Artykuły w czasopismach na temat „Antarctic Ocean”
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1
Sirenko, B. I. "First finding of a widely distributed Antarctic chiton species (Mollusca: Polyplacophora) in the North Pacific". Ruthenica, Russian Malacological Journal 29, nr 1 (14.01.2019): 71–74. http://dx.doi.org/10.35885/ruthenica.2019.29(1).3.
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For the first time, the widely spread Antarctic species Leptochiton antarcticus was found at the Emperor Seamounts in the North Pacific Ocean. In spite of a large distance between the Emperor Seamounts and Antarctica, the found specimen have very similar shell, girdle, radula and gill features to the type material. I propose that L. antarcticus spread to the North Pacific from the Antarctic via a deep-water current near the ocean floor, and perhaps it inhabits the slopes of islands and continents from the South Ocean to the Emperor Seamounts.
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Jacka, Tim H., William F. Budd i Andrew Holder. "A further assessment of surface temperature changes at stations in the Antarctic and Southern Ocean, 1949–2002". Annals of Glaciology 39 (2004): 331–38. http://dx.doi.org/10.3189/172756404781813907.
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AbstractStatistical analyses are carried out, of the annual mean surface air temperature at occupied stations and automatic weather stations in the Antarctic and Southern and Pacific Oceans. The data are studied in four groupings: coastal Antarctica (excluding the Antarctic Peninsula), inland Antarctica, the Antarctic Peninsula and the Southern Ocean/Pacific Ocean islands. We find that within each of these four groupings the average trend indicates warming. For coastal Antarctica the trend is ∼0.8°C(100 a)–1. Inland, the results are less clear, but the mean trend is to a warming of ∼1.0°C(100 a)–1. For the Peninsula stations it is ∼4.4°C(100 a)–1, and for the ocean stations the average trend is ∼0.8°C(100 a)–1. The results indicate a reduction in the warming trend since our last analysis 6 years ago. While the Pinatubo (Philippines) volcanic eruption may have had some influence on this reduction in the warming rate, examination of the interannual variations in the temperature record shows variability has continued high since the recovery from any such effect. There has been a further period of cooler temperatures in coastal and inland Antarctica in that time, yet a warmer period in the Peninsula and ocean islands.
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Jun, Sang-Yoon, Joo-Hong Kim, Jung Choi, Seong-Joong Kim, Baek-Min Kim i Soon-Il An. "The internal origin of the west-east asymmetry of Antarctic climate change". Science Advances 6, nr 24 (czerwiec 2020): eaaz1490. http://dx.doi.org/10.1126/sciadv.aaz1490.
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Recent Antarctic surface climate change has been characterized by greater warming trends in West Antarctica than in East Antarctica. Although this asymmetric feature is well recognized, its origin remains poorly understood. Here, by analyzing observation data and multimodel results, we show that a west-east asymmetric internal mode amplified in austral winter originates from the harmony of the atmosphere-ocean coupled feedback off West Antarctica and the Antarctic terrain. The warmer ocean temperature over the West Antarctic sector has positive feedback, with an anomalous upper-tropospheric anticyclonic circulation response centered over West Antarctica, in which the strength of the feedback is controlled by the Antarctic topographic layout and the annual cycle. The current west-east asymmetry of Antarctic surface climate change is undoubtedly of natural origin because no external factors (e.g., orbital or anthropogenic factors) contribute to the asymmetric mode.
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Wang, Hailong, Jeremy G. Fyke, Jan T. M. Lenaerts, Jesse M. Nusbaumer, Hansi Singh, David Noone, Philip J. Rasch i Rudong Zhang. "Influence of sea-ice anomalies on Antarctic precipitation using source attribution in the Community Earth System Model". Cryosphere 14, nr 2 (4.02.2020): 429–44. http://dx.doi.org/10.5194/tc-14-429-2020.
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Abstract. We conduct sensitivity experiments using a general circulation model that has an explicit water source tagging capability forced by prescribed composites of pre-industrial sea-ice concentrations (SICs) and corresponding sea surface temperatures (SSTs) to understand the impact of sea-ice anomalies on regional evaporation, moisture transport and source–receptor relationships for Antarctic precipitation in the absence of anthropogenic forcing. Surface sensible heat fluxes, evaporation and column-integrated water vapor are larger over Southern Ocean (SO) areas with lower SICs. Changes in Antarctic precipitation and its source attribution with SICs have a strong spatial variability. Among the tagged source regions, the Southern Ocean (south of 50∘ S) contributes the most (40 %) to the Antarctic total precipitation, followed by more northerly ocean basins, most notably the South Pacific Ocean (27%), southern Indian Ocean (16 %) and South Atlantic Ocean (11 %). Comparing two experiments prescribed with high and low pre-industrial SICs, respectively, the annual mean Antarctic precipitation is about 150 Gt yr−1 (or 6 %) more in the lower SIC case than in the higher SIC case. This difference is larger than the model-simulated interannual variability in Antarctic precipitation (99 Gt yr−1). The contrast in contribution from the Southern Ocean, 102 Gt yr−1, is even more significant compared to the interannual variability of 35 Gt yr−1 in Antarctic precipitation that originates from the Southern Ocean. The horizontal transport pathways from individual vapor source regions to Antarctica are largely determined by large-scale atmospheric circulation patterns. Vapor from lower-latitude source regions takes elevated pathways to Antarctica. In contrast, vapor from the Southern Ocean moves southward within the lower troposphere to the Antarctic continent along moist isentropes that are largely shaped by local ambient conditions and coastal topography. This study also highlights the importance of atmospheric dynamics in affecting the thermodynamic impact of sea-ice anomalies associated with natural variability on Antarctic precipitation. Our analyses of the seasonal contrast in changes of basin-scale evaporation, moisture flux and precipitation suggest that the impact of SIC anomalies on regional Antarctic precipitation depends on dynamic changes that arise from SIC–SST perturbations along with internal variability. The latter appears to have a more significant effect on the moisture transport in austral winter than in summer.
5
Lu, C. C., i R. Williams. "Contribution to the biology of squid in the Prydz Bay region, Antarctica". Antarctic Science 6, nr 2 (czerwiec 1994): 223–29. http://dx.doi.org/10.1017/s0954102094000349.
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The teuthoid fauna of the Prydz Bay region of the Southern Ocean (Indian Ocean sector) has been studied based on the material collected from 1981–1991 using a rectangular midwater trawl (RMT-8), pelagic trawl (IYGPT), and bottom trawl. Eight species of squid have been recognized: Brachioteuthis sp., Kondakovia longimana, Bathyteuthis abyssicola, Psychroteuthis glacialis, Alluroteuthis antarcticus, Mastigoteuthis psychrophila, Mesonychoteuthis hamiltoni and Galiteuthis glacialis. Size frequency distribution, geographical and vertical distributions of each species as well as diets of common species are analysed. There is no evidence of a diel vertical migration but ontogenetic descent appears to occur in P. glacialis and G. glacialis. Antarctic krill, Euphausia superba and the Antarctic silverfish, Pleuragramma antarcticum are important prey for most species with cannibalism occurring in P. glacialis, A. antarcticus and M. hamiltoni. Equations for calculating total weight from mantle length, and mantle length and total weight from upper and lower rostral length are provided for B. abyssicola, P. glacialis, A. antarcticus, M. psychrophila, and G. glacialis.
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Cunningham, Stuart A. "Southern Ocean circulation". Archives of Natural History 32, nr 2 (październik 2005): 265–80. http://dx.doi.org/10.3366/anh.2005.32.2.265.
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The Discovery Investigations of the 1930s provided a compelling description of the main elements of the Southern Ocean circulation. Over the intervening years, this has been extended to include ideas on ocean dynamics based on physical principles. In the modern description, the Southern Ocean has two main circulations that are intimately linked: a zonal (west-east) circumpolar circulation and a meridional (north-south) overturning circulation. The Antarctic Circumpolar Current transports around 140 million cubic metres per second west to east around Antarctica. This zonal circulation connects the Atlantic, Indian and Pacific Oceans, transferring and blending water masses and properties from one ocean basin to another. For the meridional circulation, a key feature is the ascent of waters from depths of around 2,000 metres north of the Antarctic Circumpolar Current to the surface south of the Current. In so doing, this circulation connects deep ocean layers directly to the atmosphere. The circumpolar zonal currents are not stable: meanders grow and separate, creating eddies and these eddies are critical to the dynamics of the Southern Ocean, linking the zonal circumpolar and meridional circulations. As a result of this connection, a global three-dimensional ocean circulation exists in which the Southern Ocean plays a central role in regulating the Earth's climate.
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England, Matthew H., David K. Hutchinson, Agus Santoso i Willem P. Sijp. "Ice–Atmosphere Feedbacks Dominate the Response of the Climate System to Drake Passage Closure". Journal of Climate 30, nr 15 (sierpień 2017): 5775–90. http://dx.doi.org/10.1175/jcli-d-15-0554.1.
