«Changing Polar Regions 25th International Congress on Polar Research March 17-22, 2013, Hamburg, Germany German Society for Polar Research Edited by ...»
Permafrost deposits constitute a large organic carbon pool vulnerable to degradation and potential carbon release due to global warming. Permafrost sections along coastal and river bank exposures and subsea cores in northeastern Siberia were studied for organic matter characteristics and ice content. Organic matter stored in permafrost grew, accumulated, froze, partly decomposed, and refroze under different periglacial environments, reflected in specific biogeochemical and cryolithological features. For the studied individual strata (Saalian ice-rich deposits, Pre-Eemian floodplain, Eemian lake deposits, early to middle Weichselian fluvial sands, middle and late Weichselian Yedoma, Taberites, Holocene cover, Holocene thermokarst and thermoerosional sediments, submerged lagoon and fluvial deposits) organic matter accumulation, preservation, and distribution are strongly linked to a broad variety of paleoenvironmental factors and specific surface and subsurface conditions.
Permafrost deposits include twigs, leaves, peat lenses, grass roots, fine-distributed plant detritus, and particulate and dissolved organic matter. The vertical distribution of total organic carbon (TOC) in exposures varies from 0.1 wt % in fluvial deposits up to 45 wt % in Holocene peats. High TOC, high C/N, and low δ13C values reflect less decomposed organic matter accumulated under wet, anaerobic conditions characteristic of relative temperate interglacial and interstadial periods. Glacial and stadial periods are characterized by less variable, low TOC, low C/N, and high δ13C values indicating stable periglacial environments with reduced bioproductivity but stronger decomposition of organic matter under dryer, aerobic conditions.
We present an in-depth studies of organic matter distribution for the arctic permafrost zone, indicating the variability of organic matter distribution between different stratigraphical units, between the same stratigraphical unit at different study sites, and even within stratigraphic units at the same site that need to be taken into account in future inventories.
"Changing Polar Regions" - 25th International Congress on Polar Research 2013 LINKING MUNNOPSIDAE (CRUSTACEA, ISOPODA, ASELLOTA) OF
ICELANDIC WATERS TO LONG-TERM OCEANOGRAPHIC DATA
Diversity, composition and distribution of selected isopod genera of the family Munnopsidae Lilljeborg, 1864 in Icelandic waters were studied based on samples of the BIOICE (Benthic Invertebrates of Icelandic Waters) and IceAGE (Icelandic marine Animals: Genetics and Ecology) projects. Icelandic waters are important for observations on climate change, being situated at the transitions between the warmer northern North Atlantic and the colder Nordic Seas, where water exchanges are constrained by the Greenland-Scotland Ridge. Data from the NISE (Norwegian Icelandic Seas Experiment) project were used to model long-term near-bottom mean temperature and salinity values, which were afterwards connected to species data and further used for species prediction models. Of the six munnopsid genera examined in this study, 15 species were identified. In all 10,787 individuals were determined to species level. Some species were either restricted to areas north (four) or south (three) of the ridge, while most species (eight) were present on both sides.
The distributional patterns of the evaluated munnopsid genera are heavily influenced by depth. Temperature and water mass appear to play a less important role in driving the distributional pattern of Munnopsidae whereas salinity and sediment type does not appear to influence the species distribution within the study area.
"Changing Polar Regions" - 25th International Congress on Polar Research 2013 PERMAFROST-LAKE INTERACTIONS IN THE 3.6 MA OLD
EL'GYGYTGYN CRATER, NE RUSSIA
Lake El’gygytgyn provides a continuous record from the Arctic spanning the the last
3.6 Ma, and for much of this time the permafrost dynamics, lake level changes and the tectonical framework played a crucial role for sediment delivery to El’gygytgyn Crater Lake.
Our report provides an overview on how permafrost dynamics affected the lake archive based on multidisciplinary studies of cored deposits in and around the lake.
The following questions are addressed:
how did periglacial slope processes control the sediment transport, the • frequent debris flows and the mass wasting to the lake how did lake level changes affect the permafrost build-up • how thick is permafrost • how old is permafrost • We conclude that (i) tectonics presumably caused extended alluvial fan inception in the catchment. (ii) The progradational sediment transport constantly delivers material to the lake basin. (iii) The slope inclination supports sliding events. (iv) Times of higher relative lake levels during the Quaternary have induced permafrost thaw (i.e.
talik) in the lake margin and have destabilized the slopes. (v) The permafrost thickness around the lake is about 330 to 360 m. (vi) The permafrost temperature measured in a 141 m deep borehole is not in equilibrium with the modern climatic conditions, but has inherited a temperature signal from the Last Glacial Maximum.
