‐variable gravity solutions (i.e., 1‐day and 3‐day solutions). Regarding the spectral‐domain evaluation, zonal, tesseral, and sectorial coefficients estimated by the DGPC show approximately 6.01%–13.42% noise reductions compared with GRACE‐FO. Regarding the spatial‐domain evaluation, the DGPC can suppress noises of about 39.44% and 31.12% in annual amplitude and long‐term trend, respectively. On this basis, this paper analyzes the effectiveness of the DGPC in potential contributions to geosciences (e.g., hydrology, glaciology, and seismology). Specifically, the DGPC can improve accuracy by about 36.96%, 25.85%, and 33.16% with respect to GRACE‐FO for signals in the subhumid basin, signals of ice‐sheet mass balance over Greenland, and coseismic displacement of the fault zone, respectively. In general, the potential capability for high‐frequency signals recovery of the DGPC would facilitate contributions of satellite gravimetry to geosciences. Plain Language Summary: The Gravity Recovery And Climate Experiment (GRACE) mission and its successor GRACE Follow On (GRACE‐FO) have made significant contributions to time‐variable gravity field modeling. A polar gravity satellite mission (i.e., Chinese future gravimetry mission) has been confirmed to be selected as the polar‐orbiting satellite gravimetry mission for China because of its capability to collect gravity data globally. Including the GRACE‐FO mission, it is expected that there will be two polar pairs of gravity satellites (i.e., dual GRACE‐like polar satellite constellation) simultaneously within the next few years. What can we expect from the dual GRACE‐like polar satellite constellation? In this study, we introduce an optimization algorithm (i.e., differential evolution algorithm) to carefully choose the initial orbit parameters of the Chinese future gravimetry mission. The dual GRACE‐like polar satellite constellation has been demonstrated to have the potential to mitigate the temporal aliasing effects of time‐variable gravity solutions. It is found that the dual GRACE‐like polar satellite constellation can improve accuracy by about 36.96%, 25.85%, and 33.16% with respect to GRACE‐FO for signals in the subhumid basin, signals of ice‐sheet mass balance over Greenland, and coseismic displacement of the fault zone, respectively. The temporal improvement of Earth's mass transport estimated by coupling GRACE‐FO with a Chinese polar gravity satellite mission would facilitate contributions of satellite gravimetry to geosciences. Key Points: This paper introduces the differential evolution algorithm into the design of the dual Gravity Recovery And Climate Experiment (GRACE)‐like polar satellite constellationImproving the temporal resolution of time‐variable gravity solutions can potentially contribute to mitigating the temporal aliasing effectsThe dual GRACE‐like polar satellite constellation has high‐frequency signal recovery capabilities and stimulates potential contributions to geosciences [ABSTRACT FROM AUTHOR]

The Fourth IPCC Assessment Report concluded that ice-sheet flow models are unable to forecast the current increase of polar ice sheet discharge and the associated contribution to sea-level rise. Since then, the glaciological community has undertaken a huge effort to develop and improve a new generation of ice-flow models, and as a result, a significant number of new ice-sheet models have emerged. Among them is the parallel finite-element model Elmer/Ice, based on the open-source multi-physics code Elmer. It was one of the first full-Stokes models used to make projections for the evolution of the whole Greenland ice sheet for the coming two centuries. Originally developed to solve local ice flow problems of high mechanical and physical complexity, Elmer/Ice has today reached the maturity to solve larger scale problems, earning the status of an ice-sheet model. Here, we summarise almost 10 yr of development performed by different groups. We present the components already included in Elmer/Ice, its numerical performance, selected applications, as well as developments planned for the future. [ABSTRACT FROM AUTHOR]

