«Changing Polar Regions 25th International Congress on Polar Research March 17-22, 2013, Hamburg, Germany German Society for Polar Research Edited by ...»
The Amundsen Sea sector of the largely marine-based and therefore conditionally unstable West Antarctic Ice Sheet (WAIS) contains enough ice to raise global sea level by ca. 1.5 metres. At present, ice streams draining this sector into the Southern Ocean, especially glaciers flowing into Pine Island Bay in the eastern Amundsen Sea embayment, are undergoing considerable mass loss characterised by major thinning, flow acceleration and rapid grounding-line retreat. Sub-ice shelf melting by relatively warm Circumpolar Deep Water (CDW) upwelling onto the continental shelf is held responsible for these dynamical changes but atmospheric warming in West Antarctica may also have contributed to them. In contrast to the modern situation, the long-term history of the Amundsen Sea sector and the mechanisms forcing its deglaciation during the Holocene are only poorly constrained.
We will present new palaeoenvironmenal data obtained from marine sediment cores collected in Pine Island Bay. The cores targeted shallow sites on the inner continental shelf and successfully recovered sedimentary sequences bearing calcareous microfossils. Radiocarbon ages on these microfossils demonstrate that the grounding line of the WAIS retreated to within ~100 km of its modern position before ca. 10 kyr BP (thousand years before present), which is consistent with an early WAIS retreat from near-coastal locations in the western Amundsen Sea embayment. Currently, there is no evidence that the grounding line had retreated landward of its modern position during the Holocene. Therefore, the chronological constraints may imply that during the last 10 kyr any episodes of fast grounding-line retreat similar to those observed today were short-lived and rare.
"Changing Polar Regions" - 25th International Congress on Polar Research 2013 Preliminary geochemical data from benthic and planktonic foraminifera tests in the cores from Pine Island Bay reveals that intense CDW upwelling coincided with and may have forced the deglaciation of the inner continental shelf. Furthermore, we observe a significant change of the benthic foraminifera fauna during the early Holocene, which we interpret to indicate the collapse of an ice shelf covering the inner part of the bay. We speculate that this ice shelf had buttressed ice draining into the eastern Amundsen Sea embayment, and that its removal triggered rapid icesheet thinning in the hinterland.
"Changing Polar Regions" - 25th International Congress on Polar Research 2013 ICEMAR: BETTER ACCESSIBILITY TO ACTUAL SEA ICE
Funded by the EU, ICEMAR (www.icemar.eu) is a project for better delivery of actual sea ice information onto ships, but can also used in the field and on land as long as a communication channel is available. The information can be in form of ice charts, but also satellite information of ice forecasts from numerical models. A server, based somewhere in the world, collects the information from different providers, the user aboard gets a catalog of available (now and in the near future) information and can manually choose which information he wants, but can also subscribe to certain feed.
It is also possible to order only a subset (e.g. geographic area, lower spatial and temporal resolution) of a certain product. The system can also take into consideration, that the ships moves and adjust the area of interest accordingly. The on board ICEMAR manger then takes care that the information get aboard using the ships communication line, taking also into consideration, that the transfer speed can be quite low in polar regions.
The “on board” ICEMAR manger will be available on a laptop at the conference for a real time experience.
"Changing Polar Regions" - 25th International Congress on Polar Research 2013 DIE ERWÄRMUNG DER ARKTIS UND IHRE AUSWIRKUNGEN AUF
Etwa ein Viertel der kontinentalen Erdoberfläche wird von Permafrost unterlagert.
Dieser dauerhaft gefrorene Untergrund ist vor allem in den weiten Permafrostgebieten der Tundren und der borealen Waldgebiete Asiens und Nordamerikas mit Mächtigkeiten bis über 1000 m weit verbreitet. Klimaänderungen verändern das thermische Regime des Permafrosts, führen zu seiner Degradation und wirken sich vielfältig auf die Landschaft, die Infrastruktur in besiedelten Regionen und die Ökosysteme insbesondere der Arktis und Subarktis aus.
Die raschesten Reaktionen auf wechselnde Klimabedingungen werden an der Grenzschicht Permafrost – Atmosphäre ablaufen, wobei es bei einer Erwärmung vor allem zu einer Erhöhung der saisonalen Auftautiefe kommen wird. Dies hat unter anderem einen starken Einfluss auf die Stabilität des organischen Kohlenstoffs der in großen Mengen in den Böden gebunden ist und je nach Änderung des Energie- und Wasserhaushaltes der oberflächennahen Schicht, zu positiven als auch zu negativen Rückkopplungseffekten in Bezug auf das Anwachsen der Treibhausgase Kohlendioxid und Methan in der Atmosphäre führen kann.
Neben dem oberflächennahen Kohlenstoffumsatz durch die Aktivität von Mikroorganismen findet man freies Methan auch in tiefer liegenden gefrorenen Schichten des Permafrosts. Ein klimabedingtes Tauen des Permafrosts und eine Intensivierung der Erosion der eisreichen arktischen Küsten kann zu einer Freisetzung von bislang noch nicht abschätzbaren Treibhausgasmengen in die Atmosphäre führen.
In den Schelf- und Tieflandsgebieten Eurasiens und Nordamerikas treten im Permafrost selbst oder im Untergrund hohe Methankonzentrationen in Form von Gashydraten auf, deren Degradation als Folge der Klimaerwärmung zu einem derzeit nicht abschätzbaren zusätzlichen Methan-Eintrag in die Atmosphäre führen kann.
