Climatic change on King George Island in the years 1948–2011

Walsh J.E., Chapman W.L.

Abstract Monthly surface air temperatures from land surface stations, automatic weather stations, and ship/buoy observations from the high-latitude Southern Hemisphere are synthesized into gridded analyses at a resolution appropriate for applications ranging from spatial trend analyses to climate change impact assessments. Correlation length scales are used to enhance information content while limiting the spatial extent of influence of the sparse data in the Antarctic region. The correlation length scales are generally largest in summer and over the Antarctic continent, while they are shortest over the winter sea ice. Gridded analyses of temperature anomalies, limited to regions within a correlation length scale of at least one observation, are constructed and validated against observed temperature anomalies in single-station-out experiments. Trends calculated for the 1958–2002 period suggest modest warming over much of the 60°–90°S domain. All seasons show warming, with winter trends being the largest at +0.172°C decade−1 while summer warming rates are only +0.045°C decade−1. The 45-yr temperature trend for the annual means is +0.082°C decade−1 corresponding to a +0.371°C temperature change over the 1958–2002 period of record. Trends computed using these analyses show considerable sensitivity to start and end dates, with trends calculated using start dates prior to 1965 showing overall warming, while those using start dates from 1966 to 1982 show net cooling over the region. Because of the large interannual variability of temperatures over the continental Antarctic, most of the continental trends are not statistically significant. However, the statistically significant warming over the Antarctic Peninsula is the strongest and most seasonally robust in the spatial patterns of temperature change. Composite (11-model) global climate model (GCM) simulations for 1958–2002 with forcing from historic aerosol and greenhouse gas concentrations show warming patterns and magnitudes similar to the corresponding observed trends for the 45-yr period. GCM projections for the rest of the twenty-first century, however, discontinue the pattern of strongest warming over the Antarctic Peninsula, but instead show the strongest warming over the Antarctic continent.

Vaughan D.G., Marshall G.J., Connolley W.M., Parkinson C., Mulvaney R., Hodgson D.A., King J.C., Pudsey C.J., Turner J.

The Intergovernmental Panel on Climate Change (IPCC) confirmed that mean global warming was 0.6 ± 0.2 °C during the 20th century and cited anthropogenic increases in greenhouse gases as the likely cause of temperature rise in the last 50 years. But this mean value conceals the substantial complexity of observed climate change, which is seasonally- and diurnally-biased, decadally-variable and geographically patchy. In particular, over the last 50 years three high-latitude areas have undergone recent rapid regional (RRR) warming, which was substantially more rapid than the global mean. However, each RRR warming occupies a different climatic regime and may have an entirely different underlying cause. We discuss the significance of RRR warming in one area, the Antarctic Peninsula. Here warming was much more rapid than in the rest of Antarctica where it was not significantly different to the global mean. We highlight climate proxies that appear to show that RRR warming on the Antarctic Peninsula is unprecedented over the last two millennia, and so unlikely to be a natural mode of variability. So while the station records do not indicate a ubiquitous polar amplification of global warming, the RRR warming on the Antarctic Peninsula might be a regional amplification of such warming. This, however, remains unproven since we cannot yet be sure what mechanism leads to such an amplification. We discuss several possible candidate mechanisms: changing oceanographic or changing atmospheric circulation, or a regional air-sea-ice feedback amplifying greenhouse warming. We can show that atmospheric warming and reduction in sea-ice duration coincide in a small area on the west of the Antarctic Peninsula, but here we cannot yet distinguish cause and effect. Thus for the present we cannot determine which process is the probable cause of RRR warming on the Antarctic Peninsula and until the mechanism initiating and sustaining the RRR warming is understood, and is convincingly reproduced in climate models, we lack a sound basis for predicting climate change in this region over the coming century.

Smith K.L., Baldwin R.J., Glatts R.C., Chereskin T.K., Ruhl H., Lagun V.