(vii) Cryogenic weathering (freeze-thaw weathering including ice in the deposits) favors the break-up of quartz particles and the enrichment of quartz in the silt fraction on the permafrost slopes. (viii) The permafrost is about 2.5 Ma old, this is the time when the cryogenic weathering became distinctly intense.
"Changing Polar Regions" - 25th International Congress on Polar Research 2013 IMPACT OF CLIMATE CHANGE ON MARINE TRANSPORTATION ON
THE NORTHERN SEA ROUTE. PRESENT RESULTS OF THE EUPROJECT ACCESS
During the last 12 years the increase of temperatures on earth have especially affected the decrease of ice in the Arctic Ocean. According to studies of several international research institutions the ice volume (ice area x thickness) was about 76% less than 1979. These institutions predict that in summer 2020 or even earlier the entire Arctic Ocean will be free of ice.
Parallel to these developments in the Arctic a group of 27 research institutions from 11 European countries have started two years ago the EU-Project ACCESS with the aim to investigate the effect of climate change on
1. Arctic Environment •
2. Marine Transportation and Tourism •
3. Fisheries •
4. Resource Extraction and •
5. Governance, Sustainable Development and Synthesis • This presentation will concentrate on Marine Transportation on the Northern Sea Route (NSR) with presenting the scope of work and some first research activities/results on a) Air pollution measurements behind ships by DLR; b) Calculation of travelling time needed on the NSR in the past, present and in the years to come by HSVA; c) Increase of shipments along the NSR from Europe to East Asia by Nordic Bulk Carriers.
"Changing Polar Regions" - 25th International Congress on Polar Research 2013 KARUPELV VALLEY PROJECT – A LONG TERM STUDY OF
LEMMING CYCLES IN HIGH ARCTIC GREENLAND IN THE GRIP OF
Because it harbours one of the most simple vertebrate communities, the high arctic offers unparalleled opportunities to provide new insights into the mechanisms that underlie population dynamics and community processes. For now 25 years in a row, fluctuations of a lemming (Dicrostonyx groenlandicus) population have been closely monitored in the North East Greenland National Park, along with the functional and numerical responses of four predators (stoat, arctic fox, snowy owl, long tailed skua).
While it could be shown that the cyclic dynamics within this vertebrate community are primarily driven by predator-prey interactions, recent trends including a fading of these cycles suggest some main responses to climate change possibly related to significant changes in snow cover, with cascading effects on the whole vertebrate community.
This study also highlights how important long term observations are to detect such changes at the community level. Some new approaches are now included in this project to better apprehend the subtle ongoing changes affecting high-arctic environments.
"Changing Polar Regions" - 25th International Congress on Polar Research 2013 DECADAL- TO MILLENNIAL-SCALE ICE-SHEET OSCILLATIONS IN
SOUTHEASTERN WEDDELL SEA DURING THE LAST GLACIAL
Until now high-resolution sediment records from the Southern Ocean covering the Last Glacial Maximum (LGM) are very rare. Therefore there is limited knowledge about short-term regional climate fluctuations and their global correlations. To gain insight into annual to decadal-scale climate changes it is imperative to investigate varved archives. We present varved sediment records from the continental slope of the southeastern Weddell Sea. The cores originate from up to 300 m high and up to 100 km long sediment ridges, located on a terrace in 2000 – 3000 m water depth, and are accompanied by channels on their southeastern side.
During the LGM, when the grounded East Antarctic Ice Sheet margin had advanced to the shelf break, coastal polynyas formed, supported by intensified katabatic winds.
This led to increased sea-ice formation, which induced brine rejection. The produced dense, high-salinity water masses sank down the continental slope, reworked sediments and drained as contour currents into the channels. Seasonally variable current velocities led to deposition of either a muddy or silty layer, forming an annual layer couplet, a siliciclastic varve. Accordingly, the varved sediment is indicative for ice-sheet advance. Occasional interruption by bioturbated sediments, which must have been deposited during open-water conditions with inactive thermohaline convection, points to ice-sheet retreat (Weber et al., 2011).
We used the BMPix and PEAK tools (Weber et al., 2010a) to distinguish and count the siliciclastic varves. Varve thickness varies quite strongly in time and between different core sites, with a mean thickness of 0.3 – 0.75 cm, hence a mean sedimentation rate of 3 – 7.5 m/kyr. Correlations of the sites using AMS 14C ages and varve counts show that the facies changes from bioturbated to laminated sediment occurred around the same time, i.e., 23 ka, 21.5 ka, 20 ka, and 19 ka.