The last glacial period has been punctuated by two types of abrupt climatic events, the Dansgaard-Oeschger (DO) and Heinrich (HE) events. These events, recorded in Greenland ice and in marine sediments, involved changes in the Atlantic Meridional Overturning Circulation (AMOC) and led to major changes in the terrestrial biosphere. Here we use the dynamical global vegetation model ORCHIDEE to simulate the response of vegetation to abrupt changes in the AMOC strength. To do so, we force ORCHIDEE off-line with outputs from the IPSL CM4 general circulation model, in which we have forced the AMOC to change by adding freshwater fluxes in the North Atlantic. We investigate the impact of a collapse and recovery of the AMOC, at different rates, and focus on Western Europe, where many pollen records are available to compare with. The impact of an AMOC collapse on the European mean temperatures and precipitations simulated by the GCM is relatively small but sufficient to drive an important regression of forests and expansion of grasses in ORCHIDEE, in qualitative agreement 15 with pollen data for an HE event. On the contrary, a run with a rapid shift of the AMOC to an hyperactive state of 30 Sv, mimicking the warming phase of a DO event, does not exhibit a strong impact on the European vegetation compared to the glacial control state. For our model, simulating the impact of an HE event thus appears easier than simulating the abrupt transition towards the interstadial phase of a DO. For both a collapse or a recovery of the AMOC the vegetation starts to respond to climatic changes immediately but reaches equilibrium about 200 yr after the climate equilibrates, suggesting a possible bias in the climatic reconstructions based on pollen records, which assume equilibrium between climate and vegetation. However, our study does not take into account vegetation feedbacks on the atmosphere. [ABSTRACT FROM AUTHOR]

During 2008 and 2009 we applied coincident Earth observation data collected from multiple sensors (RA2, AATSR and MERIS, mounted on the European Space Agency satellite Envisat) to characterise environmental conditions and net sea-air fluxes of CO2 in three Arctic seas (Greenland, Barents, Kara) to assess net CO2 sink sensitivity due to changes in temperature, salinity and sea ice duration arising from future climate scenarios. During the study period the Greenland and Barents Seas were net sinks for atmospheric CO2, with sea-air fluxes of -34±13 and -13±6 TgC yr-1, respectively and the Kara Sea was a weak net CO2 source with a sea-air flux of +1.5±1.1 Tg Cyr-1 . The combined net CO2 sea-air flux from all three was -45±18 Tg Cyr-1 . In a sensitivity analysis we varied temperature, salinity and sea ice duration. Variations in temperature and salinity led to modification of the transfer velocity, solubility and partial pressure of CO2 taking into account the resultant variations in alkalinity and dissolved organic carbon (DOC). Our results showed that warming had a strong positive effect on the annual net sea-air flux of CO2 (i.e. reducing the sink), freshening had a strong negative effect and reduced sea ice duration had a small but measurable positive effect. In the climate change scenario examined, the effects of warming in just over a decade of climate change up to 2020 outweighed the combined effects of freshening and reduced sea ice duration. Collectively these effects gave a net sea-air flux change of +3.5 Tg C in the Greenland Sea, +5.5 Tg C in the Barents Sea and +1.4 Tg C in the Kara Sea, reducing the Greenland and Barents sinks by 10% and 50% respectively, and increasing the weak Kara Sea source by 64%. Overall, the regional flux changed by +10.4 TgC, reducing the regional sink by 23%. In terms of CO2 sink strength we conclude that the Barents Sea is the most susceptible of the three regions to the climate changes examined. Our results imply that the region will cease to be a net CO2 sink by 2060. [ABSTRACT FROM AUTHOR]

In this paper, we consider four scenarios for economic optimal management of a fisheries resource by a high sea and coastal fleet segment. These scenarios differ with respect to whether a common or two separate fish stocks are considered and whether the profit from land-based processing is included. The model is parametrized using the Greenland halibut fishery on the west coast of Greenland as an empirical case. For this fishery, we show that the relative ranking of the optimal high sea industry harvest and profit compared to the coastal industry harvest and profit depends on the chosen scenario. When comparing the scenarios for optimal management and the actual situation, we find that the fish stock tends to be overexploited. [ABSTRACT FROM AUTHOR]