An autonomous weather station (Terrestrial station) was developed and deployed at Deception Island, Antarctica, an active volcanic island, to monitor the daily weather conditions as part of a long time-series marine ecosystem study of the sunken caldera, Port Foster. The principal components of the Terrestrial station were a time-lapse digital camera, ultrasonic wind sensor, controller, wind turbine generators, and batteries. The Terrestrial station was installed on a ridge at 200 m altitude overlooking Port Foster and the surrounding terrain from 9 March 1999 until 20 November 2000. Ice cover on Port Foster began in late July 2000 and was intermittently visible through early November. Daily averaged wind speeds ranged from 0.2 m s−1 in October to 47.4 m s−1 in June, with the prevailing direction from the southwest and less frequently from the northeast. Daily averaged air temperatures fluctuated from a low of −12.6°C in August 2000 to 2.7°C in March 1999. Weather conditions measured at Deception Island were generally consistent with those concurrently measured in the region of the South Shetland Islands. Ice cover in Port Foster was less pronounced in 1999 and 2000 than reported in previous years, suggesting regional warming.

King J.C., Comiso J.C.

Over 50 years of observations from climate stations on the west coast of the Antarctic Peninsula show that this is a region of extreme interannual variability in near-surface temperatures. The region has also experienced more rapid warming than any other part of the Southern Hemisphere. In this paper we use a new dataset of satellite-derived surface temperatures to define the extent of the region of extreme variability more clearly than was possible using the sparse station data. The region in which satellite surface temperatures correlate strongly with west Peninsula station temperatures is found to be quite small and is largely confined to the seas just west of the Peninsula, with a northward and eastward extension into the Scotia Sea and a southward extension onto the western slopes of Palmer Land. Correlation of Peninsula surface temperatures with surface temperatures over the rest of continental Antarctica is poor confirming that the west Peninsula is in a different climate regime. The analysis has been used to identify sites where ice core proxy records might be representative of variations on the west coast of the Peninsula. Of the five existing core sites examined, only one is likely to provide a representative record for the west coast.

Comiso J.C.

The surface air temperatures observed from stations in Antarctica have been shown to have predominantly positive trends that are as high as 0.5°C decade−1 along the Antarctic Peninsula. To evaluate whether the trends are caused by a local or large-scale phenomenon in the Antarctic region, surface temperatures inferred from infrared satellite data from 1979 to 1998 have been analyzed in combination with data from 21 stations that have long record lengths. The surface temperatures derived from infrared data are coherent spatially and temporally and are shown to agree well with Antarctic station data with a correlation coefficient of 0.98 and a standard deviation of about 3°C. The trend analysis on station data yielded on the average 0.012 ± 0.008°C yr−1 and −0.008 ± 0.025°C yr−1 for the 45- and 20-yr record, respectively. The latter reasonably agrees with the trend of −0.042 ± 0.067°C yr−1 inferred from the satellite 20-yr record. The 20-yr record length is shown to be about the minimum length requ...

Braun M., Saurer H., Vogt S., Simões J.C., Goßmann H.

During the austral summer 1997–1998 three automatic weather stations were operated at different altitudes on the sub-Antarctic ice cap of King George Island (South Shetland Islands). Snowmelt was derived from energy balance computations. Turbulent heat fluxes were calculated from meteorological measurements using the bulk aerodynamic approach, with net radiation being measured directly. Modelled ablation rates were compared with readings at ablation stakes and continuously measured snow height at a reference site. Snow depletion and daily snowmelt cycles could be well reproduced by the model. Generally, radiation balance provided the major energy input for snowmelt at all altitudes, whereas sensible heat flux was a second heat source only in lower elevations. The average latent heat flux was negligible over the entire measuring period. A strong altitudinal gradient of available energy for snowmelt was observed. Sensible heat flux as well as latent heat flux decreased with altitude. The measurements showed a strong dependence of surface energy fluxes and ablation rates on large-scale atmospheric conditions. Synoptic weather situations were analysed based on AVH RR infrared quicklook composite images and surface pressure charts. Maximum melt rates of up to 20 mm per day were recorded during a northwesterly advection event with meridional air mass transport. During this northwesterly advection, the contribution of turbulent heat fluxes to the energy available for snowmelt exceeded that of the radiation balance. For easterly and southerly flows, continentally toned, cold dry air masses dominated surface energy balance terms and did not significantly contribute to ablation. The link between synoptic situations and ablation is especially valuable, as observed climatic changes along the Antarctic Peninsula are attributed to changes in the atmospheric circulation. Therefore, the combination of energy balance calculations and the analysis of synoptic-scale weather patterns could improve the prediction of ablation rates for climate change scenarios. Copyright © 2001 Royal Meteorological Society

Van Den Broeke M.

