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Grigoriev ice cap, located in the Tien Shan mountains of Kyrgyzstan, has a rich history of firn and ice core drilling starting as early as 1962. Here we extend the exceptional record and describe an 18 m firn core, drilled in February 2018 on the summit of Grigoriev ice cap, at 4600 m a.s.l. The core has been analyzed for firn stratigraphy, major ions, black carbon, water stable isotope ratios and total β activity. We find that the core covers 46±3 years and overlaps by 2 to 3 decades with legacy cores. A good agreement is found in major ion concentrations for the overlapping period. Concentrations of black carbon and major ions are reduced since the early 2000s, indicating the onset of meltwater runoff. Nevertheless, general concentration trends of these species are consistent with observations and Central Asian ice core records, since emissions were highest during periods when melt influence was negligible. The record of water stable isotopes does not reflect the strong increase of air temperatures during the last decades, implying that water stable isotope ratios ceased to be proxies of temperature variations at this site. Apart from runoff evidence, however, the firn's thermal regime appears remarkably unchanged. Firn temperatures in 2018 were the highest on record (∼-1.6 °C at ∼17 m depth). However, temperatures in 2023 are again similar to the early 2000s at ∼-2.5 °C. Furthermore, we find little change in net accumulation since the 1980s. We hypothesize (i) that firn temperatures are stabilized by the removal of latent heat through lateral meltwater runoff, and (ii) that mass loss by runoff is compensated by an increase in accumulation. Data from a nearby weather station support the latter hypothesis. [ABSTRACT FROM AUTHOR]

To reconstruct the history of organic carbon (OC) aerosol over south‐eastern Europe, dissolved organic carbon (DOC) and its 14C signature (DO14C) were investigated along an ice core drilled at the Mount Elbrus (ELB) in Caucasus. In summer, compared to pre‐1945 levels, the DOC concentrations increased by 45% after 1960, the mean DO14C depletion in recent ELB ice relative to atmospheric 14CO2 of 32% being attributed to fossil‐fuel sources. DO14C content of ice deposited during the bomb‐peak era (1955–1980) closely followed atmospheric 14CO2 changes caused by atmospheric nuclear tests, suggesting the living biosphere as the main biogenic source of DOC in summer in this region. ELB data contrast with those previously obtained in summer Alpine (western Europe) ice in which a post‐1950 doubling of DOC was observed and attributed to enhanced emissions of organic compounds from vegetation in France. This regional difference is discussed with respect to changes of biogenic organic compound emissions in response to past change of use‐land and global warming. ELB data document, for the first time, changes of DOC and DO14C in winter mountain ice showing an increase by 44% of DOC levels associated with a 14C signature being 47% lower than that of atmospheric 14CO2 in ELB ice deposited after 1960. The 14C winter ELB ice record followed atmospheric 14CO2 changes with a delay of ∼3 years, suggesting that remaining emissions from the living biosphere, together with a small contribution from wood burning, are the main biogenic sources of DOC in winter in this region. Plain Language Summary: A good knowledge of past aerosol load and composition is important for climate change. In addition to sulfate, organic carbon aerosol (OC) is a major constituent of present‐day aerosol but its budget remains far less understood. Ice‐core chemical studies help to quantify natural versus anthropogenic sources over the past. Previous investigations of OC and its radiocarbon signature in Alpine ice had shown a doubling of summer OC due to enhanced emissions from vegetation contrasting with a weak impact of fossil‐fuel emissions in western Europe. The regional character of biogenic emissions motivated, however, further studies conducted in other regions. Investigations of OC and its radiocarbon signature in an ice core extracted in the Caucasus permitted to reconstruct past OC changes in the south‐eastern Europe. It is shown that, even in 1970, vegetation emissions still dominate fossil‐fuel emissions as source of OC in summer. A quite large temporal variability of OC is observed and attributed to variations of vegetation emissions in response to past fluctuations of summer temperature in this region. After 1960, fossil‐fuel emissions in winter became almost as large as biogenic emissions that were related to the living biosphere with a small contribution from wood burning at that season. Key Points: Biogenic sources dominate fossil‐fuel sources of present‐day summer organic carbon aerosol (70% vs. 30%) in south‐eastern EuropeLarge pre‐industrial variability of organic carbon aerosol in summer driven by vegetation emissions modulated by past temperaturesLiving biosphere with a small contribution from wood burning slightly exceeds present‐day fossil‐fuel sources of organic carbon in winter [ABSTRACT FROM AUTHOR]