This study investigates how warming and changes in precipitation may affect the cycling of carbon (C) in tundra soils, and between high arctic tundra and the atmosphere. We quantified ecosystem respiration (Reco) and soil pore space CO2 in a polar semi-desert under current and future climate conditions simulated by long-term experimental warming (+2 °C, +4 °C), water addition (+50% summer precipitation) and a combination of both (+4 °C x +50% summer precipitation). We also measured the 14C content of Reco and soil CO2 to distinguish young C cycling rapidly between the atmosphere and the ecosystem from older C stored in the soil for centuries to millennia. We identified changes in the amount and timing of precipitation as a key control of the magnitude, seasonality and sources of Reco in a polar semi-desert. Throughout each summer, small (<4 mm) precipitation events during drier periods triggered the release of very old C pulses from the deep soil, while larger precipitation events (>4 mm), more winter snow and experimental irrigation were associated with higher Reco fluxes and the release of recently-fixed (young) plant C. Warmer summers and experimental warming also resulted in higher Reco fluxes (+2 °C > +4 °C), but coincided with losses of older C. We conclude that in high arctic dry tundra systems, future magnitudes and patterns of old C emissions will be controlled as much by the summer precipitation regime and winter snowpack as by warming. The release of older soil C is of concern as it may lead to net C losses from the ecosystem. Therefore, reliable predictions of precipitation amounts, frequency, and timing are required to predict the changing C cycle in the High Arctic. [ABSTRACT FROM AUTHOR]

The interannual to decadal variability of the transport of anthropogenic carbon dioxide (Cant) across the Subpolar North Atlantic (SPNA) is investigated, using data of the OVIDE high resolution transoceanic section, from Greenland to Portugal, occupied six times from 1997 to 2010. The transport of Cant across this section, TCant hereafter, is northward, with a mean value of 254±29 kmols-1 over the 1997-2010 period. The TCant presents a high interannual variability, masking any trend different from 0 for this period. In order to understand the mechanisms controlling the variability of the TCant across the SPNA, we propose a new method that quantifies the transport of Cant caused by the diapycnal and isopycnal circulation. The diapycnal component yields a large northward transport of Cant (400±29 kmols-1) which is partially compensated by a southward transport of Cant caused by the isopycnal component (-171±11 kmols-1), mainly localized in the Irminger Sea. Most importantly, the diapycnal component is found to be the main driver of the variability of the TCant across the SPNA. Both the Meridional Overturning Circulation (MOC) and the Cant increase in the water column have an important effect on the variability of the diapycnal component and of the TCant itself. Based on this analysis, we propose a simplified estimator for the variability of the TCant based on the intensity of the MOC and on the difference of Cant between the upper and lower limb of the MOC (ΔCant). This estimator shows a good consistency with the diapycnal component of the TCant, and help to disentangle the effect of the variability of both the circulation and the Cant increase on the TCant variability. We find that ΔCant keeps increasing over the past decade, and it is very likely that the continuous Cant increase in the water masses will cause an increase in the TCant across the SPNA at long time scale. Nevertheless, at the time scale analyzed here (1997-2010), the MOC is controlling the TCant variability, blurring the expected TCant increase. Extrapolating the observed ÄCant increase rate and considering the predicted slow-down of 25% of the MOC, the TCant across the SPNA is expected to increase by 430 kmols-1 during the 21st century. Consequently, an increase in the storage rate of Cant in the SPNA could be envisaged. [ABSTRACT FROM AUTHOR]

In response to the need for improving our understanding of the evolution and the interannual variability of the winter Arctic stratosphere, in January 2009 a ground-based millimeter-wave spectrometer (GBMS) was installed at the Network for the Detection of Atmospheric Composition Change (NDACC) site in Thule (76.5° N, 68.8° 5 W), Greenland. In this work, stratospheric GBMS O3 and HNO3 vertical profiles obtained from Thule during winters 2010 (HNO3 only), 2011 and 2012 are characterized and intercompared with co-located Aura MLS measurements. Using a recently developed algorithm based on Optimal Estimation, we find that the GBMS O3 retrievals show good 10 sensitivity (>80%) to atmospheric variations between ∼17 and ∼50 km, where their 1 σ uncertainty is estimated to be the larger of ∼11% or 0.2 ppmv. Similarly, HNO3 profiles can be considered for scientific use between ∼17 and ∼45 km altitude, with a 1 σ uncertainty that amounts to the larger of 15% or 0.2 ppbv. Comparisons with Aura MLS version 3.3 observations show that, on average, GBMS O3 mixing ratios are 15 biased low with respect to MLS throughout the stratosphere, with differences ranging between ∼0.3 ppmv (8 %) and 0.9 ppmv (18 %) in the 17-50 km vertical range. GBMS HNO3 values display instead a high bias with respect to MLS up to 26 km, reaching a maximum of ∼1 ppbv (10 %) near the mixing ratio profile peak. O3 and HNO3 values from the two data sets prove to be well correlated at all altitudes, although their corre20 lations worsen at the lower end of the altitude ranges considered. Column contents of GBMS and MLS O3 (from 20 km upwards) and HNO3 (from 17 km upwards) correlate very well and indicate that GBMS measurements can provide valuable estimates of column interannual and seasonal variations for these compounds. [ABSTRACT FROM AUTHOR]