The climate of Faraday, situated at the west coast of the Antarctic Peninsula (AP), is strongly influenced by the extent of sea ice cover in the Amundsen and Bellingshausen Seas (ABS). ABS sea ice cover is negatively correlated with Faraday annual mean temperature, wind speed and cloudiness, while a positive correlation was found with precipitation frequency. The amplitude of the semi-annual oscillation (SAO) and wintertime ABS sea ice extent are coupled as follows: in years with a poorly-developed SAO, the northwestward migration of the circumpolar pressure trough from April to July is suppressed, causing negative sea ice anomalies in the ABS that persist throughout the winter. The weakening of the SAO since the late 1970s has led to: an increase of annual mean wind speed and cloudiness in the region, one of the possible causes for the onset of the long-term ABS sea ice cover decrease; and changes in the annual cycles of wind speed and cloudiness such that sea ice growth in the period April-July has decreased, causing negative winter sea ice anomalies in the ABS and enhanced regional warming.

Marshall G.J., King J.C.

The Southern Hemisphere reveals markedly different circulation patterns associated with extreme warm and cold Antarctic Peninsula (AP) winter temperatures. Warm winters are associated with negative 500 hPa height anomalies in the Amundsen Sea-Bellingshausen Sea (AS-BS) and positive anomalies in the South Pacific (SP) and Scotia Sea with opposing anomalies existent in cold winters. Furthermore, a switch in the relative strength of the two arms of the New Zealand split jet, the subtropical jet (STJ) and polar front jet (PFJ), occurs with the PFJ (STJ) strengthened and the STJ (PFJ) weakened in warm (cold) years leading to increased cyclonic activity in the AS-BS (SP) and a corresponding decrease in the SP (AS-BS). These hemispheric anomaly patterns bear a strong resemblance to those associated with El Nino-Southern Oscillation (ENSO) events, and their origins can be ascribed to tropical sea surface temperatures (SST) changes. However, the correspondence between warm (cold) ENSO events and cold (warm) winters is not perfect. Potential contributors to this non-linearity include intraseasonal tropical SST variations (not necessarily represented in the usual filtered ENSO indices) and the persistence of local sea ice anomalies west of the Peninsula.

King J.C., Harangozo S.A.

Temperature records from slations on the west roast of the Antarctic Peninsula show a very high level of interannual variability and, over the last 50 years, larger warming trends than are seen elsewhere in Antarctica. in this paper we investigate the role of atmospheric circulation variability and sea-ice extent variations in driving these changes. Owing to a lack of independent data, the reliability of Antarctic atmospheric analyses produced in the 1950s and 1960s cannot be readily established, but examination of the available data suggests that there has been an increase in the northerly component of the circulation over the Peninsula since the late 1950s. Few observations of sea-ice extent are available prior to 1973, but the limited data available indicate that the ice edge to the west of the Peninsula lay to the north of recently observed extremes during the very cold conditions prevailing in the late 1950s. The ultimate cause of the atmospheric-circulation changes remains to be determined and may lie outside the Antarctic region.

Turner J., Colwell S.R., Harangozo S.

Observations of precipitation events at Faraday and Rothera Stations are analyzed to investigate the spatial and temporal variability of precipitation along the western coastal (Pacific) side of the Antarctic Peninsula. The record of observations made at Faraday since 1956 show a statistically significant increase in the number of winter-season precipitation events. During this season, there are now, on the average, almost 50% more reports of precipitation than during the 1950s. On a year-to-year basis the number of precipitation events is not correlated with the mean surface temperature on the western side of the Antarctic Peninsula but is dependent on synoptic weather system activity. The annual total number of precipitation events at Rothera is also increasing, but because the length of the record is relatively short, this is not statistically significant. The semiannual cycle in the latitudinal location and depth and position of the circumpolar trough is reproduced in the record of precipitation events at both Faraday and Rothera. It is argued that the systematic increase in the number of precipitation events at Faraday since the 1950s is associated with changes in the depression tracks across the Bellingshausen Sea, with an increase in the number of depressions approaching from outside the Antarctic rather than from the west.

Jacka T.H.

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.