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The response of the global climate system to Drake Passage (DP) closure is examined using a fully coupled ocean–atmosphere–ice model. Unlike most previous studies, a full three-dimensional atmospheric general circulation model is included with a complete hydrological cycle and a freely evolving wind field, as well as a coupled dynamic–thermodynamic sea ice module. Upon DP closure the initial response is found to be consistent with previous ocean-only and intermediate-complexity climate model studies, with an expansion and invigoration of the Antarctic meridional overturning, along with a slowdown in North Atlantic Deep Water (NADW) production. This results in a dominance of Southern Ocean poleward geostrophic flow and Antarctic sinking when DP is closed. However, within just a decade of DP closure, the increased southward heat transport has melted back a substantial fraction of Antarctic sea ice. At the same time the polar oceans warm by 4°–6°C on the zonal mean, and the maximum strength of the Southern Hemisphere westerlies weakens by ≃10%. These effects, not captured in models without ice and atmosphere feedbacks, combine to force Antarctic Bottom Water (AABW) to warm and freshen, to the point that this water mass becomes less dense than NADW. This leads to a marked contraction of the Antarctic overturning, allowing NADW to ventilate the abyssal ocean once more. Poleward heat transport settles back to very similar values as seen in the unperturbed DP open case. Yet remarkably, the equilibrium climate in the closed DP configuration retains a strong Southern Hemisphere warming, similar to past studies with no dynamic atmosphere. However, here it is ocean–atmosphere–ice feedbacks, primarily the ice-albedo feedback and partly the weakened midlatitude jet, not a vigorous southern sinking, which maintain the warm polar oceans. This demonstrates that DP closure can drive a hemisphere-scale warming with polar amplification, without the presence of any vigorous Southern Hemisphere overturning circulation. Indeed, DP closure leads to warming that is sufficient over the West Antarctic Ice Sheet region to inhibit ice-sheet growth. This highlights the importance of the DP gap, Antarctic sea ice, and the associated ice-albedo feedback in maintaining the present-day glacial state over Antarctica.
8
Bell, Robin E., i Helene Seroussi. "History, mass loss, structure, and dynamic behavior of the Antarctic Ice Sheet". Science 367, nr 6484 (19.03.2020): 1321–25. http://dx.doi.org/10.1126/science.aaz5489.
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Antarctica contains most of Earth’s fresh water stored in two large ice sheets. The more stable East Antarctic Ice Sheet is larger and older, rests on higher topography, and hides entire mountain ranges and ancient lakes. The less stable West Antarctic Ice Sheet is smaller and younger and was formed on what was once a shallow sea. Recent observations made with several independent satellite measurements demonstrate that several regions of Antarctica are losing mass, flowing faster, and retreating where ice is exposed to warm ocean waters. The Antarctic contribution to sea level rise has reached ~8 millimeters since 1992. In the future, if warming ocean waters and increased surface meltwater trigger faster ice flow, sea level rise will accelerate.
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TAVARES, MARCOS, i GUSTAVO A. S. DE MELO. "Discovery of the first known benthic invasive species in the Southern Ocean: the North Atlantic spider crab Hyas araneus found in the Antarctic Peninsula". Antarctic Science 16, nr 2 (czerwiec 2004): 129–31. http://dx.doi.org/10.1017/s0954102004001877.
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The Southern Ocean around Antarctica is no longer free from invasive marine species. The North Atlantic spider crab Hyas araneus (Linnaeus, 1758) (Crustacea: Decapoda: Majidae) has been recorded for the first time from the Antarctic Peninsula. Isolated for at least 25 million years, the endemic Antarctic Southern Ocean marine fauna is now being exposed to human-mediated influx of exotic species. Invasive species and polar warming combined can foster the probability of arrival and colonization by non-indigenous species, with unpredictable consequences for the Antarctic marine biota.
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Chown, Steven L., i Cassandra M. Brooks. "The State and Future of Antarctic Environments in a Global Context". Annual Review of Environment and Resources 44, nr 1 (17.10.2019): 1–30. http://dx.doi.org/10.1146/annurev-environ-101718-033236.
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Antarctica and the Southern Ocean comprise a critical part of the Earth System. Their environments are better understood than ever before, yet the region remains poorly considered among international agreements to improve the state of the global environment. In part the situation owes to isolated regional regulation within the Antarctic Treaty System, and in part to the dated notion that Antarctica and the Southern Ocean are well conserved and relatively free from human impact. Here we review growth in knowledge of Antarctic environments and anthropogenic pressures on them. We show that the region's unusual diversity is facing substantial local and globally mediated anthropogenic pressure, on a par with environments globally. Antarctic environmental management and regulation is being challenged to keep pace with the change. Much benefit can be derived from consideration of Antarctic environmental and resource management in the context of global agreements.
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Kennicutt, M. C., Y. D. Kim, M. Rogan-Finnemore, S. Anandakrishnan, S. L. Chown, S. Colwell, D. Cowan i in. "Delivering 21st century Antarctic and Southern Ocean science". Antarctic Science 28, nr 6 (21.10.2016): 407–23. http://dx.doi.org/10.1017/s0954102016000481.
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AbstractThe Antarctic Roadmap Challenges (ARC) project identified critical requirements to deliver high priority Antarctic research in the 21st century. The ARC project addressed the challenges of enabling technologies, facilitating access, providing logistics and infrastructure, and capitalizing on international co-operation. Technological requirements include: i) innovative automated in situ observing systems, sensors and interoperable platforms (including power demands), ii) realistic and holistic numerical models, iii) enhanced remote sensing and sensors, iv) expanded sample collection and retrieval technologies, and v) greater cyber-infrastructure to process ‘big data’ collection, transmission and analyses while promoting data accessibility. These technologies must be widely available, performance and reliability must be improved and technologies used elsewhere must be applied to the Antarctic. Considerable Antarctic research is field-based, making access to vital geographical targets essential. Future research will require continent- and ocean-wide environmentally responsible access to coastal and interior Antarctica and the Southern Ocean. Year-round access is indispensable. The cost of future Antarctic science is great but there are opportunities for all to participate commensurate with national resources, expertise and interests. The scope of future Antarctic research will necessitate enhanced and inventive interdisciplinary and international collaborations. The full promise of Antarctic science will only be realized if nations act together.
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E. Davis. Jr., William. "Heard Island: Southern Ocean Sentinel". Pacific Conservation Biology 13, nr 2 (2007): 145. http://dx.doi.org/10.1071/pc070145.
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Heard Island is one of the most remote places on earth. It is of volcanic origin (and currently volcanically active) on the submarine Kerguelen Plateau in the Southern Ocean, roughly 4 000 km south-west of Australia, 1 500 km from Antarctica, 3 750 km from Africa, and 7 500 km from India. The island is 367 km2 in area at latitude 53�S, south of the Antarctic Polar Front (Antarctic Convergence), is 70% covered with glaciers, and has a geologic, biologic and human history of substantial interest. Because of its remoteness, relative recent discovery (1853), and infrequent human visitation, it is pristine with no human-introduced plants or mammals.
13
MACKENSEN, ANDREAS. "Changing Southern Ocean palaeocirculation and effects on global climate". Antarctic Science 16, nr 4 (30.11.2004): 369–86. http://dx.doi.org/10.1017/s0954102004002202.
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Southern Ocean palaeocirculation is clearly related to the formation of a continental ice sheet on Antarctica and the opening of gateways between Antarctica and the Australian and South American continents. Palaeoenvironmental proxy records from Southern Ocean sediment cores suggest ice growth on Antarctica beginning by at least 40 million years (Ma) ago, and the opening of Tasmania–Antarctic and Drake Passages to deep-water flow around 34 and 31 ± 2 Ma, respectively. So, the Eocene/Oligocene transition appears to mark the initiation of the Antarctic Circumpolar Current and thus the onset of thermal isolation of Antarctica with a first major ice volume growth on East Antarctic. There is no evidence for a significant cooling of the deep ocean associated with this rapid (< 350 000 years) continental ice build-up. After a long phase with frequent ice sheets growing and decaying, in the middle Miocene at about 14 Ma, a re-establishment of an ice sheet on East Antarctica and the Pacific margin of West Antarctica was associated with an increased southern bottom water formation, and a slight cooling of the deep ocean, but with no permanent drop in atmospheric pCO2. During the late Pleistocene on orbital time scales a temporal correlation between changes in atmospheric pCO2 and proxy records of deep ocean temperatures, continental ice volume, sea ice extension, and deep-water nutrient contents is documented. I discuss hypotheses that call for a dominant control of glacial to interglacial atmospheric pCO2 variations by Southern Ocean circulation dynamics. Millennial to centennial climate variability is a global feature, but there is contrasting evidence from various palaeoclimate archives that indicate both interhemispheric synchrony and asynchrony. The role of the Southern Ocean, however, in triggering or modulating climate variability on these time scales only recently received some attention and is not yet adequately investigated.
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Bougamont, Marion, Elizabeth Hunke i Slawek Tulaczyk. "Sensitivity of ocean circulation and sea-ice conditions to loss of West Antarctic ice shelves and ice sheet". Journal of Glaciology 53, nr 182 (2007): 490–98. http://dx.doi.org/10.3189/002214307783258440.
