A pair of juvenile emperor penguins (Aptenodytes forsteri) was observed in the northern coast of James Ross Island, the north-western sector of the Weddell Sea, Antarctica, in January 2017. The ...penguins originated from the colony located on Snow Hill Island, 120-130 km far from the observation area. Despite the emperor penguin´s ability to migrate over long distances, when they are well-known from different areas in Antarctica, this was the first observation of this species in the north of James Ross Island. In this short paper we discuss the environmental factors which allowed the penguins to reach James Ross Island northern coast, especially significant sea ice variability in this area during last decade.
Permafrost is present within almost all of the Antarctic's ice-free areas,
but little is known about spatial variations in permafrost temperatures
except for a few areas with established ground ...temperature measurements. We
modelled a temperature at the top of the permafrost (TTOP) for all the
ice-free areas of the Antarctic mainland and Antarctic islands at 1 km2
resolution during 2000–2017. The model was driven by remotely sensed land
surface temperatures and downscaled ERA-Interim climate reanalysis data, and
subgrid permafrost variability was simulated by variable snow cover. The
results were validated against in situ-measured ground temperatures from 40
permafrost boreholes, and the resulting root-mean-square error was
1.9 ∘C. The lowest near-surface permafrost temperature of
−36 ∘C was modelled at Mount Markham in the Queen Elizabeth Range in
the Transantarctic Mountains. This is the lowest permafrost temperature on
Earth, according to global-scale modelling results. The temperatures were
most commonly modelled between −23 and −18 ∘C for mountainous
areas rising above the Antarctic Ice Sheet and between −14 and −8 ∘C for coastal areas. The model performance was good where snow
conditions were modelled realistically, but errors of up to 4 ∘C
occurred at sites with strong wind-driven redistribution of snow.
The active layer thermal regime was studied at two sites with different lithological properties located on James Ross Island, eastern Antarctic Peninsula, to assess the main driving factors. The ...Abernethy Flats site (41ma.s.l.) is located in Cretaceous calcareous sandstones and siltstones of the Santa Marta Formation. In contrast, the Berry Hill slopes site (56m) is composed of muddy to intermediate diamictites, tuffaceous siltstones to fine-grained sandstones of the Mendel Formation. The data of air temperature at 2m and ground temperature at two 75-cm-deep profiles were analysed for the period 1 January 2012, to 31 December 2014. Small differences were found when comparing mean air temperatures and ground temperatures at 5, 50 and 75cm depths, in the period 2012–2014. While the mean air temperatures varied between −7.7°C and −7.0°C, the average ground temperatures oscillated between −6.6°C and −6.1°C at 5cm; −6.7°C and −6.0°C at 50cm; and −6.9°C and −6.0°C at 75cm at Abernethy Flats and Berry Hill slopes, respectively. The increasing difference of ground temperature with depth, and a significant difference in active layer thickness – 52 to 64cm at Abernethy Flats and 85 to 90cm at Berry Hill slopes, respectively – suggests the significant effect of lithology. The higher proportion of fine particles and more thermally conductive minerals, together with higher water saturation, has been found to be fundamental for higher active layer thickness documented at Berry Hill slopes.
•Active layer thermal regime at two sites on James Ross Island was studied.•Three years of air and ground temperature measurements were analysed.•Lithology significantly affects active layer thermal regime and thickness.•Active layer thickness ranged from 52 to 90cm in period 2012 to 2014.•Effect of air temperature on ground temperature was similar at both sites.
•In Antarctica summer Ground Surface Temperature (GST) is not correlated with latitude.•Incoming radiation is the main driver of summer GST.•Active Layer Thickness (ALT) and summer GST are completely ...decoupled.•The effect of moss cover on GST and ALT is species-specific.•Moss structure and water retention capacity are crucial for ALT.
Ground surface temperature (GST) and active layer thickness (ALT) are key indicators of climate change (CC) in permafrost regions, with their relationships with climate and vegetation being crucial for the understanding of future climate change scenarios, as well as of CC feedbacks on the carbon cycle and water balance.