In this study, we present a seasonally resolved accumulation record spanning from 1750 to 2009 Common Era (CE), based on a 181.8 m ice core obtained from the Elbrus Western Plateau in the Caucasus. We implemented various methods to account for uncertainties associated with glacier flow, layer thinning, and dating. Additionally, we applied a novel approach to calculate a seasonal calendar for meteorological data, enabling comparison with ice core records. The reconstructed accumulation data were compared with available meteorological data, gridded precipitation records, and paleo-reanalysis data. Reconstructed accumulation is representative for a large region south of the Eastern European plain and Black Sea region with summer precipitation being the primary driver of precipitation variability. We identified a statistically significant relationship between changes in regional precipitation and fluctuations in the North Atlantic Oscillation (NAO) index, which is, however, not stable over the entire period covered by the ice core. [ABSTRACT FROM AUTHOR]

Grigoriev Ice Cap, located in the Tien Shan mountains of Kyrgyzstan, has a rich history of firn and ice core drilling starting as early as 1962. Until now, the time series ended with a core drilled in 2007. Here we extend the exceptional record and describe an 18 m firn core, drilled in February 2018 on the summit of Grigoriev Ice Cap, at 4600 m a.s.l. The core has been analyzed for firn stratigraphy, major ions, black carbon, water stable isotope ratios and total β -activity. We find that the core covers 46±3 years and overlaps by two to three decades with legacy cores. A good agreement is found in major ion concentrations for the overlapping period. Concentration in ions, susceptible to being washed out, is reduced since the early 2000s. This indicates the onset of meltwater runoff. Apart from runoff evidence, however, the firn appears remarkably unchanged. We find little change in net accumulation since the 1980s. Firn temperatures fluctuate, with 2018 temperatures being the highest on record 1.6 °C at 17 m depth). However, temperatures in 2023 are again similar to the early 2000s at 2.5 °C. We hypothesize (i) that firn temperatures are stabilized by the removal of latent heat through lateral meltwater runoff, and (ii) that mass loss by runoff is compensated by an increase in snowfall. While data from a nearby weather station support the latter hypothesis, thorough testing of both hypotheses will require surface mass balance and firn modelling. [ABSTRACT FROM AUTHOR]

In this study, we present a seasonal-resolution accumulation record spanning the period from 1750 to 2009 Common Era (CE), based on a 181.8-m ice core obtained from the Elbrus Western Plateau in the Caucasus. We implemented various methods to account for uncertainties associated with glacier flow, layer thinning, and dating. Additionally, we developed a novel approach to calculate a seasonal calendar for meteorological data, enabling comparison with ice core records. The reconstructed accumulation data were compared with available meteorological data, gridded precipitation records, and paleo reanalysis data. Reconstructed accumulation is representative for a large region south of Eastern European plain and Black sea region. Summer precipitation was found to be the primary driver of precipitation variability. We identified a statistically significant but unstable in time relationship between changes in precipitation in the region and fluctuations of the North Atlantic Oscillation (NAO) index. [ABSTRACT FROM AUTHOR]

This study reports on the glaciochemistry of a deep ice core (182 m long) drilled in 2009 at Mount Elbrus (43°21′ N, 42°26′ E; 5115 m above sea level) in the Caucasus, Russia. Radiocarbon dating of the particulate organic carbon fraction in the ice suggests a basal ice age of ~ 1670 ± 400 cal yr BP. Based on chemical stratigraphy, the upper 168.6 m of the core were dated by counting annual layers. The seasonally resolved chemical records cover the years 1774–2009 (Common Era), thus, being useful to reconstruct many aspects of atmospheric pollution in central Europe from pre-industrial times to present-day. After having examined the extent to which the arrival of large dust plumes originating from Sahara and Middle East modifies the chemical composition of the Elbrus (ELB) snow and ice layers, we focus on the sulfur pollution. The ELB sulfate levels indicate a four- and six-fold increase from 1774–1900 to 1980–1995 in winter and summer, respectively. Remaining close to 116 ± 28 ppb during the nineteen century, the summer sulfate levels started to rise at a mean rate of ~ 6 ppb per year from 1920 to 1950. The summer sulfate increase accelerated between 1950 and 1975 (11 ppb per year), levels reaching a maximum between 1980 and 1990 (730 ± 152 ppb) and subsequently decreasing to 630 ± 130 ppb at the beginning of the twenty first century. Long-term sulfate trends observed in the ELB ice cores are compared with those previously obtained in Alpine ice, the most important difference consists in a more pronounced decrease of the sulfur pollution over the three last decades in western than central Europe. [ABSTRACT FROM AUTHOR]