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AbstractWe use a global coupled ocean-sea ice model to test the hypothesis that the disintegration of the West Antarctic ice sheet (WAIS), or just its ice shelves, may modify ocean circulation and sea-ice conditions in the Southern Ocean. We compare the results of three model runs: (1) a control run with a standard (modern) configuration of landmask in West Antarctica, (2) a no-shelves run with West Antarctic ice shelves removed and (3) a no-WAIS run. In the latter two runs, up to a few million square kilometres of new sea surface area opens to sea-ice formation, causing the volume and extent of Antarctic sea-ice cover to increase compared with the control run. In general, near-surface waters are cooler around Antarctica in the no-shelves and no-WAIS model runs than in the control run, while warm intermediate and deep waters penetrate further south, increasing poleward heat transport. Varying regional responses to the imposed changes in landmask configuration are determined by the fact that Antarctic polynyas and fast ice develop in different parts of the model domain in each run. Model results suggest that changes in the extent of WAIS may modify oceanographic conditions in the Southern Ocean.
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Singh, Hansi K. A., Cecilia M. Bitz i Dargan M. W. Frierson. "The Global Climate Response to Lowering Surface Orography of Antarctica and the Importance of Atmosphere–Ocean Coupling". Journal of Climate 29, nr 11 (20.05.2016): 4137–53. http://dx.doi.org/10.1175/jcli-d-15-0442.1.
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Abstract A global climate model is used to study the effect of flattening the orography of the Antarctic Ice Sheet on climate. A general result is that the Antarctic continent and the atmosphere aloft warm, while there is modest cooling globally. The large local warming over Antarctica leads to increased outgoing longwave radiation, which drives anomalous southward energy transport toward the continent and cooling elsewhere. Atmosphere and ocean both anomalously transport energy southward in the Southern Hemisphere. Near Antarctica, poleward energy and momentum transport by baroclinic eddies strengthens. Anomalous southward cross-equatorial energy transport is associated with a northward shift in the intertropical convergence zone. In the ocean, anomalous southward energy transport arises from a slowdown of the upper cell of the oceanic meridional overturning circulation and a weakening of the horizontal ocean gyres, causing sea ice in the Northern Hemisphere to expand and the Arctic to cool. Comparison with a slab-ocean simulation confirms the importance of ocean dynamics in determining the climate system response to Antarctic orography. This paper concludes by briefly presenting a discussion of the relevance of these results to climates of the past and to future climate scenarios.
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Weiffenbach, Julia E., Henk A. Dijkstra, Anna S. von der Heydt, Ayako Abe-Ouchi, Wing-Le Chan, Deepak Chandan, Ran Feng i in. "Highly stratified mid-Pliocene Southern Ocean in PlioMIP2". Climate of the Past 20, nr 4 (2.05.2024): 1067–86. http://dx.doi.org/10.5194/cp-20-1067-2024.
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Abstract. During the mid-Pliocene warm period (mPWP; 3.264–3.025 Ma), atmospheric CO2 concentrations were approximately 400 ppm, and the Antarctic Ice Sheet was substantially reduced compared to today. Antarctica is surrounded by the Southern Ocean, which plays a crucial role in the global oceanic circulation and climate regulation. Using results from the Pliocene Model Intercomparison Project (PlioMIP2), we investigate Southern Ocean conditions during the mPWP with respect to the pre-industrial period. We find that the mean sea surface temperature (SST) warming in the Southern Ocean is 2.8 °C, while global mean SST warming is 2.4 °C. The enhanced warming is strongly tied to a dramatic decrease in sea ice cover over the mPWP Southern Ocean. We also see a freshening of the ocean (sub)surface, driven by an increase in precipitation over the Southern Ocean and Antarctica. The warmer and fresher surface leads to a highly stratified Southern Ocean that can be related to weakening of the deep abyssal overturning circulation. Sensitivity simulations show that the decrease in sea ice cover and enhanced warming is largely a consequence of the reduction in the Antarctic Ice Sheet. In addition, the mPWP geographic boundary conditions are responsible for approximately half of the increase in mPWP SST warming, sea ice loss, precipitation, and stratification increase over the Southern Ocean. From these results, we conclude that a strongly reduced Antarctic Ice Sheet during the mPWP has a substantial influence on the state of the Southern Ocean and exacerbates the changes that are induced by a higher CO2 concentration alone. This is relevant for the long-term future of the Southern Ocean, as we expect melting of the western Antarctic Ice Sheet in the future, an effect that is not currently taken into account in future projections by Coupled Model Intercomparison Project (CMIP) ensembles.
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Kusahara, Kazuya, i Kay I. Ohshima. "Kelvin Waves around Antarctica". Journal of Physical Oceanography 44, nr 11 (1.11.2014): 2909–20. http://dx.doi.org/10.1175/jpo-d-14-0051.1.
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Abstract The Southern Ocean allows circumpolar structure and the Antarctic coastline plays a role as a waveguide for oceanic Kelvin waves. Under the cyclic conditions, the horizontal wavenumbers and frequencies for circumpolarly propagating waves are quantized, with horizontal wavenumbers 1, 2, and 3, corresponding to periods of about 32, 16, and 11 h, respectively. At these frequencies, westward-propagating signals are detected in sea level variation observed at Antarctic coastal stations. The occurrence frequency of westward-propagating signals far exceeds the statistical significance, and the phase speed of the observed signal agrees well with the theoretical phase speed of external Kelvin waves. Therefore, this study concludes that the observed, westward-propagating sea level variability is a signal of the external Kelvin waves of wavenumbers 1, 2, and 3 around Antarctica. A series of numerical model experiments confirms that Kelvin waves around Antarctica are driven by surface air pressure and that these waves are excited not only by local forcing over the Southern Ocean, but also by remote forcing over the Pacific Ocean. Sea level variations generated over the Pacific Ocean can travel to the western side of the South American coast and cross over Drake Passage to the Antarctic continent, constituting a part of the Kelvin waves around Antarctica.
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Lee, Sara, Wooseok Oh, Hyoung Sul La, Wuju Son, Jeong-Hoon Kim i Kyounghoon Lee. "Spatiotemporal Distribution of Antarctic Silverfish in the Ross Sea, Antarctica". Fishes 9, nr 2 (26.01.2024): 47. http://dx.doi.org/10.3390/fishes9020047.
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Antarctic silverfish (Pleuragramma antarcticum) play a crucial intermediary role in connecting top predators and krill in the food web of the Antarctic Ocean. Despite their crucial role, research on their abundance is lacking. In this study, we estimated the abundance of juvenile Antarctic silverfish as foundational data for predicting their abundance. The density of juvenile Antarctic silverfish was estimated using an acoustic backscattering theoretical model. The mean volume backscattering strength was used to investigate the vertical and horizontal distributions of juvenile Antarctic silverfish in the Antarctic Ross Sea. The survey area was located near Cape Hallett, Antarctica, where Antarctic krill (Euphausia superba), ice krill (E. crystallorophias), and Antarctic silverfish coexist. The survey was performed four times using the Korean Antarctic research ship, RV Araon (R/V, 7507 GT). Frame trawls were conducted to identify the length and weight of the target fish species in the survey area. Captured Antarctic silverfish captured measured 3–9 cm. The maximum target strength (TS) was −92.93 dB at 38 kHz, −86.63 dB at 120 kHz, and 85.89 dB at 200 kHz. The average TS was −100.00 dB at 38 kHz, −93.00 dB at 120 kHz, and −106.90 dB at 200 kHz. Most juvenile Antarctic silverfish were found at a depth of 100 m and were distributed closer to sea ice. Between nearshore and polynya waters, the fish demonstrated a proclivity for polynya waters.
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Wang, Caixin, i Aike Beckmann. "Investigation of the impact of Antarctic ice-shelf melting in a global ice–ocean model (ORCA2-LIM)". Annals of Glaciology 46 (2007): 78–82. http://dx.doi.org/10.3189/172756407782871602.
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AbstractIce-shelf melting (ISM) removes heat from and injects fresh water into the adjacent ocean and contributes significantly to the freshwater balance and water mass formation in the Antarctic marginal seas. The thermodynamic interaction between ocean and ice shelf is a complicated process and usually not adequately included in the ocean–ice climate models. In this paper, the ISM from all major ice-shelf areas around Antarctica is added to a global coupled ice–ocean model ORCA2-LIM following the parameterization proposed by Beckmann and Goosse (2003). Using interannual forcing data from 1958 through 2000, the impact of ISM on Southern Ocean hydrography and sea-ice distribution is investigated. The model also shows global signatures of the Antarctic ISM.
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Ma, Hao, i Lixin Wu. "Global Teleconnections in Response to Freshening over the Antarctic Ocean". Journal of Climate 24, nr 4 (15.02.2011): 1071–88. http://dx.doi.org/10.1175/2010jcli3634.1.