Verschiedene internationale Projekte, die in enger Verzahnung von Prozessstudien mit Langzeitreihen sowie Energie-, Wasser- und Treibhausgasflüssen am Boden und deren Verknüpfung mit Klimamodellen diese komplexe Problematik erfassen möchten, haben in der letzten Zeit begonnen. Neben dem vom AWI koordinierten FP 7 Projekt der EU „PAGE21“ sind das Japanische GRENE-TEA Projekt und das Kanadische ADAPT-Projekt zu nennen.
"Changing Polar Regions" - 25th International Congress on Polar Research 2013 NEW DATA ABOUT MATERIALS FOR NEST BUILDING BY THE
KELP GULL IN THE ARGENTINE ISLAND AREA (MARITIMEANTARCTICA)
During the last 50 years, the region including the Antarctic Peninsula and its adjacent archipelagos, also known as the Maritime Antarctic, has experienced one of the fastest rates of regional climate warming recorded on the planet. One biological consequence attributed to this climatic warming and associated changes has been a considerable increase in the population numbers and extents of the two native species of vascular plants, Deschampsia Antarctica Desv. and Colobanthus quitensis (Kunth.) Bartl. occurring in the region Birds have been suggested to be partially responsible for this spread, potentially transporting adhering seeds or other viable plant fragments. However, explicit confirmation of any mechanism by which birds may have transported such propagules into the Antarctic or between locations therein remains unavailable.
Recently, based on published reports of plant species utilization by Antarctic birds during nest construction, we have proposed three regionally resident candidate species to be capable of transferring vascular plant propagules, the kelp gull (Larus dominicanus), the south polar skua (Catharacta maccormicki), and the brown skua (Catharacta lonnbergi). As these species spend time on or near land both during the austral summer in Antarctica and in the winter after migration to South America, in principle they could act as transfer vectors for viable propagules both on local and inter-regional scales, i.e. by collecting and moving plant material in the local area while building nests, and by inadvertently carrying attached propagules (zoochory) during migratory transfer from South America into the Antarctic. Yet another species, the southern giant petrel (Macronectes giganteus) has also been reported to utilize grass as a nesting material. However, this species is very sensitive to disturbance and its nesting behaviour is difficult to study. It also does not associate with land "Changing Polar Regions" - 25th International Congress on Polar Research 2013 other than during the nesting season. The Imperial shag (Phalacrocorax atriceps King, 1828) has also been observed to incorporate components of Antarctic herb tundra vegetation within its nests.
In the present study, our goal was to assess the extent to which Larus dominicanus rely on vascular plants as a nest building material in the Argentine Islands region, and hence whether this species could be considered a major dispersal agent for components of the Antarctic herb tundra formation.
Over the 2009/2010 season, 22 samples from Larus dominicanus nests were collected and analysed in details in the vicinity of the Argentine Islands. Nearly half of the available gull nests were sampled in the Argentine Islands region. All the nests were inspected rapidly and with care in order to minimize disturbance. Additionally, we examined material lost by kelp gulls around nests.
We demonstrate that, in the Argentine Islands region, D. antarctica and some bryophytes provide most of the nest building material for the kelp gull. Other materials, including lichens, limpet shells and gull feathers, are used less frequently.
Combined evidence, thus, suggests that Larus dominicanus may be an important spread agent of the Antarctic herb tundra formation in general and Deschampsia antarctica and some bryophytes in particular. The absence of Colobanthus quitensis in the studied nests clearly reflects the rarity of this plant in the study area.
We express our gratitude to the National Antarctic Scientific Center of the State Agency for Science, Innovation, and Information of Ukraine. This study was conducted under the contract between the National Antarctic Scientific Center and the Institute of Molecular Biology and Genetics NAS of Ukraine # H/3-2011 “Development of a bioindicator system of climate change in coastal Antarctica based on the dynamics of terrestrial plant cenoses” (2011-12), as well as a joint project between the NAS of Ukraine and Polish Academy of Sciences: “Ecological and genetic basis of plants adaptation to extreme environments” (2012-14).
"Changing Polar Regions" - 25th International Congress on Polar Research 2013 BLUE ICE MORAINE GYPSUM, SØR RODANE, EAST ANTARCTICA
During the international GEA-II expedition to Sør Rondane (East Antarctica), large aggregates of gypsum crystal were found within blue-ice moraines on the south side of the mountain range (Fig. 1A). Gypsum aggregates reach one meter in diameter with individual crystal length up to 20 cm. Apparently, the gypsum grows in-situ and as a result of sublimation of the blue ice on the gravel of the moraine. Individual cobbles are incorporated into the gypsum aggregates. The gypsum does not show signs of transport. In thin section, the gypsum shows an irregular growth zoning and in part bent cleavage planes. Abundant primary fluid inclusions are present parallel to the growth zoning as well as parallel to cleavage plains (Fig. 1C). First Sr-isotope data indicate relative high values and suggest crustal affinities. This type of gypsum formation is enigmatic and has never been described before. It might indicate an important and thus far not described process, characterising a special way of interaction between the lithosphere and the cryosphere.
"Changing Polar Regions" - 25th International Congress on Polar Research 2013 NEOPROTEROZOIC/LOWER PALAEOZOIC GEODYNAMIC
EVOLUTION OF DRONNING MAUD LAND: INTEGRATING GEOLOGY
East Antarctica probably formed by amalgamation of a number of cratons along distinct Ediacaran mobile belts, including the ca. 600-500 Ma East African-Antarctic Orogen (EAAO) that dissects Dronning Maud Land (DML). New field-work during the international expeditions Geodynamic Evolution of East Antarctica (GEA) I + II in the austral summers 2010/11 and 2011/12, and first geochronological results from eastern DML reveal a complex tectonic architecture across the belt.
In western DML, the EAAO reworks older Mesoproterozoic crust of the Maud Belt;