Although the sites only describe about five millennia during the LGM, the pacing of 1000 – 1500 years may correspond to the 1470-yr cycle (Bond et al., 1997) known from the Northern Hemisphere.
For further information on varve thickness variation we conducted bulk and evolutionary spectral analysis on laminated sections using the REDFIT (Schulz and Mudelsee, 2002) and ESALAB (Weber et al., 20b) programs. All varved sediment sections show similar decadal-scale cyclic thickness variations, with a dominant 50 – "Changing Polar Regions" - 25th International Congress on Polar Research 2013 yr cyclicity. Evolutionary spectral analysis shows, that the 50 – 85-yr cycle appears to have been a rather robust feature during the LGM. This frequency band could either relate to the Gleissberg cycle (Gleissberg, 1944) with an 87-yr cyclicity, and thus be of solar origin, or to the Atlantic Multidecadal Oscillation, a 55-80-yr cyclic North Atlantic sea surface temperature fluctuation, and thus relate to internal atmosphere-ocean interaction.
"Changing Polar Regions" - 25th International Congress on Polar Research 2013 AKKUMULATIONSVERTEILUNG IN NORDGRÖNLAND ABGELEITET AUS HOCHAUFLÖSENDEN FLUGZEUGGESTÜTZTEN EMR-MESSUNGEN.
Die regionale Verteilung der Akkumulation auf Eisschilden ist ein wichtiger Parameter in der Bestimmung der Massenbilanz sowie in der Modellierung. Zur Bestimmung der Akkumulationsraten müssen Proben aus Schneeschächten oder Firn-/Eisbohrkernen genommen, datiert und gewogen werden. Dies ist eine sehr zeitintensive Arbeit und erfordert direkten Zugang zum Untersuchungsgebiet. Daher sind die Akkumulationsraten üblicherweise der am schlechtesten bekannte Parameter hinsichtlich der regionalen Verteilung der zur Bestimmung der Massenbilanz oder Modellierung erforderlichen Datensätze.
Mit den an Eisbohrkernen gemessenen dielektrischen Eigenschaften können Eisbohrkerne sowohl datiert als die Dichte des Eises bestimmt und somit die Akkumulationshistorie rekonstruiert werden. Sie erlauben auch die Übertragung der mittels EMR-Messungen im Eisschild detektierten internen Schichten auf die Eisbohrkerne. Somit können durch Verfolgen von Isochronen, altersgleichen internen Schichten im Eis, die einzelnen Lokationen an denen die Akkumulation bestimmt wurde, miteinander verbunden werden, ohne das dazwischen interpoliert werden muss. Des Weiteren kann aus dem Verlauf der Isochronen abgeleitet werden, wie repräsentativ die jeweils bestimmten Zutragsraten sind.
Mit der Erweiterung des geophysikalischen Instrumentariums der Polarforschungsflugzeuge des Alfred-Wegener-Instituts um ein hochfrequentes FMCW-EMR-System (frequency modulated continuous wave electromagnetic reflexion system) wurde es möglich in den Jahren 2010 und 2012 große Bereiche des nördlichen grönländischen Eisschilds hinsichtlich der internen Struktur in den oberen 150 m in jeweils 2-3 Wochen zu kartieren. 2010 wurde ein engmaschiges Raster von 30 x 60 km2 mit einem Profilabstand von 1 km um die NEEM Tiefbohrung (N 77° 30’ / W 051° 18’) abgedeckt und in der zweiten Messkampagne wurden Profile zwischen den diversen Eisbohrlokation der Nordgrönland Traverse (NGT) des AWIs geflogen. Dabei wurden über 10000 Profilkilometer oberhalb der 2000 m Isohypse des Eisschilds geflogen. Basierend auf diesen Daten werden nun detailliertere Karten der Akkumulationsverteilung der abgedeckten Region als erstellt als es auf Basis der Bohrungen allein möglich ist. Im Vergleich mit diesen neuen Datensatz wird sich zeigen, in wie weit großskalige Klimamodelle die Akkumulationsverteilung wiedergeben und auch aus Satellitenmessungen abgeleitete Akkumulationsverteilungen können validiert werden.
"Changing Polar Regions" - 25th International Congress on Polar Research 2013 GLAZIAL-GEODÄTISCHE LANGZEITSTUDIE (1991-2011) ZU