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1. Fingerprinting the recovery of Antarctic ozone

   https://doi.org/10.1038/s41586-025-08640-9  

   Wang, Peidong; Solomon, Susan; Santer, Benjamin D; Kinnison, Douglas E; Fu, Qiang; Stone, Kane A; Zhang, Jun; Manney, Gloria L; Millan, Luis F (March 2025, Nature)

   The Antarctic ozone “hole” was discovered in 1985, and man-made ozone- depleting substances (ODS) are its primary cause. Following reductions of ODSs under the Montreal Protocol, signs of ozone recovery have been reported, based largely on observations and broad yet compelling model-data comparisons. While such approaches are highly valuable, they don't provide rigorous statistical detection of the temporal and spatial structure of Antarctic ozone recovery in the presence of internal climate variability. Here, we apply pattern-based detection and attribution methods as employed in climate change studies to separate anthropogenically forced ozone responses from internal variability, relying on trend pattern information as a function of month and height. The analysis uses satellite observations together with single-model and multi-model ensemble simulations to identify and quantify the month-height Antarctic ozone recovery “fingerprint”. We demonstrate that the data and simulations show remarkable agreement in the fingerprint pattern of the ozone response to decreasing ODSs since 2005. We also show that ODS forcing has enhanced ozone internal variability during the austral spring, influencing detection of forced responses and their time of emergence. Our results provide robust statistical and physical evidence that actions taken under the Montreal Protocol to reduce ODSs are indeed resulting in the beginning of Antarctic ozone recovery, defined as increases in ozone consistent with expected month-height patterns. 

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2. The Antarctic Silicon Trap

   https://doi.org/10.3389/frym.2023.1180915  

   Closset, Ivia; Cassarino, Lucie (December 2023, Frontiers for Young Minds)

   The Southern Ocean, the ocean encircling Antarctica, has been described by explorers as cold, empty, and dangerous. Despite this, it is a paradise for tiny algae called diatoms that are crucial players in the regulation of our climate. Why are these tiny organisms so happy in this cold and far away ocean? Diatoms have a solid shell made of a glass-like material called silica, so they need to find silicon in surface waters to build it. The Southern Ocean is the perfect place for diatoms because it is full of silicon compared to the other oceans. This is due to a special phenomenon called the silicon pump, which makes the Southern Ocean a giant trap for silicon. In this article, we point out the central role of the Southern Ocean in the regulation of Earth’s climate and how it controls the distribution of silicon and the wellbeing of diatoms in Antarctic waters. 

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3. The energetic cost of early reproductive development in juvenile Antarctic krill at the Western Antarctic Peninsula

   https://doi.org/10.3389/fmars.2022.1009385  

   Steinke, Kirsten B.; Bernard, Kim S.; Fontana, Julia M.; Copeman, Louise A.; Garcia, Lani M. (December 2022, Frontiers in Marine Science)

   The overwinter survival mechanisms of Antarctic krill, Euphausia superba , are poorly characterized, especially for juveniles. It has been suggested that juveniles adopt a mix of strategies characteristic of both larvae and adults. Like larvae, they may feed opportunistically throughout winter when food is available, and like adults they may be able to suppress their metabolism when food is scarce. In this study we look at the overwinter strategies of juvenile krill and how their reproductive development changes when energy input exceeds what is necessary for survival. We take a closer look at how the sexual maturation of juvenile krill progresses in response to different environmental conditions throughout the fall and winter. We exposed juvenile Antarctic krill to four different “food environment scenarios”, supplementing them with various diets from May to September 2019 that were representative of environmental conditions that they may encounter in different regions of the Western Antarctic Peninsula during autumn and winter. Each month, we measured the physiology and condition of the krill, and assessed the reproductive development of females. We found that when female juvenile krill have greater energy reserves than what is needed to survive the winter, they will begin to sexually mature. Further, when there are sufficient levels of the fatty acids eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and 16:4 ( n-1 ), krill are likely to be in a more reproductive advanced stage. However, when lipids, EPA, DHA and 16:4 ( n-1 ) are depleted throughout the winter, juvenile female krill lose their ability to develop reproductively. We also found that sexual development is an energy intensive process that requires high respiration rates in juvenile krill. Furthermore, when juvenile females expend energy maturing, their physiological condition declines. This trade-off between early reproductive development and condition in juvenile female krill has important implications for individual health and population fecundity. Gaining a better understanding of the mechanisms behind juvenile krill winter survival strategies and their consequences will allow us to predict how future change at the western Antarctic Peninsula may affect krill population dynamics, especially in light of a warming climate. 

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4. Chronology of the Palmer Deep site, Antarctic Peninsula: a Holocene palaeoenvironmental reference for the circum-Antarctic

   https://doi.org/10.1191/095968301673881493  

   Domack, E; Leventer, A; Dunbar, R; Taylor, F; Brachfeld, S; Sjunneskog, C (January 2001, The Holocene)

   Palmer Deep sediment cores are used to produce the first high-resolution, continuous late Pleistocene to Holocene time-series from the Antarctic marine system. The sedimentary record is dated using accelerator mass spectrometer radiocarbon methods on acid insoluble organic matter and foraminiferal calcite. Fifty-four radiocarbon analyses are utilized in the dating which provides a calibrated timescale back to 13 ka BP. Reliability of resultant ages on organic matter is assured because duplicates produce a standard deviation from the surface age of less than laboratory error (i.e., ±50 years). In addition, surface organic matter ages at the site are in excellent agreement with living calcite ages at the accepted reservoir age of 1260 years for the Antarctic Peninsula. Spectral analyses of the magnetic susceptibility record against the age model reveal unusually strong periodicity in the 400,–200 and 50-70 year frequency bands, similar to other high-resolution records from the Holocene but, so far, unique for the circum-Antarctic. Here we show that comparison to icecore records of specific climatic events (e.g., the ’Little Ice Age‘, Neoglacial, Hypsithermal, and the Bølling/Allerød to Younger Dryas transition) provides improved focus upon the relative timing of atmosphere/ocean changes between the northern anid southern high latitudes. 

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5. Factors impacting the timing of reproductive development in female Antarctic krill at the northwestern Antarctic Peninsula

   https://doi.org/10.3389/fmars.2024.1383175  

   Steinke, Kirsten B; Bernard, Kim S; Reiss, Christian S; Walsh, Jennifer; Correa, Giancarlo M; Stammerjohn, Sharon E (July 2024, Frontiers in Marine Science)

   The northwestern Antarctic Peninsula is an important spawning, recruitment, and overwintering ground for Antarctic krill. The region is warming rapidly, and the current impacts of climate and environmental variability on the reproductive cycle of krill remain unclear. Here, we examine the reproductive stage of female krill in the austral winter from 2012 to 2016 in relation to climate and environmental data to assess what factors influence the timing of reproductive development. We observed significant interannual variability in the degree of maturation in female krill, ranging from 48% of female krill measured at a station in 2016 to a maximum of 94% of female krill measured at a station in 2014. On average, across all five years, three-quarters of the female krill sampled were in the stage known as previtellogenesis, the point at which the onset of sexual maturity begins. The preceding spring, summer, and autumn Southern Annular Mode and the Multivariate El Niño Index explained most of the variance in the data and indicated a strong, preconditioning storm-related effect on environmental conditions leading up to winter, affecting krill maturation status at the end of the winter season. Results from our study can be used to improve krill population models that are necessary for the management of the krill fishery and for conservation at the northwestern Antarctic Peninsula. 

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