Reconstructions of past atmospheric methane concentrations are available from ice cores from both, Greenland and Antarctica. The difference observed between the two polar methane concentration levels is a valuable additional parameter which allows to constrain the geographical location of the responsible methane sources. Here we present new high-resolution methane records from the North Greenland Ice Core Project (NGRIP) and the European Project for Ice Coring in Antarctica (EPICA) Dronning Maud Land (EDML) ice cores covering Termination 1, the Last Glacial Maximum, and parts of the last glacial back to 32 000 years before present. Due to the highresolution records the synchronisation between the ice cores from NGRIP and EDML is considerably improved and the interpolar concentration difference of methane is determined with unprecedented precision and temporal resolution. Relative to the mean methane concentration, we find a rather stable positive interpolar difference throughout the record with its minimum value of 3.7±0.7% between 21 900-21 200 years before present, which is higher than previously estimated in this interval close to the Last Glacial Maximum. This implies that Northern Hemisphere boreal wetland sources were never completely shut off during the peak glacial. Starting at 21 000 years before present, i.e. severval millenia prior to the transition into the Holocene, the relative interpolar difference becomes even more positive and stays at a fairly stable level of 6.5±0.8% during Termination 1. We hypothesise that the anti-correlation observed in the monsoon records from the Northern and Southern Hemispheres induces a methane source redistribution within lower latitudes, which could explain parts of the variations in the interpolar difference. [ABSTRACT FROM AUTHOR]

Presents comments on the paper "Pollen Transport to Southern Greenland: New Evidences of a Late Spring Long Distance Transport," by D.-D. Rousseau et al, which appeared in the 2005 issue of "Biogeosciences Discussions." Scientific content and novelty of the paper; Assumption on the necessity of upward vertical motion of the air; Impact of the gravitational settling on particles.

This exploratory study presents Greenland as a case of a peripheral destination that complicates and contradicts global definitions of sustainable tourism. Using empirical data that consists of 39 semi-structured interviews, the author employs an inductive approach to discuss the conceptualisation of sustainable tourism according to local stakeholders in Greenland. The key points of conflict surrounding sustainable tourism in Greenland are identified and discussed, with a focus on how local stakeholders contradict each other, and on how the debates prevalent at the local scale can inform tourism development in other peripheral places. The paper contributes to academic literature by offering a deeper understanding of how core-periphery dynamics can influence perceptions of and priorities for sustainable tourism in peripheral places. It benefits the industry by exposing the main debates around the issue of sustainable tourism in Greenland, which can be used to inform the nation's tourism development. [ABSTRACT FROM AUTHOR]

In this study we report diapycnal diffusive fluxes of dissolved iron (dFe), dissolved aluminium (dAl) and the major macronutrients to the surface waters of the North Atlantic subpolar gyre. Turbulent diffusivities at the base of the summer mixed layer ranged from 0.01-0.5 (median 0.07) cm² s-1 and daily macronutrient fluxes into the surface mixed layer typically represented < 0.5% of integrated mixed layer inventories, although fluxes were highly variable. Elevated nutrient fluxes of up to 4% of mixed layer inventories were identified on the Greenland Shelf where integrated nutrient pools were lowest due to localised shoaling of the mixed layer. Diffusive fluxes of dFe and dAl were typically < 0.1% of mixed layer inventories but were also highly variable between stations. Approximations of daily phytoplankton nutrient and Fe uptake indicate that the diffusive flux may at best represent < 10% of phytoplankton macronutrient uptake, and only 1% of daily phytoplankton Fe uptake. The daily turbulent diffusive flux of dFe was comparable in magnitude to coincident estimates of aeolian Fe supply but despite shallower than normal convective mixing in winter 2010 the diffusive supply was 22 to 59 times smaller than the annual convective supply of Fe to the Irminger and Iceland basins respectively. The general picture obtained from this study is one of small magnitude diffusive nutrient and Fe fluxes to the subpolar North Atlantic during the period of annual nutrient minima and indicates that the diffusive supply mechanism is unlikely to alleviate the recently identified presence of seasonal iron limitation within the North Atlantic subpolar gyre; a condition exacerbated by low dFe :NO3- ratios in subsurface source waters. [ABSTRACT FROM AUTHOR]