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Abstract In this paper, coupled ocean–atmosphere responses to freshening over the Antarctic Ocean are investigated in a fully coupled model with a series of sensitivity experiments. In the model, 1.0 Sv (1 Sv ≡ 106 m3 s−1) of freshwater flux is uniformly imposed over the Antarctic Ocean for 400 yr, while the ocean and atmosphere remain fully coupled both locally and elsewhere. The model explicitly demonstrates that a freshening of the Antarctic Ocean can induce a significant local cooling coupled with an intensification of the westerly winds and expansion of sea ice. Furthermore, the cooling can extend to the entire southern extratropical and tropical oceans coupled with an intensification of southeasterly trades and the equatorial trade winds. Some modest warm anomalies also occur in the northern extratropical oceans, forming a sharp interhemispheric SST contrast. A series of sensitivity experiments are conducted to understand the mechanisms responsible for transmitting the southern high latitude cooling to the tropics and the Northern Hemisphere. Experimental results demonstrate the important role of the surface coupled wind–evaporation–SST feedback and in turn changes of the subtropical–tropical meridional overturning circulation in conveying the southern high-latitude temperature anomalies to the tropics. The interhemispheric seesaw originates from the tropical–northern extratropical atmospheric teleconnection and is sustained by the subductive process of Antarctic subsurface warming. The Atlantic meridional overturning circulation is intensified in the first few decades of the freshwater forcing over the Antarctic Ocean because of a shutdown of the Antarctic deep convection, but it subsequently decreases because of the spreading of the fresh anomalies from the Southern Ocean to the Northern Ocean.
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Swart, Neil C., Torge Martin, Rebecca Beadling, Jia-Jia Chen, Christopher Danek, Matthew H. England, Riccardo Farneti i in. "The Southern Ocean Freshwater Input from Antarctica (SOFIA) Initiative: scientific objectives and experimental design". Geoscientific Model Development 16, nr 24 (19.12.2023): 7289–309. http://dx.doi.org/10.5194/gmd-16-7289-2023.
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Abstract. As the climate warms, the grounded ice sheet and floating ice shelves surrounding Antarctica are melting and releasing additional freshwater into the Southern Ocean. Nonetheless, almost all existing coupled climate models have fixed ice sheets and lack the physics required to represent the dominant sources of Antarctic melt. These missing ice dynamics represent a key uncertainty that is typically unaccounted for in current global climate change projections. Previous modelling studies that have imposed additional Antarctic meltwater have demonstrated regional impacts on Southern Ocean stratification, circulation, and sea ice, as well as remote changes in atmospheric circulation, tropical precipitation, and global temperature. However, these previous studies have used widely varying rates of freshwater forcing, have been conducted using different climate models and configurations, and have reached differing conclusions on the magnitude of meltwater–climate feedbacks. The Southern Ocean Freshwater Input from Antarctica (SOFIA) initiative brings together a team of scientists to quantify the climate system response to Antarctic meltwater input along with key aspects of the uncertainty. In this paper, we summarize the state of knowledge on meltwater discharge from the Antarctic ice sheet and ice shelves to the Southern Ocean and explain the scientific objectives of our initiative. We propose a series of coupled and ocean–sea ice model experiments, including idealized meltwater experiments, historical experiments with observationally consistent meltwater input, and future scenarios driven by meltwater inputs derived from stand-alone ice sheet models. Through coordinating a multi-model ensemble of simulations using a common experimental design, open data archiving, and facilitating scientific collaboration, SOFIA aims to move the community toward better constraining our understanding of the climate system response to Antarctic melt.
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Li, Xichen, David M. Holland, Edwin P. Gerber i Changhyun Yoo. "Rossby Waves Mediate Impacts of Tropical Oceans on West Antarctic Atmospheric Circulation in Austral Winter". Journal of Climate 28, nr 20 (13.10.2015): 8151–64. http://dx.doi.org/10.1175/jcli-d-15-0113.1.
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Abstract Recent studies link climate change around Antarctica to the sea surface temperature of tropical oceans, with teleconnections from the Pacific, Atlantic, and Indian Oceans making different contributions to Antarctic climate. In this study, the impacts of each ocean basin on the wintertime Southern Hemisphere circulation are identified by comparing simulation results using a comprehensive atmospheric model, an idealized dynamical core model, and a theoretical Rossby wave model. The results herein show that tropical Atlantic Ocean warming, Indian Ocean warming, and eastern Pacific cooling are all able to deepen the Amundsen Sea low located adjacent to West Antarctica, while western Pacific warming increases the pressure to the west of the international date line, encompassing the Ross Sea and regions south of the Tasman Sea. In austral winter, these tropical ocean basins work together linearly to modulate the atmospheric circulation around West Antarctica. Further analyses indicate that these teleconnections critically depend on stationary Rossby wave dynamics and are thus sensitive to the background flow, particularly the subtropical/midlatitude jet. Near these jets, wind shear is amplified, which strengthens the generation of Rossby waves. On the other hand, near the edges of the jets the meridional gradient of the absolute vorticity is also enhanced. As a consequence of the Rossby wave dispersion relationship, the jet edge may reflect stationary Rossby wave trains, serving as a waveguide. The simulation results not only identify the relative roles of each of the tropical ocean basins in the tropical–Antarctica teleconnection, but also suggest that a deeper understanding of teleconnections requires a better estimation of the atmospheric jet structures.
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Kriwoken, Lorne K., i John W. Williamson. "Hobart, Tasmania: Antarctic and Southern Ocean connections". Polar Record 29, nr 169 (kwiecień 1993): 93–102. http://dx.doi.org/10.1017/s0032247400023548.
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abstractThis paper describes the historical and contemporary associations between Hobart (Tasmania, Australia) and Antarctica and the Southern Ocean. This association is traced from the sealing and whaling industry, through early exploration and scientific expeditions, to contemporary issues of institutional and educational development and tourism. I is argued that this polar link has placed Hobart at the centre of some important Antarctic and Southern Ocean developments.
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Long, Douglas J. "Quaternary colonization or Paleogene persistence?: historical biogeography of skates (Chondrichthyes: Rajidae) in the Antarctic ichthyofauna". Paleobiology 20, nr 2 (1994): 215–28. http://dx.doi.org/10.1017/s0094837300012690.
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Seven endemic species of skates (Chondrichthyes: Rajidae) represent the only family of elasmobranchs currently known to live in Antarctic continental waters. Many previous authors believed skates colonized Antarctic waters from Patagonia during interglacial periods in the Quaternary. However, recent fossil material collected from the middle Eocene La Meseta Formation of Seymour Island, Antarctic Peninsula, indicates that they may have persisted in Antarctic waters since the Paleogene. Additionally, oceanographic barriers present in the Neogene and Quaternary would have prevented dispersal from southern continents to Antarctica. A revised dispersal scenario, based on skate fossils, biology, paleogeography, and present centers of skate diversity, suggests that skates evolved in the western Tethys and North Boreal seas of western Europe in the Late Cretaceous and early Paleogene and emigrated into Antarctica during the early to middle Eocene via a dispersal corridor along the continental margins of the western Atlantic Ocean. Skates probably populated the Pacific Basin by passing from this dispersal corridor through the Arctic Ocean. Vicariant events, such as opening of the Drake Passage, the development of the Circum-Antarctic Current, and formation of deep and wide basins around Antarctica in the late Paleogene, created barriers that isolated some species of skates in Antarctica and prevented movement of other species of skates into Antarctica from northern areas. Skates are the only group of fishes known to have survived the Oligocene cooling of Antarctica that killed or extirpated the Paleogene ichthyofauna; they persisted by a combination of cold-tolerance, generalized diet, and unspecialized bathymetric and habitat preferences.
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Yu, Lejiang, Shiyuan Zhong i Bo Sun. "The Climatology and Trend of Surface Wind Speed over Antarctica and the Southern Ocean and the Implication to Wind Energy Application". Atmosphere 11, nr 1 (16.01.2020): 108. http://dx.doi.org/10.3390/atmos11010108.
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Surface wind trends and variability over Antarctica and the Southern Ocean and their implications to wind energy in the region are analyzed using the gridded ERA-Interim reanalysis data between 1979 and 2017 and the Self-Organizing Map (SOM) technique. In general, surface winds are stronger over the coastal regions of East Antarctica and the Transantarctic Mountains and weaker over the Ross and Ronne ice shelves and the Antarctic Peninsula; and stronger in winter and weaker in summer. Winds in the southern Indian and Pacific Oceans and along coastal regions exhibit a strong interannual variability that appears to be correlated to the Antarctic Oscillation (AAO) index. A significantly positive trend in surface wind speeds is found across most regions and about 20% and 17% of the austral autumn and summer wind trends, respectively, and less than 1% of the winter and spring wind trends may be explained by the trends in the AAO index. Except for the Antarctic Peninsula, Ronne and Ross ice shelves, and small areas in the interior East Antarctica, most of the continent is found to be suitable for the development of wind power.
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Yusof, Nur Athirah, Makdi Masnoddin, Jennifer Charles, Ying Qing Thien, Farhan Nazaie Nasib, Clemente Michael Vui Ling Wong, Abdul Munir Abdul Murad, Nor Muhammad Mahadi i Izwan Bharudin. "Can heat shock protein 70 (HSP70) serve as biomarkers in Antarctica for future ocean acidification, warming and salinity stress?" Polar Biology 45, nr 3 (24.01.2022): 371–94. http://dx.doi.org/10.1007/s00300-022-03006-7.