Ice cores are one of the most valuable paleo-archives. Records from the ice cores can provide information not only about the amount of dust in the atmosphere but also about dust sources and its changes in the past. A 182m long ice core has been recovered at the western plateau of Mt. Elbrus (5115m elevation) in 2009. This record was extended with the shallow ice core drilling in 2013. Here we present analysis of the concentrations of Ca2+, a commonly used proxy of dust, recorded in Elbrus ice core over the period 1774-2013. The calcium record reveals a quasi decadal variability with a general increasing trend. Using multiple regression analysis we found a statistically significant spatial correlation of the Elbrus Ca2+ summer concentrations and precipitation and soil moisture content in Levant region (specifically Syria and Iraq). The Ca2+ record also correlates with drought index in North Africa (r=0.69 p<0.001) and Middle East regions (r=0.71p<0.001). There is a prominent increase in dust concentration in the ice core over the past 200 years which confirms that the recent droughts in Fertile Crescent 1998-2012 period were most severe at least for the past two centuries. For the 33 years (1979-2012), the significant correlations were found between the Ca2+ and Pacific circulation indexes (PDO, SOI and Niño 4) which may indicate that due to increase in frequency of extreme El Niño and La Niña events with climate warming the influence of circulation over the Pacific Ocean extended to the Middle East. [ABSTRACT FROM AUTHOR]

Black carbon (BC), emitted by fossil fuel combustion and biomass burning, is the second largest manmade contributor to global warming after carbon dioxide (Bond et al., 2013). However, limited information exists on its past emissions and atmospheric variability. In this study, we present the first high-resolution record of refractory BC (rBC, including mass concentration and size) reconstructed from ice cores drilled at a high-altitude eastern European site in Mt. Elbrus (ELB), Caucasus (5115ma.s.l.). The ELB ice core record, covering the period 1825-2013, reflects the atmospheric load of rBC particles at the ELB site transported from the European continent with a larger rBC input from sources located in the eastern part of Europe. In the first half of the 20th century, European anthropogenic emissions resulted in a 1.5-fold increase in the ice core rBC mass concentrations with respect to its level in the preindustrial era (before 1850). The summer (winter) rBC mass concentrations increased 5-fold (3.3-fold) in 1960-1980, followed by a decrease until ~2000. Over the last decade, the rBC signal for summertime slightly increased.We have compared the signal with the atmospheric BC load simulated using past BC emissions (ACCMIP and MACCity inventories) and taken into account the contribution of different geographical regions to rBC distribution and deposition at the ELB site. Interestingly, the observed rBC variability in the ELB ice core record since the 1960s is not in perfect agreement with the simulated atmospheric BC load. Similar features between the ice core rBC record and the best scenarios for the atmospheric BC load support anthropogenic BC increase in the 20th century being reflected in the ELB ice core record. However, the peak in BC mass concentration observed in ~1970 in the ice core is estimated to occur a decade later from past inventories. BC emission inventories for the period 1960s-1970s may be underestimating European anthropogenic emissions. Furthermore, for summertime snow layers of the 2000s, the slightly increasing trend of rBC deposition likely reflects recent changes in anthropogenic and biomass burning BC emissions in the eastern part of Europe. Our study highlights that the past changes in BC emissions of eastern Europe need to be considered in assessing ongoing air quality regulation. [ABSTRACT FROM AUTHOR]