Antarctic ice free-areas host simplified ecosystems with vegetation dominated by mosses and lichens, and an almost negligible anthropogenic impact, providing a good template of ecosystem responses to CC. At three different Antarctic Conservation Biogeographical Regions (ACBR) sites in Antarctica located between 74° and 60°S, we compared barren ground and moss vegetated sites to understand and quantify the effects of climate (air temperature and incoming radiation) and of vegetation on GST and ALT. Our data show that incoming radiation is the most important driver of summer GST at the southernmost site, while in the other sites air temperature is the main driver of GST. Our data indicate that there is a decoupling between ALT and summer GST, because the highest GST values correspond with the thinnest ALT. Moreover, our data confirm the importance of the buffering effect of moss vegetation on GST in Antarctica. The intensity of the effect of moss cover on GST and ALT mainly depends on the species-specific moss water retention capacity and on their structure. These results highlight that the correct assessment of the moss type and of its water retention can be of great importance in the accurate modelling of ALT variation and its feedback on CC.
Thermal regime and thickness of the active layer respond rapidly to climate variations, and thus they are important measures of cryosphere changes in polar environments. We monitored air temperature ...and ground temperature at a depth of 5 cm and modeled active‐layer thickness using the Stefan and Kudryavtsev models at the Abernethy Flats site, James Ross Island, Eastern Antarctic Peninsula, in the period March 2006 to February 2016. The decadal average of air and ground temperature was −7.3 and −6.1°C, respectively, and the average modeled active‐layer thickness reached 60 cm. Mean annual air temperature increased by 0.10°C y−1 over the study period, while mean annual ground temperature showed the opposite tendency of −0.05°C y−1. The cooling took place mainly in summer and caused thawing season shortening and active‐layer thinning of 1.6 cm y−1. However, these trends need to be taken carefully because all were non‐significant at p < 0.05. The Stefan and Kudryavtsev models reproduced the active‐layer thickness with mean absolute errors of 2.6 cm (5.0%) and 3.4 cm (5.9%), respectively, which is better than in most previous studies, making them promising tools for active‐layer modeling over Antarctica.
Climate change and its impacts on sensitive polar ecosystems are relatively little studied in Antarctic regions. Permafrost and active layer changes over time in periglacial regions of the world are ...important indicators of climate variability. These changes (e. g. permafrost degradation, increasing of the active layer thickness) can have a significant impact on Antarctic terrestrial ecosystems. The study site (AWS-JGM) is located on the Ulu Peninsula in the north of James Ross Island. Ground temperatures at depths of 5, 50, and 75 cm have been measured at the site since 2011, while air temperature began to be measured in 2004. The main objective is to evaluate the year-to-year variability of the reconstructed temperature of the top of the permafrost table and the active layer thickness (ALT) since 2004 based on air temperature data using TTOP and Stefan models, respectively. The models were verified against direct observations from a reference period 2011/12–2020/21 showing a strong correlation of 0.95 (RMSE = 0.52) and 0.84 (RMSE = 3.54) for TTOP and Stefan models, respectively. The reconstructed average temperature of the permafrost table for the period 2004/05–2020/21 was −5.8 °C with a trend of −0.1 °C/decade, while the average air temperature reached −6.6 °C with a trend of 0.6 °C/decade. Air temperatures did not have an increasing trend throughout the period, but in the first part of the period (2004/05–2010/11) showed a decreasing tendency (−1.3 °C/decade). In the period 2011/12–2020/21, it was a warming of 1.9 °C/decade. The average modelled ALT for the period 2004/05–2020/21 reached a value of 60cm with a trend of −1.6 cm/decade. Both models were found to provide reliable results, and thus they significantly expand the information about the permafrost and ALT, which is necessary for a better understanding of their spatiotemporal variability and the impact of climate change on the cryosphere.
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•Permafrost and active layer changes are important indicators of climate variability.•Regular study of the properties and changes of permafrost and the active layer is crucial for revealing long-term trends.•TTOP and Stefan model has advantages in obtaining data of the frozen ground.