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AbstractThe Antarctic Peninsula is one of the fastest-warming places on Earth. Elevated sea water temperatures cause glacier and sea ice melting. When icebergs melt into the ocean, it “freshens” the saltwater around them, reducing its salinity. The oceans absorb excess anthropogenic carbon dioxide (CO2) causing decline in ocean pH, a process known as ocean acidification. Many marine organisms are specifically affected by ocean warming, freshening and acidification. Due to the sensitivity of Antarctica to global warming, using biomarkers is the best way for scientists to predict more accurately future climate change and provide useful information or ecological risk assessments. The 70-kilodalton (kDa) heat shock protein (HSP70) chaperones have been used as biomarkers of stress in temperate and tropical environments. The induction of the HSP70 genes (Hsp70) that alter intracellular proteins in living organisms is a signal triggered by environmental temperature changes. Induction of Hsp70 has been observed both in eukaryotes and in prokaryotes as response to environmental stressors including increased and decreased temperature, salinity, pH and the combined effects of changes in temperature, acidification and salinity stress. Generally, HSP70s play critical roles in numerous complex processes of metabolism; their synthesis can usually be increased or decreased during stressful conditions. However, there is a question as to whether HSP70s may serve as excellent biomarkers in the Antarctic considering the long residence time of Antarctic organisms in a cold polar environment which appears to have greatly modified the response of heat responding transcriptional systems. This review provides insight into the vital roles of HSP70 that make them ideal candidates as biomarkers for identifying resistance and resilience in response to abiotic stressors associated with climate change, which are the effects of ocean warming, freshening and acidification in Antarctic organisms.
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Yamagata, Hirokazu, Shuma Kochii, Hiroshi Yoshida, Yoshifumi Nogi i Toshihiro Maki. "Development of AUV MONACA - Hover-Capable Platform for Detailed Observation Under Ice –". Journal of Robotics and Mechatronics 33, nr 6 (20.12.2021): 1223–33. http://dx.doi.org/10.20965/jrm.2021.p1223.
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The melting of ice and changes in ocean currents in Antarctica must be investigated to understand global climate change. In this regard, the volume changes of sea ice and ice shelves, bathymetry, and ocean currents in the Antarctic Ocean must be measured in three dimensions. Therefore, the use of autonomous underwater vehicles (AUVs), which can directly observe under ice, is being considered. The authors developed an AUV named Mobility Oriented Nadir AntarctiC Adventurer (MONACA) to observe sea ice and the lower region of the ice shelf in the Antarctic Ocean. Herein, we describe MONACA and its basic autonomous navigation methods (altitude control, depth control, and waypoint tracking), as well as report the results of a sea experiment conducted in Shimoda Bay, Japan. During the 5-day sea trial, the MONACA successfully measured bathymetry by tracking 15 waypoints in sequence, switching the control criteria in the -axis direction between 3 m depth and 3 m altitude.
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Zhu, Chenyu, Jiaxu Zhang, Zhengyu Liu, Bette L. Otto-Bliesner, Chengfei He, Esther C. Brady, Robert Tomas i in. "Antarctic Warming during Heinrich Stadial 1 in a Transient Isotope-Enabled Deglacial Simulation". Journal of Climate 35, nr 22 (15.11.2022): 3753–65. http://dx.doi.org/10.1175/jcli-d-22-0094.1.
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Abstract Heinrich Stadial 1 (HS1) was the major climate event at the onset of the last deglaciation associated with rapid cooling in Greenland and lagged, slow warming in Antarctica. Although it is widely believed that temperature signals were triggered in the Northern Hemisphere and propagated southward associated with the Atlantic meridional overturning circulation (AMOC), understanding how these signals were able to cross the Antarctic Circumpolar Current (ACC) barrier and further warm up Antarctica has proven particularly challenging. In this study, we explore the physical processes that lead to the Antarctic warming during HS1 in a transient isotope-enabled deglacial simulation iTRACE, in which the interpolar phasing has been faithfully reproduced. We show that the increased meridional heat transport alone, first through the ocean and then through the atmosphere, can explain the Antarctic warming during the early stage of HS1 without notable changes in the strength and position of the Southern Hemisphere midlatitude westerlies. In particular, when a reduction of the AMOC causes ocean warming to the north of the ACC, increased southward ocean heat transport by mesoscale eddies is triggered by steeper isopycnals to warm up the ocean beyond the ACC, which further decreases the sea ice concentration and leads to more absorption of insolation. The increased atmospheric heat then releases to the Antarctic primarily by a strengthening zonal wavenumber-3 (ZW3) pattern. Sensitivity experiments further suggest that a ∼4°C warming caused by this mechanism superimposed on a comparable warming driven by the background atmospheric CO2 rise is able to explain the total simulated ∼8°C warming in the West Antarctica during HS1.
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Muñoz-Ramírez, Carlos P., David K. A. Barnes, Leyla Cárdenas, Michael P. Meredith, Simon A. Morley, Alejandro Roman-Gonzalez, Chester J. Sands, James Scourse i Antonio Brante. "Gene flow in the Antarctic bivalve Aequiyoldia eightsii (Jay, 1839) suggests a role for the Antarctic Peninsula Coastal Current in larval dispersal". Royal Society Open Science 7, nr 9 (wrzesień 2020): 200603. http://dx.doi.org/10.1098/rsos.200603.
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The Antarctic Circumpolar Current (ACC) dominates the open-ocean circulation of the Southern Ocean, and both isolates and connects the Southern Ocean biodiversity. However, the impact on biological processes of other Southern Ocean currents is less clear. Adjacent to the West Antarctic Peninsula (WAP), the ACC flows offshore in a northeastward direction, whereas the Antarctic Peninsula Coastal Current (APCC) follows a complex circulation pattern along the coast, with topographically influenced deflections depending on the area. Using genomic data, we estimated genetic structure and migration rates between populations of the benthic bivalve Aequiyoldia eightsii from the shallows of southern South America and the WAP to test the role of the ACC and the APCC in its dispersal. We found strong genetic structure across the ACC (between southern South America and Antarctica) and moderate structure between populations of the WAP. Migration rates along the WAP were consistent with the APCC being important for species dispersal. Along with supporting current knowledge about ocean circulation models at the WAP, migration from the tip of the Antarctic Peninsula to the Bellingshausen Sea highlights the complexities of Southern Ocean circulation. This study provides novel biological evidence of a role of the APCC as a driver of species dispersal and highlights the power of genomic data for aiding in the understanding of the influence of complex oceanographic processes in shaping the population structure of marine species.
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Greco, Samuele, Giacomo Voltarel, Anastasia Serena Gaetano, Chiara Manfrin, Alberto Pallavicini, Piero Giulio Giulianini i Marco Gerdol. "Comparative Transcriptomic Analysis Reveals Adaptive Traits in Antarctic Scallop Adamussium colbecki". Fishes 8, nr 6 (23.05.2023): 276. http://dx.doi.org/10.3390/fishes8060276.
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Antarctica is the most extreme continent of Earth, with strong winds, freezing temperatures on land, and ocean temperatures constantly below 0 °C. Nonetheless, the Antarctic Ocean is home to an astounding diversity of living organisms that adapted to the multiple challenges posed by this environment via a diverse set of evolutionary traits. Although the recent advancements in sequencing technologies clarified the molecular bases of such adaptations in Antarctic fishes, little information is available for Antarctic invertebrates. In this preliminary study, we address this knowledge gap with a comparative transcriptomic approach to obtain insights into some of the adaptations that allow the Antarctic scallop Adamussium colbecki to survive and thrive in the freezing waters of the Antarctic Ocean. Despite some limitations, our analyses highlighted significant over-expression of genes involved in regulation of mRNA transcription, maturation, and degradation, which might compensate for a reduced efficiency of these processes at low temperatures. Other alterations detected in the Antarctic scallop transcriptome include enhanced expression of genes that regulate degradation of misfolded protein products and allow maintenance of cytoskeletal structure and function at subzero temperatures. Altogether, these observations support the presence of multiple previously unreported molecular adaptive traits in A. colbecki, which have important implications for our understanding of adaptation of this important component of the Antarctic trophic chain to such an extreme, but stable environment.
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Deppeler, Stacy, Kai G. Schulz, Alyce Hancock, Penelope Pascoe, John McKinlay i Andrew Davidson. "Ocean acidification reduces growth and grazing impact of Antarctic heterotrophic nanoflagellates". Biogeosciences 17, nr 16 (18.08.2020): 4153–71. http://dx.doi.org/10.5194/bg-17-4153-2020.