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The article reports on the research project related to climate change in Greenland conducted by researchers Ian Harding and James Eldrett. In their study, they were able to gather evidences which are useful in constructing the climatic conditions during the Eocene-Oligocene transition in Greenland. They admit the research allows them to capitalize on the pollen fossil record to track changes in vegetation and even climate changes.

The article discusses how a scientific program, which was part of the 2007 International Polar Year, helped to advance the study by a group of researchers. Topics include how the extension of the program benefited methane emissions research by Torben Christensen and his colleagues on the Greenland tundra, an explanation of the International Polar Year, and a description of methane, which is a greenhouse gas, and its effects on the environment.

Background: To strengthen palliative care for children in the Nordic countries, an updated status of current needs, resources, clinical services, education, and research is necessary to align and consolidate future research. A Nordic research collaboration initiative for children with palliative care needs was assembled in 2023. Building on this initiative, this paper presents an overview of pediatric palliative care (PPC) in the Nordic countries' (a) population characteristics, (b) care models and setting of care, (c) education and training, and (d) research. Methods: The Nordic initiative researchers collaboratively gathered and assessed available data on the characteristics of PPC within Denmark, Finland, Greenland, Iceland, Norway, the Faroe Islands, Sweden, and Åland. Data were compiled in a matrix with population characteristics, models- and setting of care, education and training, and areas of research in a Nordic context. The findings are narratively and descriptively presented, providing an overview of Nordic PPC. Results: In total, the Nordic child population comprises around six million children (0–19 years), of which about 41.200 are estimated to be living with a life-limiting and/or life-threatening condition. Healthcare services are provided through various care models, ranging from specialized care to homecare settings. Overall, there remain few opportunities for education and training with some exceptions. Also, Nordic research within PPC has been shown to be a growing field although much remains to be done. Conclusion: This overview is the first outline of the current PPC in Nordic countries. Although some differences remain important to acknowledge, overall, the strengths and challenges faced within PPC in the Nordic countries are comparable and call for joint action to increase evidence, services, and education to better serve the children, families, and healthcare personnel within PPC. Despite the varying structural premises for PPC, research endeavors aiming to provide evidence in this field seem increasing, timely and relevant for the Nordic countries, as well as the international context. [ABSTRACT FROM AUTHOR]

The freshwater discharge from melting ice sheets in the deglaciation or glaciation is prone to anomalies in ocean-atmosphere transport between different latitudes, which can lead to a series of abrupt millennial-scale climate events, either obvious or not, such as the Younger Dryas (YD) events and YD-like events. Marine Isotope Stage 11c (MIS 11c) serves as one of the best references for the current Holocene, and the studies of possible YD-like events and their triggering mechanisms during Holocene are conducive to the understanding of the occurrence pattern of extreme climate events. In this paper, the results of the study on the J33 δ18O sequence records of stalagmites in Jinfo Cave, Chongqing, are shown: (1) Stalagmites in the Asian monsoon climate zone reveal a millennial-scale weak monsoon event that occurred around 410 ka BP prior to the Glacial Maximum of MIS 11 interglacial period. (2) Both the 410 ka weak monsoon event and the YD event occurred during the gradual strengthening of the monsoon and ascending branch of summer insolation in the Northern Hemisphere prior to the Glacial Maximum of interglacial period. This was also a time when Atlantic Meridional Overturning Circulation (AMOC) disturbance occurred. The duration, internal structure, and pattern of the events were similar, with differences in the change magnitude and ice volume conditions. (3) The weak monsoon event that occurred in 410 ka BP was primarily influenced by the combined effects of insolation and AMOC. This event was characterized by a sustained warming process that accelerated the melting of the Greenland ice sheet, leading to the destabilization of this ice sheet. The continuous flowing of freshwater into the North Atlantic resulted in a short-lived AMOC oscillation. The weakening of the AMOC resulted in a cold anomaly over the North Atlantic. As a result of atmospheric telecorrelation, the weaker AMOC led to a weaker Asian Summer Monsoon (ASM). [ABSTRACT FROM AUTHOR]