Leal Leal M.A., Tovar Rodríguez D., de Pablo Hernandez M.Á., Bonilla Gómez M.A., Leone G., Tchegliakova Nikolaevna N., Sánchez Nieves J., Molina Jurado A., San Martín Lobos J.T.

Abstract The establishment of the possible presence of life on Mars (past or present) is based on the study of planetary analogues, which allow in situ analysis of the environments in which living organisms adapt to often extreme conditions. Although Mars has been a candidate for hosting life, based on observations made decades ago, it is thanks to the characteristics identified in environments, mainly volcanic, that it has been possible to calibrate instruments and detail the features of the red planet. In this paper, we present a review of the main characteristics of different planetary analogues, particularly deepening the study of Antarctica, to later expose the factors studied in Deception Island that have contributed to considering it as an analogue of Mars from different perspectives. Although geological and geomorphological studies on the analogies of the island already exist, detailed analyses that present the approach of astrobiological analogues are required, thus allowing further research.

Plenzler J., Budzik T., Wójcik‐Długoborska K.A., Bialik R.J.

ABSTRACTThe dataset presented in the paper contains meteorological data from four automatic weather stations (AWS) located in the central and western parts of King George Island (near Arctowski Station and Cape Lions Rump). The dataset includes daily mean, maximum and minimum values of air temperature, relative air humidity, air pressure, wind speed and daily sum of solar radiation. The measurement period ran from 2018.01.01 to 2023.12.31, but it is shorter for two of the stations. Mean values were calculated from measurements taken every 10 min. Direct measurements were used to identify extreme values. The described dataset consists offour files, each for one AWS. It is available in the PANGEA online repository under a non‐restrictive CC BY 4.0 licence for anyone after registration. Despite a strong correlation between the daily mean values of the parameters measured at certain stations, some differences between them were also noticeable. These were due to their location at different altitudes, in a place open to the sea or in a shaded place. Generally, values of wind speed, air humidity, solar radiation and pressure are similar to Arctowski during 2013–2017. The only notable distinction is that the mean annual air temperature and the mean air temperature in the winter months were higher than during 1977–1999 and 2013–2017. The data presented can be used as background for other research projects on King George Island, as well as for analysis of the meteorological conditions themselves. They may also be useful for the evaluation of the management plans of the eight Antarctic Specially Protected Areas or Antarctic Specially Managed Area no. 1 that are located on King George Island.

Newsham K.K.

The surface temperatures of Antarctic soils and bryophyte colonies can fluctuate from close to freezing point to approximately 20 °C under clear skies around solar noon during midsummer. However, whether diurnally fluctuating temperatures influence the growth and metabolic activities of fungi inhabiting these substrates remains unknown. Here, 10 isolates of Pseudogymnoascus roseus, an ascomycete that is widespread in Antarctica, were exposed in vitro to temperatures fluctuating daily from 2 °C to 15–24 °C. Relative to controls incubated at the constant mean temperature of each treatment, temperatures fluctuating from 2 °C to ≥18 °C inhibited the growth of all isolates by 10–51 % at 24 h and 48 h, and by up to 79 % for individual isolates. Over a period of 21 days, all fluctuating temperature treatments reduced mean growth rates by between 3 % and 48 %, but had few effects on specific β-glucosidase activity, a proxy measure for metabolic activity. It is concluded that temperatures fluctuating diurnally to ≥18 °C during summer in mesic Antarctic soils and bryophyte colonies, exacerbated by the occurrence of climate-change associated heatwaves, are likely to inhibit the growth of P. roseus and perhaps also other ecologically important fungi.

Cichecka A., Saniewska D., Balazy P., Saniewski M.

The Antarctic plays a critical role in global mercury cycling as both a sink of Hg and, in response to rapid global warming, an emerging source of Hg through its release from thawing permafrost and recessing glaciers. At the present time, Antarctica and surrounding areas have little mercury contamination in comparison to other regions of the world. Understanding the sources and transformations of Hg in the Antarctic will be particularly important in predicting the role of a changing environment in the mercury cycle as emissions and global climate change. Study samples were collected at 12 stations, categorized into three groups based on the human or animal presence and flora. Sampling took place in December 2018 and January 2019, and soil and parent rock samples were collected and analyzed for total mercury concentration and its fractions using atomic absorption spectroscopy. Bedrock samples collected on the coast of Admiralty Bay were found to have low organic matter content, while soil samples from the west shore of the bay had a high variability of organic matter content, ranging from 3 % to 41 %. The concentration of total mercury in bedrock ranged from 2.1 ng/g to 15.0 ng/g, and in soil samples, the total mercury concentration ranged from 4.7 ng/g to 143.1 ng/g. This paper reviews current knowledge of Hg cycling in the Antarctic, including its sources, fate, and effects on the ecosystem. The implications of climate change for Hg cycling in the region are also discussed, highlighting the need for continued research to better understand the potential impacts of Hg contamination in the Antarctic.