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Abstract. High-latitude oceans have been identified as particularly vulnerable to ocean acidification if anthropogenic CO2 emissions continue. Marine microbes are an essential part of the marine food web and are a critical link in biogeochemical processes in the ocean, such as the cycling of nutrients and carbon. Despite this, the response of Antarctic marine microbial communities to ocean acidification is poorly understood. We investigated the effect of increasing fCO2 on the growth of heterotrophic nanoflagellates (HNFs), nano- and picophytoplankton, and prokaryotes (heterotrophic Bacteria and Archaea) in a natural coastal Antarctic marine microbial community from Prydz Bay, East Antarctica. At CO2 levels ≥634 µatm, HNF abundance was reduced, coinciding with increased abundance of picophytoplankton and prokaryotes. This increase in picophytoplankton and prokaryote abundance was likely due to a reduction in top-down control of grazing HNFs. Nanophytoplankton abundance was elevated in the 634 µatm treatment, suggesting that moderate increases in CO2 may stimulate growth. The taxonomic and morphological differences in CO2 tolerance we observed are likely to favour dominance of microbial communities by prokaryotes, nanophytoplankton, and picophytoplankton. Such changes in predator–prey interactions with ocean acidification could have a significant effect on the food web and biogeochemistry in the Southern Ocean, intensifying organic-matter recycling in surface waters; reducing vertical carbon flux; and reducing the quality, quantity, and availability of food for higher trophic levels.
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Halanych, Kenneth M., i Andrew R. Mahon. "Challenging Dogma Concerning Biogeographic Patterns of Antarctica and the Southern Ocean". Annual Review of Ecology, Evolution, and Systematics 49, nr 1 (2.11.2018): 355–78. http://dx.doi.org/10.1146/annurev-ecolsys-121415-032139.
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Antarctica is enormous, cold, remote, and particularly sensitive to climate change. Most biological research below 60°S has focused on the isolated nature of the biota and how organisms have adapted to the cold and ice. However, biogeographic patterns in Antarctica and the Southern Ocean, and the processes explaining how those patterns came about, still await adequate explanation. Both terrestrial and marine organisms have been influenced by climatic change (e.g., glaciation), physical phenomena (e.g., oceanic currents), and/or potential barriers to gene flow (e.g., steep thermal gradients). Whereas the Antarctic region contains diverse and complex marine communities, terrestrial systems tend to be comparatively simple with limited diversity. Here, we challenge the current dogma used to explain the diversity and biogeographic patterns present in the Antarctic. We assert that relatively modern processes within the last few million years, rather than geo-logical events that occurred in the Eocene and Miocene, account for present patterns of biodiversity in the region. Additionally, reproductive life history stages appear to have little influence in structuring genetic patterns in the Antarctic, as currents and glacial patterns are noted to be more important drivers of organismal patterns of distribution. Finally, we highlight the need for additional sampling, high-throughput genomic approaches, and broad, multinational cooperation for addressing outstanding questions of Antarctic biogeography and biodiversity.
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Kennicutt, M. C., S. L. Chown, J. J. Cassano, D. Liggett, L. S. Peck, R. Massom, S. R. Rintoul i in. "A roadmap for Antarctic and Southern Ocean science for the next two decades and beyond". Antarctic Science 27, nr 1 (18.09.2014): 3–18. http://dx.doi.org/10.1017/s0954102014000674.
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AbstractAntarctic and Southern Ocean science is vital to understanding natural variability, the processes that govern global change and the role of humans in the Earth and climate system. The potential for new knowledge to be gained from future Antarctic science is substantial. Therefore, the international Antarctic community came together to ‘scan the horizon’ to identify the highest priority scientific questions that researchers should aspire to answer in the next two decades and beyond. Wide consultation was a fundamental principle for the development of a collective, international view of the most important future directions in Antarctic science. From the many possibilities, the horizon scan identified 80 key scientific questions through structured debate, discussion, revision and voting. Questions were clustered into seven topics: i) Antarctic atmosphere and global connections, ii) Southern Ocean and sea ice in a warming world, iii) ice sheet and sea level, iv) the dynamic Earth, v) life on the precipice, vi) near-Earth space and beyond, and vii) human presence in Antarctica. Answering the questions identified by the horizon scan will require innovative experimental designs, novel applications of technology, invention of next-generation field and laboratory approaches, and expanded observing systems and networks. Unbiased, non-contaminating procedures will be required to retrieve the requisite air, biota, sediment, rock, ice and water samples. Sustained year-round access to Antarctica and the Southern Ocean will be essential to increase winter-time measurements. Improved models are needed that represent Antarctica and the Southern Ocean in the Earth System, and provide predictions at spatial and temporal resolutions useful for decision making. A co-ordinated portfolio of cross-disciplinary science, based on new models of international collaboration, will be essential as no scientist, programme or nation can realize these aspirations alone.
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Pugh, P. J. A. "Have mites (Acarina: Arachnida) colonised Antarctica and the islands of the Southern Ocean via air currents?" Polar Record 39, nr 3 (26.06.2003): 239–44. http://dx.doi.org/10.1017/s0032247403003097.
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Mites (Acarina: Arachnida) have not colonised Antarctica and the sub-Antarctic islands by ballooning on air currents. All acarine records from Pacific and Southern Ocean aerial plankton represent dead coastal (hemi)-edaphic species or phoretics dislodged from their flying insect hosts. The few sub-Antarctic records of mites capable of ‘ballooning’ on air currents are all verified as being attributed to anthropogenic introductions.
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Orbeim, Olav. "Icebergs in the Southern Ocean (Abstract)". Annals of Glaciology 9 (1987): 241–42. http://dx.doi.org/10.3189/s0260305500000793.
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Relatively little data on the distribution of Antarctic icebergs were available prior to 1980. The published literature included size data of about 5000 icebergs, and position data of 12 000 icebergs. There were indications that the size data were biased in favour of larger icebergs.A programme of systematic iceberg observations was therefore initiated by Norsk Polarinstitutt in 198! through the SCAR Working Group on Glaciology. This programme is based on standard “blue” forms distributed to all ships going to Antarctica. The icebergs are recorded every 6 h and in Five length groups: 10–50, 50–200, 200–500, and 500–1000 m, and those over 1000 m are described individually.The amount of data has increased greatly from the start in 1981–82. The position of 70 000 icebergs, including 50 000 that had been size classified, were on file at Norsk Polarinstitutt by December 1985, and the data set is growing rapidly. Most ships travelling to and from Antarctica now participate in collection of the data. (Fig.1 shows the locations of the icebergs sighted.) Fig. 1.Location of iceberg observations under the programme initiated in 1981. Main ship tracks are clearly reflected. The average observation represents 14 icebergs.The size distribution of the classified icebergs observed under this programme up to December 1985 is given in Table I: Table IThe “standard size” (length, width, and thickness) is based on our observations from three Antarctic expeditions which carried out dedicated iceberg studies. Many icebergs are of course not right-angled parallelepipedal in shape, but this is a good approximation for most of the larger icebergs.The data are based both on visual sightings and on radar observations. Duplicate observations from a ship moving at slow or zero speed are as far as possible eliminated, both during observation, and by critical appraisal before the data are filed. The data editing also includes evaluation of data quality, especially in connection with radar observations, and comparison of positions and dimensions of the large icebergs in order to reduce to a minimum repeated observations from different vessels of icebergs >1000 m. These account for most of the iceberg mass (see Table I).Consideration of iceberg-distribution patterns and the observed area of the Southern Ocean, and of duplicate observations, indicates more than 300 000 icebergs south of the Antarctic Convergence, with a total ice mass of about 1016 kg. Consideration of mean residence times indicates an annual iceberg production from the continent of 23–1015 kg, which is considerably higher than most other recent estimates. This also suggests that the Antarctic ice sheet is in balance.The data indicate large regional differences in iceberg sizes, the most noticeable being between the two sides of the Antarctic Peninsula, and between the Amery Ice Shelf/ Prydz Bay area and the remainder of East Antarctica. These differences are probably mainly related to different calving sites.About one-third of the observed icebergs are over the continental shelf of Antarctica. The total under-water area of these icebergs is two orders of magnitude less than the under-water area of the Antarctic ice shelves. The annual total iceberg melting and its effect on the water masses over the continental shelf has been calculated from ocean-water temperature variations at 200 m depth and estimated melt rates. This turns out to be an order of magnitude less than the annual effect of melting sea ice. The iceberg data considered here are probably under-represented with respect to the smallest sizes, and they do not include icebergs that have become <10 m. Inclusion of these ice bodies would increase the total melt.
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Orbeim, Olav. "Icebergs in the Southern Ocean (Abstract)". Annals of Glaciology 9 (1987): 241–42. http://dx.doi.org/10.1017/s0260305500000793.
