Antarctic Science最新文献

In March 1912, Captain Robert Falcon Scott and his companions perished on their return journey from the South Pole. The Final Blizzard delivered a terminal blow. However, it was only a part of this story of endurance and tragedy. In December 1911, en route to the South Pole, the men had been tent-bound for 4 days due to an exceptionally warm, wet blizzard. This article compares the meteorological situation that the polar party encountered in December 1911 to a similar situation in the modern time and suggests a possible climatology behind the 1911 event.

Due to the limited landmasses in the Southern Hemisphere, we must rely on data from sub-Antarctic islands within the Southern Ocean to record historical climate patterns. Over the past few decades, glaciers throughout the Southern Ocean region have experienced a noticeable retreat, especially in the Kerguelen Archipelago, whose glacial landforms offer valuable insights into long-term climate fluctuations. Our comprehensive glacial geomorphological study conducted in its remote north-western region meticulously examines morainic complexes from smaller cirque glaciers and larger outlet glaciers stemming from the Cook Ice Cap. We mapped these landforms to reconstruct historical glacier extents during the Holocene. The surface area of the three main glaciers had decreased in 1962–1964 by only 35% compared to their maximum extents, whereas surface area changes across 12 time intervals spanning from 1962 to 2019 from aerial and satellite imagery reveal a cumulative reduction of 43.5%. Additionally, we modelled changes in glacier thickness and equilibrium-line altitude for the key glaciers at three distinct stages: 1) their maximum extent before 1962, 2) the early 1960s and 3) 2019. This multifaceted analysis contributes valuable insights into the dynamics of Kerguelen's glaciers and the broader implications for understanding past and ongoing climate dynamics in the Southern Hemisphere.

We investigate two ice rises, Kupol Moskovskij and Kupol Ciolkovskogo, in the Fimbul Ice Shelf, East Antarctica, situated ~60 km from each other but differing in their glaciological settings. We apply a thermo-mechanically coupled Elmer/Ice model to profiles going across these ice rises and use it to investigate their past evolution covering present to several millennia ago. We constrain the model results using field measurements, including surface-velocity measurements, and surface mass balance estimated by isochronous radar stratigraphy dated with firn cores. We find that the ice rises are thickening at present (2012–2014), which started only in recent decades. Investigation of deeper radar reflectors suggests a stronger upwind-downwind contrast in surface mass balance in the past for both ice rises, with varying details. This result matches what was previously found on Blåskimen Island ice rise, which is also in the Fimbul Ice Shelf. Moreover, Kupol Moskovskij, situated at a shear margin, shows signs of recent changes in its ice-divide position, while Kupol Ciolkovskogo shows a more stable divide position. This study highlights the long-term influence of surface mass balance on ice rises, as well as the strong influence of local glaciological settings on their evolution.

Large-scale geological structures have controlled the long-term development of the bed and thus the flow of the West Antarctic Ice Sheet (WAIS). However, complete ice cover has obscured the age and exact positions of faults and geological boundaries beneath Thwaites Glacier and Pine Island Glacier, two major WAIS outlets in the Amundsen Sea sector. Here, we characterize the only rock outcrop between these two glaciers, which was exposed by the retreat of slow-flowing coastal ice in the early 2010s to form the new Sif Island. The island comprises granite, zircon U-Pb dated to ~177–174 Ma and characterized by initial ɛNd, 87Sr/86Sr and ɛHf isotope compositions of -2.3, 0.7061 and -1.3, respectively. These characteristics resemble Thurston Island/Antarctic Peninsula crustal block rocks, strongly suggesting that the Sif Island granite belongs to this province and placing the crustal block's boundary with the Marie Byrd Land province under Thwaites Glacier or its eastern shear margin. Low-temperature thermochronological data reveal that the granite underwent rapid cooling following emplacement, rapidly cooled again at ~100–90 Ma and then remained close to the Earth's surface until present. These data help date vertical displacement across the major tectonic structure beneath Pine Island Glacier to the Late Cretaceous.

Dermatofibroma is a commonly occurring cutaneous entity usually centered within the skin's dermis. Dermatofibromas are referred to as benign fibrous histiocytomas of the skin, superficial/cutaneous benign fibrous histiocytomas, or common fibrous histiocytoma. These mesenchymal cell lesions of the dermis clinically are firm subcutaneous nodules that occur on the extremities in the vast majority of cases and may or may not be associated with overlying skin changes. A 20 years old male presented to ENT OPD, at a private hospital, with complaints of a huge mass over right side of face since 15 years, which was slowly growing and not associated with pain. On clinical examination, hard, non tender, lobulated cauliflower like mass located over right side of face extending from right side temporal region to upper border of mandible from superior to inferior. From anterior to posterior it was extending from lateral 1/3rd of forehead and covering lateral canthus of right eye upto right side tragus. We have taken incisional biopsy which was suggestive of dermatofibroma. Then surgery was performed with patient's consent. Excision with 1 cm free margin was done. Raw area was covered with full thickness skin grafting and advancement flap. We found no recurrence till date. Dermatofibroma in the head and neck region is less common and often present a difficult differential diagnosis like Dermatofibrosarcoma protuberans, Kaposi Sarcoma, Basal cell carcinomas. The aim of case report is to represent case of dermatofibroma of epitheloid variety which is unusual in size.

A proportion of the southern elephant seal (Mirounga leonina) population that breeds in the Kerguelen Plateau region seasonally migrates between their natal sub-Antarctic islands and moult haul-out locations on the Antarctic coastline. Analyses of survey data collated for one moult location at the Vestfold Hills, East Antarctica, showed that there had been no appreciable change in the timing (phenology) of maximum seal arrivals between 1974 and 2022; however, the maximum number of seals moulting at that site had declined by ~90% over the same time interval. Spatial analyses showed rates of population change were survey area dependent, as seal numbers decreased most rapidly at haul-out areas closest to the permanently occupied Davis Station, suggesting that a relationship exists between seal numbers and human activities. The range of potential factors that contribute to population change for southern elephant seals moulting at the Vestfold Hills includes changes in status at primary source populations, one of which has not been surveyed since the 1990s, and species relocation. Should numbers of southern elephant seals in the Vestfold Hills continue to decrease at the current average rate of change (-7.78 seals/year) the species could vanish from the area by c. 2040.

Species distributions are predicted to change with future climate-associated ecosystem changes such that so-called ‘vagrant’ individuals may become established or re-establish in areas currently thought to be beyond their principle ranges. Survey data were collated for occurrences of pinniped (seal) species at very high latitudes of the Vestfold Hills, East Antarctica. Aside from Weddell seals (Leptonychotes weddellii) and southern elephant seals (Mirounga leonina), which aggregate annually at the Vestfold Hills to breed and/or moult, three other pinniped species were observed with the recession of the fast-ice edge. Leopard seal (Hydrurga leptonyx) occurrences increased with an increase in a seasonally abundant prey resource, and crabeater seals (Lobodon carcinophaga) were seen at a time that coincides with their moult period. Occurrences of sub-adult male Antarctic fur seals (Arctocephalus gazella) increase the known southward range for this species and may reflect population increases at source populations in the Kerguelen Plateau area. Although there were no direct sightings of Ross seals (Ommatophoca rossii), their presence close to the Vestfold Hills was detected by underwater passive acoustic monitoring. Sightings of obligate drift-ice species and sub-Antarctic fur seals may change at the Vestfold Hills with climate-mediated changes in sea-ice conditions.