ROSA K.K., PERONDI C., LORENZ J.L., AUGER J.D., CAZAROTO P., PETSCH C., SIQUEIRA R.G., SIMÕES J.C., VIEIRA R.

SUAREZ W., BELLO C., CRUZ R., ZEGARRA J., ARIAS S., BRONDI F.

MIRANDA C.O., SCHAEFER C.E., SOUZA J.J., GUIMARÃES L.M., MAIA P.V., SUL J.A.

LORENZ J.L., ROSA K.K., PETSCH C., PERONDI C., IDALINO F.D., AUGER J.D., VIEIRA R., SIMÕES J.C.

Mavlyudov B.R.

Received June 9, 2023; revised September15, 2023; accepted October 2, 2023We present an analysis of the equilibrium line altitude (ELA) on the Bellingshausen Ice Dome on King George Island (Waterloo), Antarctica, derived only from ground-based glaciological surveys for the period 2007–2012 and 2014–2023. A good relationship was found between ELA and mean summer air temperature (XII-II months) with a coefficient of determination of about 0.8. Assuming the stability of this relation in the past, the changes in the ELA during the entire period of observations at Bellingshausen weather station (from 1968) were reconstructed. Since negative ELA values were obtained for some years, which is physically impossible, they were artificially adjusted to sea level. A good correlation of air temperature between the Bellingshausen and Deception Island weather stations allowed extending the reconstruction of ELA for a longer period (from 1947).By cleaning up the strong interannual fluctuations in ELA using five-year moving averages, two complete periods of ELA change (from minimum to minimum) were identified for approximately 20 years (1947–1968) and 45 years (1968–2013). From 2014 to present time, the third period has been continuing. At the apogee of each period, the ELA was higher than the Bellingshausen Ice Dome height, which indicates that in these years the ice dome completely lost accumulation area. For the Bellingshausen and Warsaw ice domes, a pattern of higher ELA position on the western and southern slopes compared to the eastern slopes was revealed, which is probably applicable to the entire King George Island.Since the ELA variations on King George Island are generally synchronous with its variations on Livingston Island, the reconstructed ELA on the Bellingshausen Ice Dome can probably be useful for reconstructing the glaciation history of the South Shetland Islands.

Kundu B., Chatterjee D., Xie F., Singh D.

Climate variability is thought to have an impact on the Ronne Ice Shelf (RIS), one of the largest ice shelf in Antarctica, located at the mouth of the Weddell Sea. However, investigations evaluating the impact of climate variability on the geometry (front edge) of this ice body have not yet been done. This study examines a spatial-temporal shift in the front edge of the Ronne Ice Shelf during the years 2004–2019 using an integrated approach based on remote sensing and climate data. The Moderate Resolution Imaging Spectro-radiometer (MODIS) satellite images have been used to study the changes in the ice shelf along transects drawn at a constant interval of 5 km throughout the 16-year period over the second half of the austral summer months (February to March). The study reveals that there has been net progradation of ∼20 km in the front edge of the ice shelf in the sector 2 between 2004 and 2019. This progradation in the ice shelf may be attributed to draining of upper ice streams to the RIS and the decrease in temperature. Thus, the present study establishes how a combination of the use of satellite imagery and statistics can effectively be used to comprehend and quantify changes in the variability of the front edge of the ice shelf.

Zmarz A., Karlsen S.R., Kycko M., Korczak-Abshire M., Gołębiowska I., Karsznia I., Chwedorzewska K.

