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Black carbon (BC) deposited on snow and glacier surfaces can reduce albedo and lead to accelerated melt. An ice core recovered from Guoqu glacier on Mt. Geladaindong and analyzed using a Single Particle Soot Photometer (SP2) provides the first long-term (1843–1982) record of BC from the central Tibetan Plateau. Post 1940 the record is characterized by an increased occurrence of years with above average BC, and the highest BC values of the record. The BC increase in recent decades is likely caused by a combination of increased emissions from regional BC sources, and a reduction in snow accumulation. Guoqu glacier has received no net ice accumulation since the 1980s, and is a potential example of a glacier where an increase in the equilibrium line altitude is exposing buried high impurity layers. That BC concentrations in the uppermost layers of the Geladaindong ice core are not substantially higher relative to deeper in the ice core suggests that some of the BC that must have been deposited on Guoqu glacier via wet or dry deposition between 1983 and 2005 has been removed from the surface of the glacier, potentially via supraglacial or englacial meltwater.

Greenland's ice sheet mass loss rate has tripled since the mid-1950s in concert with sharply lowered albedo leading to increased absorption of solar radiation and enhanced surface melt. Snow and ice melt driven by solar absorption is enhanced by the presence of light absorbing particles (LAPs), such as black carbon (BC) and dust. Yet, the LAP impact on melt is poorly constrained, partly due to scarce availability of in-situ measurements. Here, we present a survey of snow properties and LAPs deposited in winter snow layers at five sites in southwest Greenland collected in May 2017. At these sites, BC and dust concentrations were 0.62 ± 0.35 ng g-1 and 2.09 ± 1.60 µg g-1, respectively. By applying the SNICAR model, we show the LAP influence on albedo through the combined effect of surface darkening and snow metamorphism. While the LAP concentrations are low, they result in a 1.7% and 3.0% reduction in albedo within the visible spectrum for spring and summer, respectively. Past studies have shown that even minor LAP induced albedo reductions, if widespread, can have a large impact on the overall surface mass balance. SNICAR simulations constrained by our measurements show that LAP-snow aging feedback reduce albedo reduction 4 to 10 times more than previously thought, therefore LAPs are likely a significant contributor to Greenland's accelerated mass loss. As far as we know, this is the first field study to consider the LAP impact on snow aging on the Greenland ice sheet. [ABSTRACT FROM AUTHOR]

The Tibetan Plateau (TP) and its surroundings, known as the Third Pole, play an important role in the regional and global climate and hydrological cycle. Carbonaceous aerosols (CAs), including black carbon (BC) and organic carbon (OC), can directly/indirectly absorb and scatter solar radiation, and change the energy balance on Earth. CAs, along with other atmospheric pollutants (e.g., mercury), can frequently be transported over long distances into the inland TP. During the last decade, a coordinated monitoring network and research program on Atmospheric Pollution and Cryospheric Change (APCC) has been gradually setup and continuously operated within the Third Pole regions to investigate the linkage between atmospheric pollutants and cryospheric change. This paper presents a systematic dataset of BC, OC, water soluble organic carbon (WSOC), and water insoluble organic carbon (WIOC) from aerosols (19 stations), glaciers (17 glaciers, including samples from surface snow/ice, snowpit, and two ice cores), snow cover (2 stations continuous observed, and 138 sites surveyed), precipitation (6 stations), and lake sediment cores (7 lakes) collected across the TP and its surroundings, as the first dataset released from this APCC program. These data were created based on online (in-situ) and laboratory measurements. High-resolution (daily scale) atmospheric equivalent BC (eBC) concentrations were obtained by using an aethalometer (AE-33) in the Mt. Everest (Qomolangma) region, which can provide a new insight into the mechanism of BC transportation over the Himalayas. Spatial distributions of BC, OC, WSOC and WIOC from aerosols, glaciers, snow cover, and precipitation indicated different features among the different regions of the TP, which were mostly influenced by emission sources, transport, and deposition processes. Several hundred years of refractory BC (rBC) records from ice cores and BC from lake sediment cores revealed the strength of human activities since the industrial revolution. BC isotopes from glaciers and aerosols identified the relative contributions of biomass and fossil fuel combustion to BC deposition on the Himalayas and TP. Mass absorption cross section of BC and WSOC from aerosol, glaciers, snow cover, and precipitation samples were also provided. This updated dataset is released to the scientific communities focusing on atmospheric science, cryospheric science, hydrology, climatology and environmental science. The related datasets are presented in the form of excel files. These files are available to download from the State Key Laboratory of Cryosphere Sciences, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences at Lanzhou https://doi.org/10.12072/ncdc.NIEER.db0114.2021, Kang and Zhang, 2021). In the future, datasets of mercury, heavy metals, and POPs will be reported. [ABSTRACT FROM AUTHOR]

Himalayan glaciers are melting due to atmospheric warming with the potential to limit access to water for more than 25% of the global population that reside in these glacier meltwater catchments. Black carbon has been implicated as a factor that is contributing to Himalayan glacier melt, but its sources and mechanisms of delivery to the Himalayas remain controversial. Here, we provide a 211-year ice core record spanning 1781 – 1992 CE for refractory black carbon (rBC) deposition from the Dasuopu glacier ice core, that has to date provided the highest elevation ice core record (7200 m). We report an average rBC concentration of 1.5 µg/L (SD = 5.0, n = 1628) over the 211-year period. An increase in the frequency and magnitude of rBC deposition occurs after 1877 CE, accompanied by decreased snow accumulation associated with a shift in the North Atlantic Oscillation Index to a positive phase. Typically, rBC is deposited onto Dasuopu glacier during the non-monsoon season, and short-lived increases in rBC concentration are associated with periods of drought within neighboring regions in north-west India, Afghanistan and Pakistan. Using a combination of spectral and back trajectory analyses, and comparison with a concurrent analysis of trace metals at equivalent depths in the same ice core, we show that biomass burning resulting from dry conditions is a source of rBC to the central Himalaya, and is responsible for deposition that is up to 60 times higher than the average rBC concentration over the time period analyzed. We suggest that biomass burning is a significant source of rBC to the central Himalaya, and that the rBC record can be used to identify periods of drought in nearby regions that are up-wind of Dasuopu glacier. [ABSTRACT FROM AUTHOR]