Ice fractures when subject to stress that exceeds the material failure strength. Previous studies have found that a von Mises failure criterion, which places a bound on the second invariant of the deviatoric stress tensor, is consistent with empirical data. Other studies have suggested that a scaling effect exists, such that larger sample specimens have a substantially lower failure strength, implying that estimating material strength from laboratory-scale experiments may be insufficient for glacier-scale modeling. In this paper, we analyze the stress conditions in crevasse onset regions to better understand the failure criterion and strength relevant for large-scale modeling. The local deviatoric stress is inferred using surface velocities and reanalysis temperatures, and crevasse onset regions are extracted from a remotely sensed crevasse density map. We project the stress state onto the failure plane spanned by Haigh–Westergaard coordinates, showing how failure depends on mode of stress. We find that existing crevasse data are consistent with a Schmidt–Ishlinsky failure criterion that places a bound on the absolute value of the maximal principal deviatoric stress, estimated to be 158±44 kPa. Although the traditional von Mises failure criterion also provides an adequate fit to the data with a von Mises strength of 265±73 kPa, it depends only on stress magnitude and is indifferent to the specific stress state, unlike Schmidt–Ishlinsky failure which has a larger shear failure strength compared to tensile strength. Implications for large-scale ice flow and fracture modeling are discussed. [ABSTRACT FROM AUTHOR]

In 1925, Silas Sandgreen sent a map to the Library of Congress in Washington, D.C. Instead of ink on paper, Sandgreen's map featured strands of sinew binding painted driftwood islands to an animal hide, articulating the islands Kitsissut and Imerissoq of Disko Bay off the western shore of Kalaallit Nunaat. In the near century since its completion, the map's materials have become indexical of their maker's Indigeneity, functioning as erroneous evidence of "authentic" Inuit cartographic practices. A repeated fetishizing of alterity has divorced the object from its original conditions of creation, obscuring its origins and cultural meanings. This paper seeks to restore the historicity of Silas Sandgreen's map by taking a new approach to its materiality. Taking cue from recent scholarship that frames the map as an artwork, we locate the object at the intersection of various social, political, and environmental ideologies sweeping Kalaallit Nunaat, and Sandgreen's particular home islands, in the 1920s. In order to do so, we restore the maker's biography composed from new findings in Indigenous-language archives, and juxtapose that biography alongside a visual and material analysis of the most prominent media of the map: sealskin and driftwood. By charting these material histories alongside social and ecological ones, we aim to provide a template that advances multiple interdisciplinary methodologies in the nascent field of Arctic art history. [ABSTRACT FROM AUTHOR]

The article presents a study which evaluates the flux gradient technique for measuring turbulent ozone flux at the Summit research camp in Greenland. A Monte Carlo statistical approach has been used to analyze the ozone exchange measurements. Several measuring instruments utilized in the study are highlighted which include ultraviolet absorption analyzers, aspirate thermocouple sensors and cup anemometers.