Polar areas are among the regions where climate change occurs faster than on most of the other areas on Earth. To study the effects of climate change on vegetation, there is a need for knowledge on its current status and properties. Both classic field observation methods and remote sensing methods based on manned aircraft or satellite image analysis have limitations. These include high logistic operation costs, limited research areas, high safety risks, direct human impact, and insufficient resolution of satellite images. Fixed-wing unmanned aerial vehicle beyond the visual line of sight (UAV BVLOS) missions can bridge the scale gap between field-based observations and full-scale airborne or satellite surveys. In this study the two operations of the UAV BVLOS, at an altitude of 350 m ASL, have been successfully performed in Antarctic conditions. Maps of the vegetation of the western shore of Admiralty Bay (King George Island, South Shetlands, Western Antarctic) that included the Antarctic Specially Protected Area No. 128 (ASPA 128) were designed. The vegetation in the 7.5 km2 area was mapped in ultra-high resolution (<5 cm and DEM of 0.25 m GSD), and from the Normalized Difference Vegetation Index (NDVI), four broad vegetation units were extracted: “dense moss carpets” (covering 0.14 km2, 0.8% of ASPA 128), “Sanionia uncinata moss bed” (0.31 km2, 1.7% of ASPA 128), “Deschampsia antarctica grass meadow” (0.24 km2, 1.3% of ASPA 128), and “Deschampsia antarctica–Usnea antarctica heath” (1.66 km2, 9.4% of ASPA 128). Our results demonstrate that the presented UAV BVLOS–based surveys are time-effective (single flight lasting 2.5 h on a distance of 300 km) and cost-effective when compared to classical field-based observations and are less invasive for the ecosystem. Moreover, unmanned airborne vehicles significantly improve security, which is of particular interest in polar region research. Therefore, their development is highly recommended for monitoring areas in remote and fragile environments.

Heredia Barión P., Roberts S.J., Spiegel C., Binnie S.A., Wacker L., Davies J., Gabriel I., Jones V.J., Blockley S., Pearson E.J., Foster L., Davies S.J., Roland T.P., Hocking E.P., Bentley M.J., et. al.

To provide insights into glacier-climate dynamics of the South Shetland Islands (SSI), NW Antarctic Peninsula, we present a new deglaciation and readvance model for the Bellingshausen Ice Cap (BIC) on Fildes Peninsula and for King George Island/Isla 25 de Mayo (KGI) ~62°S. Deglaciation on KGI began after c. 15 cal. ka BP and had progressed to within present-day limits on the Fildes Peninsula, its largest ice-free peninsula, by c. 6.6–5.3 cal. ka BP. Probability density phase analysis of chronological data constraining Holocene glacier advances on KGI revealed up to eight 95% probability ‘gaps’ during which readvances could have occurred. These are grouped into four stages – Stage 1: a readvance and marine transgression, well-constrained by field data, between c. 7.4 and 6.6 cal. ka BP; Stage 2: four probability ‘gaps’, less well-constrained by field data, between c. 5.3 and 2.2 cal. ka BP; Stage 3: a well-constrained but restricted ‘readvance’ between c. 1.7 and 1.5 cal. ka BP; Stage 4: two further minor ‘readvances’, one less well-constrained by field data between c. 1.3 and 0.7 cal. ka BP (68% probability), and a ‘final’ well-constrained ‘readvance’ after <0.7 cal. ka BP. The Stage 1 readvance occurred as colder and more negative Southern Annular Mode (SAM)-like conditions developed, and marginally stronger/poleward shifted westerly winds led to more storms and precipitation on the SSI. Readvances after c. 5.3 cal. ka BP were possibly more frequent, driven by reducing spring/summer insolation at 62°S and negative SAM-like conditions, but weaker (equatorward shifted) Westerlies over the SSI led to reduced storminess, restricting readvances within or close to present day limits. Late Holocene readvances were anti-phased with subaquatic freshwater moss layers in lake records unaffected by glaciofluvial inputs. Retreat from ‘Neoglacial’ glacier limits and the recolonisation of lakes by subaquatic freshwater moss after 1950 CE is associated with recent warming/more positive SAM-like conditions.

Heredia Barión P.A., Strelin J.A., Roberts S.J., Spiegel C., Wacker L., Niedermann S., Bentley M.J., Pearson E.J., Czalbowski N.T., Davies S.J., Schnetger B., Grosjean M., Arcusa S., Perren B., Hocking E.P., et. al.