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•Summer snow affected on active layer thermal regime and thickness significantly.•Active layer was thinner up to 20 % at parts of CALM-S covered with snow for >6 days.•Mean January ...ground temperature at 5 cm was reduced by 1.1 °C due to snow presence.
This study aims to assess the role of ephemeral snow cover on ground thermal regime and active layer thickness in two ground temperature measurement profiles on the Circumpolar Active Layer Monitoring Network – South (CALM-S) JGM site on James Ross Island, eastern Antarctic Peninsula during the high austral summer 2018. The snowstorm of 13–14 January created a snowpack of recorded depth of up to 38 cm. The snowpack remained on the study site for 12 days in total and covered 46% of its area six days after the snowfall. It directly affected ground thermal regime as indicates temperature record at snow-covered profile AWS-JGM which subsurface section was nearly 5 °C colder compared to the snow-free AWS-CALM profile. The thermal insulation effect of snow cover is also reflected in the mean monthly (January) and summer (DJF) ground temperatures on AWS-JGM that decreased by ca 1.1 and 0.7 °C, respectively. Summer thawing degree days at a depth of 5 cm decreased by ca 10% and active layer was ca 5–10 cm thinner when compared to previous snow-free summer seasons. Surveying by ground penetrating radar revealed a general active layer thinning of up to 20% in those parts of the CALM-S which were covered by snow of >20 cm depth for at least six days.
Lacustrine sediments of the Big Lachman Lake (James Ross Island, Antarctica) are dominated by clay- and silt-sized particles of varied petrographic composition. These are of volcanic origin and are ...derived predominantly from the Mendel Formation. The intensity of chemical weathering of volcanic rock particles in the sediments was expressed by the Chemical Index of Alteration (CIA), which reflects alteration of feldspars and formation of clay minerals. The observed mineral assemblage of montmorillonite, illite, and kaolinite probably originated from alteration of volcanic glass and from alteration of feldspars to clay minerals. CIA weathering rates from the lacustrine sediments are similar to those of Early Jurrasic high-Ti volcanic rocks of the Mount Poster Formation and Middle Jurrasic high-Ti volcanic rocks of the Mapple Formation from the Antarctic Peninsula. However, the sediments show a good fit in OIB-normalized incompatible trace-element patterns only with the high-Ti volcanic rocks from the Middle Jurassic rhyolites of the Mapple Formation, while the fit with Cenozoic basalts of the James Ross Island Volcanic Group is poorer. Rocks from the Antarctic Peninsula were probably transported through the Prince Gustav channel by small glaciers during the Neogene and Quaternary.
Diatoms constitute an important and diverse component of terrestrial protist communities but remain poorly studied, especially in the Antarctic realm. Here, we investigated the diversity and ...community structure of the terrestrial diatom flora from the Ulu Peninsula, James Ross Island (Maritime Antarctic Region) using a morphology-based dataset and physico-chemical measurements. A total of 97 taxa belonging to 27 genera was identified in 59 samples from terrestrial environments, including soils and rock walls. The flora was dominated by the genera
Hantzschia
,
Luticola
, and
Humidophila
. Eight distinct diatom assemblages could be distinguished and were mainly structured by differences in environmental characteristics such as vegetation coverage, moisture, conductivity, pH, and nutrient concentrations. In general, James Ross Island harboured a unique diatom flora as evidenced by very low similarity values with other (sub-)Antarctic localities. Only 16% of the taxa have a typical cosmopolitan distribution, whereas 70% showed a restricted Antarctic distribution, supporting previous indications of high species-level endemism in environments characterized by harsh abiotic conditions. In addition, several of the cosmopolitan species uncovered in this study might harbour substantial levels of hidden diversity, including endemic taxa, as previously revealed for the
Pinnularia borealis
species complex on James Ross Island. Taken together, the present study improves our knowledge and understanding of the diversity, ecology, and community structure of the terrestrial diatom flora of Ulu Peninsula and highlights that soils and wet rock walls represent important terrestrial habitats in this transitional zone between Maritime and Continental Antarctica.
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