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1. Contribution of biomass burning to black carbon deposition on Andean glaciers: consequences for radiative forcing

   https://doi.org/10.1088/1748-9326/acb371  

   Bonilla, E. X.; Mickley, L. J.; Beaudon, E. G.; Thompson, L. G.; Rodriguez, W. E.; Encarnación, R. Cruz; Whicker, C. A.; Flanner, M. G.; Schmitt, C. G.; Ginot, P. (February 2023, Environmental Research Letters)

   Abstract Andean glaciers have melted rapidly since the 1960s. While some melting is likely due to anthropogenic climate change driven by increasing greenhouse gases, deposition of light-absorbing particles such as black carbon (BC) may also play a role. We hypothesize that BC from fires in the Amazon Basin and elsewhere may be deposited on Andean glaciers, reducing the surface albedo and inducing further melting. Here we investigate the role of BC deposition on albedo changes in the Andes for 2014–2019 by combining atmospheric chemistry modeling with observations of BC in snow or ice at four mountain sites in Peru (Quelccaya, Huascarán, Yanapaccha, and Shallap) and at one site in Bolivia (Illimani). We find that annual mean ice BC concentrations simulated by the chemical transport model GEOS-Chem for 2014–2019 are roughly consistent with those observed at the site with the longest record, Huascarán, with overestimates of 15%–40%. Smoke from fires account for 20%–70% of total wet and dry deposition fluxes, depending on the site. The rest of BC deposited comes from fossil fuel combustion. Using a snow albedo model, we find that the annual mean radiative forcing from the deposition of smoke BC alone on snow ranges from +0.1 to +3.2 W m⁻²under clear-sky conditions, with corresponding average albedo reductions of 0.04%–1.1%. These ranges are dependent on site and snow grain size. This result implies a potentially significant climate impact of biomass burning in the Amazon on radiative forcing in the Andes. 

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2. Antarctica as a ‘natural laboratory’ for the critical assessment of the archaeological validity of early stone tool sites

   https://doi.org/10.15184/aqy.2023.4  

   Eren, Metin I.; Bebber, Michelle R.; Buchanan, Briggs; Grunow, Anne; Key, Alastair; Lycett, Stephen J.; Maletic, Erica; Riley, Teal R. (January 2023, Antiquity)

   Lithic technologies dominate understanding of early humans, yet natural processes can fracture rock in ways that resemble artefacts made by Homo sapiens and other primates. Differentiating between fractures made by natural processes and primates is important for assessing the validity of early and controversial archaeological sites. Rather than depend on expert authority or intuition, the authors propose a null model of conchoidally fractured Antarctic rocks. As no primates have ever occupied the continent, Antarctica offers a laboratory for generating samples that could only have been naturally fractured. Examples that resemble artefacts produced by primates illustrate the potential of ‘archaeological’ research in Antarctica for the evaluation of hominin sites worldwide. 

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3. Habitat suitability of biocrust communities in a cold desert ecosystem

   https://doi.org/10.1002/ece3.11649  

   Power, Sarah_N; Thomas, Valerie_A; Salvatore, Mark_R; Barrett, John_E (June 2024, Ecology and Evolution)

   Abstract Drylands are unique among terrestrial ecosystems in that they have a significant proportion of primary production facilitated by non‐vascular plants such as colonial cyanobacteria, moss, and lichens, i.e., biocrusts, which occur on and in the surface soil. Biocrusts inhabit all continents, including Antarctica, an increasingly dynamic continent on the precipice of change. Here, we describe in‐situ field surveying and sampling, remote sensing, and modeling approaches to assess the habitat suitability of biocrusts in the Lake Fryxell basin of Taylor Valley, Antarctica, which is the main site of the McMurdo Dry Valleys Long‐Term Ecological Research Program. Soils suitable for the development of biocrusts are typically wetter, less alkaline, and less saline compared to unvegetated soils. Using random forest models, we show that gravimetric water content, electrical conductivity, and snow frequency are the top predictors of biocrust presence and biomass. Areas most suitable for the growth of dense biocrusts are soils associated with seasonal snow patches. Using geospatial data to extrapolate our habitat suitability model to the whole basin predicts that biocrusts are present in 2.7 × 10⁵m²and contain 11–72 Mg of aboveground carbon, based on the 90% probability of occurrence. Our study illustrates the synergistic effect of combining field and remote sensing data for understanding the distribution and biomass of biocrusts, a foundational community in the carbon balance of this region. Extreme weather events and changing climate conditions in this region, especially those influencing snow accumulation and persistence, could have significant effects on the future distribution and abundance of biocrusts and therefore soil organic carbon storage in the McMurdo Dry Valleys. 

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4. Geology of West Antarctica

   Siddoway, Christine Smith (January 2021, Beiträge zur regionalen Geologie der Erde)

   Kleinschmidt, Georg (Ed.)

   The work is Chapter Three in a volume that provides a comprehensive overview of the geology of the Antarctic continent. The book represents the first comprehensive update of Antarctic geology in 25 years or more. Knowledge of the geology of Antarctica -- even if based on the meager <2% of rock exposure for this continent-- has immeasurably increased over that quarter-century. Individual chapters cover the regional geology of the seven main physiographic regions of Antarctica: -the Antarctic Peninsula, -West Antarctica (Marie Byrd Land and Enderby Land), -Transantarctic Mountains, -the Shackleton Range and its surroundings (including the Bertrab, Littlewood and Moltke Nunataks), -Dronning Maud Land, -Lambert Glacier and the area surrounding it, -East Antarctica from Kaiser-Wilhelm-II.-Land to George V Land/Terre Adélie. Each chapter contains a topographic, historical and geological overview, a description of the respective geological units, their stratigraphy and related data and the tectonic structure of the respective region. The seven chapters were written by acknowledged specialists in their field who place the regional geology into a continent-wide/plate tectonic/geological context. 

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5. Antarctic Firn Characterization via Wideband Microwave Radiometry

   https://doi.org/10.3390/rs14092258  

   Kar, Rahul; Aksoy, Mustafa; Kaurejo, Dua; Atrey, Pranjal; Devadason, Jerusha Ashlin (May 2022, Remote Sensing)

   Recent studies have demonstrated that wideband microwave radiometers provide significant potential for profiling important subsurface polar firn characteristics necessary to understand the dynamics of the cryosphere and predict future changes in ice and snow coverage. Different frequencies within the wide spectra of radiometers result in different electromagnetic propagation losses and thus reveal characteristics at different depths in ice and snow. This paper, expanding on those investigations, explores the utilization of the Global Precipitation Measurement (GPM) constellation as a single wideband (6.93 GHz–91.655 GHz) spaceborne radiometer, covering the entire microwave spectrum from C-band to W-band, to profile subsurface properties of the Antarctic firn. Results of the initial analyses over Concordia and Vostok Stations in Antarctica indicate that GPM brightness temperature measurements provide critical information regarding the subsurface temperatures and physical properties of the firn from the surface down to several meters of depth. Considering the high spatiotemporal coverage of polar-orbiting spaceborne radiometers, these results are promising for future continent-level thermal and physical characterization of the Antarctic firn. 

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