The timing and impact of deglaciation and Holocene readvances on the terrestrial continental margins of the Antarctic Peninsula (AP) have been well-studied but are still debated. Potter Peninsula on King George Island (KGI) (Isla 25 de Mayo), South Shetland Islands (SSI), NW Antarctic Peninsula, has a detailed assemblage of glacial landforms and stratigraphic exposures for constraining deglacial landscape development and glacier readvances. We undertook new morphostratigraphic mapping of the deglaciated foreland of the Warszawa Icefield, an outlet of the Bellingshausen (Collins) Ice Cap on Potter Peninsula, using satellite imagery and new lithofacies recognition and interpretations, combined with new chronostratigraphic analysis of stratigraphic sections, lake sediments, and moraine deposits. Results show that the deglaciation on Potter Peninsula began before c. 8.2 ka. Around c. 7.0 ka, the Warszawa Icefield and the marine-facing Fourcade Glacier readvanced across Potter Peninsula and to the outer part of Potter Cove. Evidence of further readvances on Potter Peninsula was absent until the Warszawa Icefield margin was landward of its present position on three occasions: c. 1.7–1.4 ka, after c. 0.7 ka (most likely c. 0.5–0.1 ka), and by 1956 CE. The timing of Holocene deglaciation and glacier fluctuations on Potter Peninsula are broadly coeval with other glacier- and ice-free areas on the SSI and the northern AP and likely driven by interactions between millennial–centennial-scale changes in solar insolation and irradiance, the southern westerlies, and the Southern Annular Mode.

Chelchowski M., Balazy P., Kuklinski P.

To understand the impact of anthropogenically induced transformations of biological communities, their naturally occurring fluctuation must be recognized first. Therefore, the aim of this study was to investigate the variability in Antarctic intertidal benthic assemblage faunal composition during an annual cycle (King George Island 62° S). Once a month, from December 2016 to November 2017, samples were collected at low-, mid- and high-tidal levels. Polychaetes were the most speciose group (15 species), followed by amphipods (12). Throughout the year, the most numerous taxa were gastropods (38% of the total number), followed by amphipods (23%) and bivalves (22%). The general pattern of the number of species and their abundance and biomass depended on the season and exhibited the highest values in austral autumn (April–June). Both species richness and abundance were highest in June and lowest in August. This study discovered that Antarctic intertidal macrofauna assemblages quickly respond to changes in environmental conditions and thus reflect seasonal climate fluctuations. The rapid development of these assemblages when the conditions are favourable proves their opportunistic and highly adaptable nature, which is potentially a good prognosis for survival in this ever-changing ecosystem. • Intertidal macrofauna is dominated by gastropods, followed by amphipods and bivalves. • Intertidal assemblages decrease in abundance from lower to higher tidal levels. • In autumn, the intertidal macrofauna was the most diverse and abundant. • Antarctic intertidal fauna quickly respond to natural environmental fluctuations. • The dominant species year around are also most abundant at higher tidal levels.

Wawrzynek-Borejko J., Panasiuk A., Hinke J.T., Korczak-Abshire M.

In recent years, functional changes in Southern Ocean are becoming more noticeable, due to climate change and increasing human impacts, including a growing fishery that is concentrating in the Antarctic Peninsula (AP) region. Antarctic krill Euphausia superba is often the primary prey species for animals such as Pygoscelis penguins, a sentinel species for ecosystem monitoring and management. During the last two decades in the AP gentoo penguin numbers (Pygoscelis papua) have increased and their range has shifted southward, in contrast to the decline in numbers of Adélie (P. adeliae) and chinstrap (P. antarcticus) penguins. Given divergent population trends, the goal of this study was to examine differences in their diet, and size structure of Antarctic krill recovered from penguin diet samples. The study is based on diet samples collected during the austral summers on King George Island (South Shetland Islands) where P. adeliae, P. antarcticus, and P. papua breed in mixed colonies. Results indicate that the penguins consumed krill of similar sizes during the breeding period. In contrast to prior diet studies, we found higher proportions of krill in the gentoo diet and changes in the percentage of krill in the diet relative obtained during 1970s. The similarity in diets among all three species suggests that the availability prey items (e. g., fishes) may be changing and driving higher dietary overlap. Moreover, we also check differences in krill length among penguin individuals and we did not find any statistically significant differences. We also found plastic debris in penguin stomachs during both summers.