Black carbon (BC), emitted by fossil fuel combustion and biomass burning, is the second largest man-made contributor to global warming after carbon dioxide (Bond et al., 2013). However, limited information exists on its past emissions and atmospheric variability. In this study, we present the first high-resolution record of refractory BC (rBC, including mass concentration and size) reconstructed from ice cores drilled at a high-altitude Eastern European site in Mt. Elbrus (ELB), Caucasus (5115 m a.s.l.). The ELB ice core record, covering the period 1825-2013, reflects the atmospheric load of rBC particles at the ELB site transported from the European continent with a larger rBC input from sources located in the Eastern part of Europe. In the first half of the 20th century, European anthropogenic emissions resulted in a 1.5-fold increase in the ice core rBC mass concentrations as respect to its level in the preindustrial era (before 1850). The rBC mass concentrations increased by a 5-fold in 1960-1980, followed by a decrease until ~ 2000. Over the last decade, the rBC signal for summer time slightly increased. We have compared the signal with the atmospheric BC load simulated using past BC emissions (ACCMIP and MACCity inventories) and taken into account the contribution of different geographical region to rBC distribution and deposition at the ELB site. Interestingly, the observed rBC variability in the ELB ice core record since the 1960s is not in perfect agreement with the simulated atmospheric BC load. Similar features between the ice core rBC record and the best scenarios for the atmospheric BC load support that anthropogenic BC increase in the 20th century is reflected in the ELB ice core record. However, the peak in BC mass concentration observed in ~ 1970 in the ice core is estimated to occur a decade later from past inventories. BC emission inventories for the period 1960s-1970s may be underestimating European anthropogenic emissions. Furthermore, for summer time snow layers of the last 2000s, the slightly increasing trend of rBC deposition likely reflects recent changes in anthropogenic and biomass burning BC emissions in the Eastern part of Europe. Our study highlights that the past changes in BC emissions of Eastern Europe need to be considered in assessing on-going air quality regulation. [ABSTRACT FROM AUTHOR]

A 181.2&m ice core was recovered from a borehole drilled into bedrock on the western plateau of Mt. Elbrus (43°20'53.9''&N, 42°25'36.0''&E; 5115&m&a.s.l.) in the Caucasus, Russia, in 2009 (Mikhalenko et al., 2015). Here, we report on the results of the water stable isotope composition from this ice core in comparison with results from shallow ice cores. There is a distinct seasonal cycle of the isotopic composition which allowed dating by annual layer counting. Dating has been performed for the upper 126&m of the deep core combined with shallow cores data. The whole record covers one century from 2013 back to 1914. Due to the high accumulation rate (1380&mm w.e. per year) and limited melting we obtained the isotopic composition and accumulation rate records with seasonal resolution. These values were compared with available meteorological data from 13 weather stations in the region, and also with atmosphere circulation indices, back-trajectories calculations and GNIP data in order to decipher the drivers of accumulation and ice core isotopic composition in the Caucasus region. In the summer season the isotopic composition depends on the local temperature, while in winter, the atmospheric circulation is the predominant driver of the ice core isotopic composition. The snow accumulation rate correlates well with the precipitation rate in the region all year round, this made it possible to reconstruct and expand the precipitation record at the Caucasus highlands from 1914 till 1966 when the reliable meteorological observations of precipitation at high elevation began. [ABSTRACT FROM AUTHOR]

Here we present the results of isotopic investigations of several ice cores obtained in the Caucasus Mountains insouthern Russia, Mount Elbrus and Mount Kazbek. There is a distinct seasonal cycle in the isotopic compositionrecord of these cores. We discuss the isotopic composition of the Elbrus deep ice core (182 m) obtained in 2009 aswell as several shallow cores obtained in 2012 and 2013. The cores were dated using annual layers counting. Wepresent the data covering the period from 1816 till 2013.These values were compared with available meteorological records from 13 weather stations in the region, andalso with atmosphere circulation characteristics, back-trajectories calculations and GNIP data. We worked outthe possible mechanisms of the formation of the isotopic composition of precipitation and of ice deposits in theCaucasus region.It was shown that in the summer season, the isotopic composition depends on the local temperature, whilein winter, it depends on the atmospheric circulation. The snow accumulation rate correlates well with theprecipitation rate in the region all year round. We reconstructed the summer temperature and precipitation recordsat the Caucasus highlands from 1816 till 1930 when the meteorological observations at high elevation began.The research is supported by Russian Science Foundation grant 17-17-01270. This work was also conducted in theframe of the International Associated Laboratory (LIA) "Climate and Environments from Ice Archives" linkingseveral Russian and French laboratories and institutes, and with additional support from the French embassy inRussia. [ABSTRACT FROM AUTHOR]