Twenty years of gravity observations from various satellite missions have provided unique data about mass redistribution processes in the Earth system, such as melting of Greenland's ice shields, sea level changes, ground and underground water depletion, droughts, floods, etc. The ongoing climate change underlines the urgent need to continue this kind of observations with future gravimetry missions using enhanced concepts and sensors. This paper studies the benefit of enhanced electrostatic and novel optical accelerometers and gradiometers for future gravimetry missions. One of the limiting factors in the current space gravimetry missions is the drift of the Electrostatic Accelerometers (EA) which dominates the error contribution at low frequencies (<1mHz). This study focuses on the modeling of enhanced EAs with laser-interferometric readout, so-called optical accelerometers, and on evaluating their performance for gravity field recovery in future satellite missions. In this paper, we simulate gravimetry missions in multiple scopes, applying various software modules for satellite dynamics integration, accelerometer (ACC) and gradiometer simulation and gravity field recovery. The total noise budgets of the modeled enhanced electrostatic and optical ACCs show a similar sensitivity as the ACC concepts from other research groups. Parametrization w.r.t. the weight of the test mass (TM) of ACCs and the gap between the TM and the surrounding electrode housing confirmed the fact known from previous results that an ACC with a heavier TM and a larger gap will perform better. Our results suggest that the anticipated gain of novel ACCs might at some point be potentially limited by noise from the inter-satellite laser ranging interferometry. In order to present the advantage of the novel sensors, time-variable background models and associated aliasing errors were not considered in our simulations. The utilization of enhanced EAs and optical ACCs shows a significant improvement of accuracy compared to the currently used GRACE-like EA. In addition, their benefit in double satellite pairs in a so-called Bender constellation as well as in the combination of low-low satellite-to-satellite tracking with cross-track gradiometry has been investigated. [ABSTRACT FROM AUTHOR]

In an iceberg-choked fjord, meltwater can drive circulation. Down-fjord of the ice, buoyancy and rotation lead to an outflowing surface coastal current hugging one side of the fjord with an inflowing counter-current below. To predict the structure and evolution of these currents, we develop an analytical model – complemented by numerical simulations – that involves a rectangular fjord initially at rest. Specifically, we (i) start with the so-called Rossby adjustment problem; (ii) reconfigure it for a closed channel with stratification; and (iii) generalize the conventional "dam-break" scenario to a gradual-release one that mimics the continual, slow injection of meltwater. Implicit in this description is the result that circulation is mediated by internal Kelvin waves. The analytical model shows that if the total meltwater flux increases (e.g., a larger mélange, warmer water, or enhanced ice–ocean turbulence) then circulation strength increases as would be expected. For realistic parameters, a given meltwater flux induces an exchange flow that is ∼ 50 times larger. This factor decreases with increasing water column stratification and vice versa. Overall, this paper is a step toward making Greenland-wide predictions of fjord inflows and outflows induced by icebergs. [ABSTRACT FROM AUTHOR]

Polar regions and Greenland in particular are highly sensitive to global warming. Impacts on Greenland's glaciers may be observed through the increasing number of calving events. However, a direct assessment of the calving activity is limited due to the remoteness of polar regions and the cloudy weather which makes impossible a recurrent observation through satellite imagery. To tackle this issue, we exploit the seismological network deployed in Greenland which actively records seismic signals associated with calving events, hereinafter referred to as glacial earthquakes. These seismic signals present a broad frequency range and a wide diversity of waveform which make them difficult to discriminate from tectonic events as well as anthropogenic and natural noises. In this study, we start from two catalogues of known events, one for glacial earthquake events which occurred between 1993 and 2013 and one for earthquakes which occurred in the same time period, and we implement a detection algorithm based on the STA/LTA method to extract signals' events from continuous data. Then, we train and test a machine learning processing chain based on the Random Forest algorithm which allows us to automatically associate the events respectively with calving and tectonic activity, with a certain probability. Finally, we investigate 844 selected days spanning time of continuous data from the Greenland regional seismic network which results in a new, more exhaustive, catalogue of glacial earthquakes expanded of 1633 newly detected glacial events. Moreover, we extensively discuss the choice of the features used to describe glacial earthquakes, in particular the 39 new features created in this study which have drastically improved our results with 7 of the 10 best features being in the added set. The perspective of further expansion of the glacial earthquake catalogue applying the processing chain discussed in this paper on different time spans highlights how combining seismology and machine learning can increase our understanding of the spatio-temporal evolution of calving activity in remote regions. [ABSTRACT FROM AUTHOR]