Pełny tekst źródłaStreszczenie:
Relatively little data on the distribution of Antarctic icebergs were available prior to 1980. The published literature included size data of about 5000 icebergs, and position data of 12 000 icebergs. There were indications that the size data were biased in favour of larger icebergs. A programme of systematic iceberg observations was therefore initiated by Norsk Polarinstitutt in 198! through the SCAR Working Group on Glaciology. This programme is based on standard “blue” forms distributed to all ships going to Antarctica. The icebergs are recorded every 6 h and in Five length groups: 10–50, 50–200, 200–500, and 500–1000 m, and those over 1000 m are described individually. The amount of data has increased greatly from the start in 1981–82. The position of 70 000 icebergs, including 50 000 that had been size classified, were on file at Norsk Polarinstitutt by December 1985, and the data set is growing rapidly. Most ships travelling to and from Antarctica now participate in collection of the data. (Fig.1 shows the locations of the icebergs sighted.) Fig. 1. Location of iceberg observations under the programme initiated in 1981. Main ship tracks are clearly reflected. The average observation represents 14 icebergs. The size distribution of the classified icebergs observed under this programme up to December 1985 is given in Table I: Table I The “standard size” (length, width, and thickness) is based on our observations from three Antarctic expeditions which carried out dedicated iceberg studies. Many icebergs are of course not right-angled parallelepipedal in shape, but this is a good approximation for most of the larger icebergs. The data are based both on visual sightings and on radar observations. Duplicate observations from a ship moving at slow or zero speed are as far as possible eliminated, both during observation, and by critical appraisal before the data are filed. The data editing also includes evaluation of data quality, especially in connection with radar observations, and comparison of positions and dimensions of the large icebergs in order to reduce to a minimum repeated observations from different vessels of icebergs >1000 m. These account for most of the iceberg mass (see Table I). Consideration of iceberg-distribution patterns and the observed area of the Southern Ocean, and of duplicate observations, indicates more than 300 000 icebergs south of the Antarctic Convergence, with a total ice mass of about 1016 kg. Consideration of mean residence times indicates an annual iceberg production from the continent of 23–1015 kg, which is considerably higher than most other recent estimates. This also suggests that the Antarctic ice sheet is in balance. The data indicate large regional differences in iceberg sizes, the most noticeable being between the two sides of the Antarctic Peninsula, and between the Amery Ice Shelf/ Prydz Bay area and the remainder of East Antarctica. These differences are probably mainly related to different calving sites. About one-third of the observed icebergs are over the continental shelf of Antarctica. The total under-water area of these icebergs is two orders of magnitude less than the under-water area of the Antarctic ice shelves. The annual total iceberg melting and its effect on the water masses over the continental shelf has been calculated from ocean-water temperature variations at 200 m depth and estimated melt rates. This turns out to be an order of magnitude less than the annual effect of melting sea ice. The iceberg data considered here are probably under-represented with respect to the smallest sizes, and they do not include icebergs that have become <10 m. Inclusion of these ice bodies would increase the total melt.
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Turney, Chris S. M., Christopher J. Fogwill, Nicholas R. Golledge, Nicholas P. McKay, Erik van Sebille, Richard T. Jones, David Etheridge i in. "Early Last Interglacial ocean warming drove substantial ice mass loss from Antarctica". Proceedings of the National Academy of Sciences 117, nr 8 (11.02.2020): 3996–4006. http://dx.doi.org/10.1073/pnas.1902469117.
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The future response of the Antarctic ice sheet to rising temperatures remains highly uncertain. A useful period for assessing the sensitivity of Antarctica to warming is the Last Interglacial (LIG) (129 to 116 ky), which experienced warmer polar temperatures and higher global mean sea level (GMSL) (+6 to 9 m) relative to present day. LIG sea level cannot be fully explained by Greenland Ice Sheet melt (∼2 m), ocean thermal expansion, and melting mountain glaciers (∼1 m), suggesting substantial Antarctic mass loss was initiated by warming of Southern Ocean waters, resulting from a weakening Atlantic meridional overturning circulation in response to North Atlantic surface freshening. Here, we report a blue-ice record of ice sheet and environmental change from the Weddell Sea Embayment at the periphery of the marine-based West Antarctic Ice Sheet (WAIS), which is underlain by major methane hydrate reserves. Constrained by a widespread volcanic horizon and supported by ancient microbial DNA analyses, we provide evidence for substantial mass loss across the Weddell Sea Embayment during the LIG, most likely driven by ocean warming and associated with destabilization of subglacial hydrates. Ice sheet modeling supports this interpretation and suggests that millennial-scale warming of the Southern Ocean could have triggered a multimeter rise in global sea levels. Our data indicate that Antarctica is highly vulnerable to projected increases in ocean temperatures and may drive ice–climate feedbacks that further amplify warming.
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Massé, Guillaume, Simon T. Belt, Xavier Crosta, Sabine Schmidt, Ian Snape, David N. Thomas i Steven J. Rowland. "Highly branched isoprenoids as proxies for variable sea ice conditions in the Southern Ocean". Antarctic Science 23, nr 5 (27.06.2011): 487–98. http://dx.doi.org/10.1017/s0954102011000381.
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AbstractConcentrations of a highly branched isoprenoid (HBI) diene determined in over 200 sediment samples from the Arctic co-vary with those of an HBI monoene (IP25) shown previously to be a sedimentary sea ice proxy for the Arctic. The same diene, but not monoene IP25, occurred in nine sea ice samples collected from various locations around Antarctica. The diene has been reported previously in Antarctic sea ice diatoms and the 13C isotopic compositions of the diene determined in two Antarctic sea ice samples were also consistent with an origin from sea ice diatoms (δ13C -5.7 to -8.5‰). In contrast, HBIs found in two Antarctic phytoplankton samples did not include the diene but comprised a number of tri- to pentaenes. In sediment samples collected near Adélie Land, East Antarctica, both the diene and the tri- to pentaenes often co-occurred. 13C isotopic compositions of the tri- to pentaenes in three sediment samples ranged from -35 to -42‰ whereas that of the diene in a sediment sample was -18‰. We propose the presence of this isotopically 13C enriched HBI diene in Antarctic sediments to be a useful proxy indicator for contributions of organic matter derived from sea ice diatoms. A ratio of the concentrations of diene/trienes might reflect the relative contributions of sea ice to phytoplanktonic inputs of organic matter to Antarctic sediments.
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Shemesh, A., L. H. Burckle i P. N. Froelich. "Dissolution and Preservation of Antarctic Diatoms and the Effect on Sediment Thanatocoenoses". Quaternary Research 31, nr 2 (marzec 1989): 288–308. http://dx.doi.org/10.1016/0033-5894(89)90010-0.
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AbstractComparison of Southern Ocean diatom populations from (i) surface ocean production, (ii) underlying Antarctic sediments, and (iii) laboratory dissolution experiments demonstrates that dissolution can account for the temporal and spatial variations in sedimentary diatom assemblages observed in Southern Ocean sediments. Increasing dissolution causes relative depletions in N. kerguelensis (K), enrichments in T. lentiginosa (L), and slight enrichments in E. antarctica (A). This reflects the relative susceptibility to dissolution of the three species that dominate Antarctic sediments. We have devised a preservation index for the Southern Ocean based on the ratio K/(K + L) to estimate relative extents of dissolution and applied it to natural assemblages. Holocene Southern Ocean sediments display increasing opal preservation toward higher latitudes, but south of the Antarctic Polar Front preservation decreases in the order: well preserved = SE Indian > S. Atlantic ∼ SW Indian > SE Pacific = poorly preserved. Dissolution also accounts for the pattern of diatom assemblages in the last glacial maximum (LGM) sediments of the Indian and Pacific sectors, but in the Atlantic, increased E. antarctica abundances at LGM must have resulted from an increase in surface ocean production of this species. Holocene and LGM diatoms in Atlantic and Pacific sector sediments are equally well preserved, but in the Indian sectors, Holocene sediments are better preserved than those of LGM age. Paleoceanographic and paleoclimatic transfer functions derived from factor analyses of variations in the sedimentary abundances of these three diatoms have ignored the effects of differential dissolution on thanatocoenosis and thus should be interpreted with caution.
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Jacka, T. H. "Antarctic and Southern Ocean Sea-Ice and Climate Trends". Annals of Glaciology 14 (1990): 127–30. http://dx.doi.org/10.3189/s0260305500008417.
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A computer-based climate monitoring project is described. Data sets include monthly and annual mean surface temperatures and pressures for occupied stations in Antarctica, the Southern Ocean and South Pacific Ocean; and monthly Antarctic sea-ice extent at each 10° of longitude.Simple statistical analyses of the data sets reveal a mean warming of ~0.15°C (10 a)−1 since the mid 1950s for Antarctic coastal stations and of ~0.04°C (10 a)−1 since the mid 1940s for the ocean stations. The sea-ice record from 1973 to 1988 reveals that the average northern ice limit has decreased at ~0.23°lat. (10 a)−1. Despite apparently compatible long-term trends of temperature and sea-ice extent, annual fluctuations of temperature and ice extent are highly variable and are not well correlated.
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Jacka, T. H. "Antarctic and Southern Ocean Sea-Ice and Climate Trends". Annals of Glaciology 14 (1990): 127–30. http://dx.doi.org/10.1017/s0260305500008417.
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A computer-based climate monitoring project is described. Data sets include monthly and annual mean surface temperatures and pressures for occupied stations in Antarctica, the Southern Ocean and South Pacific Ocean; and monthly Antarctic sea-ice extent at each 10° of longitude. Simple statistical analyses of the data sets reveal a mean warming of ~0.15°C (10 a)−1 since the mid 1950s for Antarctic coastal stations and of ~0.04°C (10 a)−1 since the mid 1940s for the ocean stations. The sea-ice record from 1973 to 1988 reveals that the average northern ice limit has decreased at ~0.23°lat. (10 a)−1. Despite apparently compatible long-term trends of temperature and sea-ice extent, annual fluctuations of temperature and ice extent are highly variable and are not well correlated.
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Rubin, Jeff. "Train Oil and Snotters: Eating Antarctic Wild Foods". Gastronomica 3, nr 1 (2003): 37–57. http://dx.doi.org/10.1525/gfc.2003.3.1.37.
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People may no longer eat the wild foods of Antarctica, because the Antarctic Treaty's Protocol on Environmental Protection signed in 1991 prohibits even "disturbing" any wildlife, but there is a long history of living off the land in Antarctica and on the remote islands of the Southern Ocean. Visitors regularly ate seals, penguins and other seabirds, eggs, shellfish, and several unusual endemic plants. Fresh food was critical in avoiding scurvy, caused by a lack of Vitamin C. Local foods also occupied a prominent place on the table during Antarctic holidays such as Midwinter's Day.
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Jonkers, H. A. "Stratigraphy of Antarctic late Cenozoic pectinid-bearing deposits". Antarctic Science 10, nr 2 (czerwiec 1998): 161–70. http://dx.doi.org/10.1017/s0954102098000212.
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Antarctic late Cenozoic pectinid-bearing sedimentary strata are chiefly confined to localities in the northern part of the Antarctic Peninsula, in the McMurdo Sound area, and Marine Plain, East Antarctica. Ages of these deposits range from Oligocene to Holocene. Chlamys-like scallops, which are absent from today's Southern Ocean, thrived in Antarctic waters during both glacial and interglacial episodes, but disappeared during the Late Pliocene. Their extinction is believed to result from the combined effects of increased carbonate solubility, habitat loss and limitations in food availability, associated with major cooling.
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Markus, Thorsten, i Donald J. Cavalieri. "Interannual and regional variability of Southern Ocean snow on sea ice". Annals of Glaciology 44 (2006): 53–57. http://dx.doi.org/10.3189/172756406781811475.
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AbstractSnow depth on sea ice plays a critical role in the heat exchange between ocean and atmosphere because of its thermal insulation property. Furthermore, a heavy snow load on the relatively thin Southern Ocean sea-ice cover submerges the ice floes below sea level, causing snow-to-ice conversion. Snowfall is also an important freshwater source into the weakly stratified ocean. Snow-depth on sea-ice information can be used as an indirect measure of solid precipitation. Satellite passive microwave data are used to investigate the interannual and regional variability of the snow cover on sea ice. In this study we make use of 12 years (1992–2003) of Special Sensor Microwave/Imager (SSM/I) radiances to calculate average monthly snow depth on the Antarctic sea-ice cover. For the Antarctic sea-ice region as a whole, we find that September snow depth and sea-ice area are negatively correlated, which is not the case for individual regions. An analysis of the snow depth around Antarctica was undertaken. The results show an overall increase in snow depth for each of the five Antarctic sectors and the region as a whole, but only the Indian Ocean sector and the entire Southern Ocean show a statistically significant increase. There is a partial eastward propagation of maximum snow depths, which may be related to the Antarctic Circumpolar Wave. The overall trend and the variability of regional snow-depth distributions are also in agreement with cyclone density.
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Naughten, Kaitlin A., Katrin J. Meissner, Benjamin K. Galton-Fenzi, Matthew H. England, Ralph Timmermann i Hartmut H. Hellmer. "Future Projections of Antarctic Ice Shelf Melting Based on CMIP5 Scenarios". Journal of Climate 31, nr 13 (lipiec 2018): 5243–61. http://dx.doi.org/10.1175/jcli-d-17-0854.1.
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Basal melting of Antarctic ice shelves is expected to increase during the twenty-first century as the ocean warms, which will have consequences for ice sheet stability and global sea level rise. Here we present future projections of Antarctic ice shelf melting using the Finite Element Sea Ice/Ice-Shelf Ocean Model (FESOM) forced with atmospheric output from models from phase 5 of the Coupled Model Intercomparison Project (CMIP5). CMIP5 models are chosen based on their agreement with historical atmospheric reanalyses over the Southern Ocean; the best-performing models are ACCESS 1.0 and the CMIP5 multimodel mean. Their output is bias-corrected for the representative concentration pathway (RCP) 4.5 and 8.5 scenarios. During the twenty-first-century simulations, total ice shelf basal mass loss increases by between 41% and 129%. Every sector of Antarctica shows increased basal melting in every scenario, with the largest increases occurring in the Amundsen Sea. The main mechanism driving this melting is an increase in warm Circumpolar Deep Water on the Antarctic continental shelf. A reduction in wintertime sea ice formation simulated during the twenty-first century stratifies the water column, allowing a warm bottom layer to develop and intrude into ice shelf cavities. This effect may be overestimated in the Amundsen Sea because of a cold bias in the present-day simulation. Other consequences of weakened sea ice formation include freshening of High Salinity Shelf Water and warming of Antarctic Bottom Water. Furthermore, freshening around the Antarctic coast in our simulations causes the Antarctic Circumpolar Current to weaken and the Antarctic Coastal Current to strengthen.
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Heinrich, Katharina. "Biological Prospecting in Antarctica – A Solution-Based Approach to Regulating the Collection and Use of Antarctic Marine Biodiversity by Taking the BBNJ Process into Account". Yearbook of Polar Law Online 12, nr 1 (13.12.2021): 41–60. http://dx.doi.org/10.1163/22116427_012010005.
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Areas beyond national jurisdiction (ABNJ) are covering nearly two-thirds of the world’s oceans and are rich in biological diversity. These also include the Polar Regions, where marine organisms adapted to extreme environments and led to increased scientific interest and activities, including bioprospecting activities. As a result, marine biodiversity is increasingly threatened. Thus, the Convention on Biodiversity (CBD) was established to ensure the conservation and sustainable use of biodiversity but left ABNJ and bioprospecting activities widely unregulated. In Antarctica, for instance, bioprospecting has raised concerns, and the matter has been discussed since 2002. As a result, the United Nations General Assembly (UNGA) Resolution 69/292 concluded the establishment of a new international legally binding instrument (ILBI) on the conservation and sustainable use of marine biological diversity for ABNJ. However, the inclusion of the Antarctic Treaty Area remains unclear. In light of the current BBNJ negotiations, the Antarctic Treaty Consultative Meeting (ATCM) only acknowledges the Antarctic Treaty System (ATS) as the appropriate framework to regulate these activities in Antarctica. Further, it seems to aim for regulation under the ATS, if at all. Therefore, this paper discusses a solution-based approach for possible regulation of the collection and use of Antarctic marine biodiversity. The negotiations and achievements of the current BBNJ process will be taken into account, as they might provide support for the regulation of these issues in Antarctica and the Southern Ocean.
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Olshtynska, Olexandra P., i Stanislav P. Olshtynsky. "PETRO FEODOSIIOVYCH GOZHYK: OCEANIC, MARINE AND ANTARCTIC RESEARCH". Collection of Scientific Works of the Institute of Geological Sciences of the NAS of Ukraine 14, nr 1 (20.05.2021): 17–25. http://dx.doi.org/10.30836/igs.2522-9753.2021.228225.
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The article provides a brief overview of the publications, as well as our own memories about the doctor of geological and mineral sciences, Academician Petro Feodosiiovych Gozhyk — scientist, researcher that had state- and strategic level thinking, about his contribution to the development of marine geological works in the Institute of Geological Sciences of the National Academy of Sciences of Ukraine, his role in the creation of the Ukrainian Antarctic Center (nowadays the National Antarctic Research Center of The National Academy of Sciences of Ukraine) and the importance of his personality for the formation of Ukraine as «Antarctic State». P.F. Gozhyk was not only one of the initiators of the Center for Antarctic Research of the National Academy of Sciences of Ukraine, but also its first director, the developer of long-term polar research programs at the station «Academician Vernadsky». His scientific interests were focused on a wide range of subjects, and marine geology was among his scientific priorities. Academician P. F. Gozhyk was an organizer and participant of many round-the-world sea and ocean expeditions to the Indian, Atlantic and Southern oceans, the Red and Black Seas. The main publications of P. F. Gozhyk on «geology of the seas and oceans» and «geological studies of Antarctica» are listed in the article.
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Irving, E. G., i George Deacon. "The Antarctic Circumpolar Ocean". Geographical Journal 151, nr 3 (listopad 1985): 391. http://dx.doi.org/10.2307/633034.
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Banner, F. T. "The Antarctic circumpolar ocean". Endeavour 9, nr 2 (styczeń 1985): 109. http://dx.doi.org/10.1016/0160-9327(85)90063-8.
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Kinne, Otto. "The Antarctic Circumpolar Ocean". Interdisciplinary Science Reviews 10, nr 4 (styczeń 1985): 377. http://dx.doi.org/10.1179/isr.1985.10.4.377.
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