The Green's function approach is well‐established and widely used for modeling the surface mass loading displacements. Global mean Green's functions (MGFs) are commonly applied without considering local variations of the crustal structure. Derived from the modified layered Earth structure, the local Green's functions (LGFs) are theoretically beneficial to generate more accurate deformation, since they consider interior information of the local crust. This paper analyzed the differences among MGFs from Gutenberg–Bullen A model and two sets of LGFs derived from modified PREM Earth models consolidating with two crust models TEA12 and CRUST1.0, hereafter called PREMTEA and PREMCRU, respectively. Utilizing MGFs and two sets of LGFs, we modeled the corresponding 3D atmospheric loading displacements for 984 ITRF2014 stations and compared them with the ITRF2014 residuals. The results show that LGFs from PREMTEA and PREMCRU perform well in further promoting scatter reduction for ∼72%, ∼56%, and ∼85% of stations for the Up, East and North components, respectively. The improvements for the North components are significant (up to 3.6%). In particular, stations in the east coastal areas of North America and the west edge of Greenland exhibit further promoting scatter reduction for the East components (up to ∼2.5%), while those located in west coastline of North America show better performance for the North components. Nevertheless, there are significant anomalies in northern Europe for PREMCRU, the mutation margin of which should be carefully considered when using a resolution higher than 1°. In the area around station MORP (358.31°W, 55.21°N, sited at coastline of Britain), we suggest using PREMTEA model. Plain Language Summary: In any location worldwide, we employ a consistent set of numbers, known as load Green's functions that characterize the elastic properties of the Earth, to model the deformation caused by mass transfer on Earth's surface, which is referred to as surface mass loading effects. Most research and data products adopt same set of global mean Green's functions for any location on Earth, which neglects the differences in elastic properties of various regions of the Earth, leading to modeling errors to some extent. This study aims to optimize the modeling using local load Green's functions, with the objective of obtaining results that are more theoretically valuable. "Local" means that the Green's functions for each site are derived from an Earth model that takes into account the local crustal structure. The modeled atmospheric loading displacements exhibit enhanced alignment with GNSS position time series. This, in turn, further elucidates that deformations can be more attributed to atmospheric loading. Moreover, the model shows improved performance in the horizontal components when compared to the vertical components. Key Points: Local load Green's Functions enable a more precise modeling of loading displacements than global mean Green's FunctionsThe modeled atmospheric loading displacements based on Local Green's Functions can improve scatter reduction of GNSS position time seriesTwo sets of local load Green's Functions, based on CRUST1.0 model and TEA12 model, are compared. We recommend TEA12 for European region [ABSTRACT FROM AUTHOR]

Numerical modeling of ice sheet motion and hence projections of global sea level rise require information about the evolving subglacial environment, which unfortunately remains largely unknown due to its difficulty of access. Here we advance such subglacial observations by reporting multi‐year observations of seismic tremor likely associated with glacier sliding at Helheim Glacier. This association is confirmed by correlation analysis between tremor power and multiple environmental forcings on different timescales. Variations of the observed tremor power indicate that different factors affect glacial sliding on different timescales. Effective pressure may control glacial sliding on long (seasonal/annual) timescales, while tidal forcing modulates the sliding rate and tremor power on short (hourly/daily) timescales. Polarization results suggest that the tremor source comes from an upstream subglacial ridge. This observation provides insights on how different factors should be included in ice sheet modeling and how their timescales of variability play an essential role. Plain Language Summary: The Greenland Ice Sheet has lost ice increasingly in the past few decades, contributing significantly to global sea level rise. However, large uncertainties remain in computer simulations of such ice mass loss and hence sea level rise. This uncertainly is mainly attributed to the lack of information on what is happening at the bottom of the ice sheet and how that affects ice sheet movement. For example, how much water is there and whether it is in isolated pockets or is well distributed as a thin sheet can have an important effect on ice movement. In this paper, we observe small ground motions that are generated during glacier movement at a marine‐terminating glacier in Greenland. By analyzing the energy variation of the small ground motions over multiple years as well as observing the reasons that cause the variations, we learn that subglacial water pressure may control ice flow speeds on a seasonal/annual scale, and that ocean tides can change ice flow on an hourly/daily scale. This observation provides important constraints for computer simulations of future sea level rise in terms of the impacting factors and their respective timescales. Key Points: Multi‐year seismic records reveal glacial slip and tremor variability at Helheim GlacierTremor correlates with high effective pressure at tidal timescales, opposite to the expectation at longer timescalesThe tremor source points to an upstream subglacial ridge [ABSTRACT FROM AUTHOR]