Age determination of sediment cores from the western Svalbard margin

The deglaciation of the continental shelf to the west of Spitsbergen and the main fjord, Isfjorden, is discussed based on sub-bottom seismic records and sediment cores. The sea floor on the shelf to the west of Isfjorden is underlain by less than 2 m of glaciomarine sediments over a firm diamicton interpreted as till. In central Isfjorden up to 10 m of deglaciation sediments were recorded, whereas in cores from the innermost tributary, Billefjorden, less than a meter of ice proximal sediments was recognized between the till and the 'normal' Holocene marine sediments. We conclude that the Barents Sea Ice Sheet terminated along the shelf break during the Late Weichselian glacial maximum. Radiocarbon dates from the glaciomarine sediments above the till indicate a stepwise deglaciation. Apparently the ice front retreated from the outermost shelf around 14.8 ka. A dramatic increase in the flux of line-grained glaciomarine sediments around 13 ka is assumed to reflect increased melting and/or current activity due to a climatic warming. This second stage of deglaciation was interrupted by a glacial readvance culminating on the mid-shelf area shortly after 12.4 ka. The glacial readvance, which is correlated with a simultaneous readvance of the Fennoscandian ice sheet along the western coast of Norway, is attributed to the so-called 'Older Dryas' cooling event in the North Atlantic region. Following this glacial readvance the outer part of Isfjorden became rapidly deglaciated around 12.3 ka. During the Younger Dryas the inner fjord branches were occupied by large outlet glaciers and possibly the ice front terminated far out in the main fjord. The remnants of the Barents Sea Ice Sheet melted quickly away as a response to the Holocene warming around 10 ka.

Investigation of Quaternary foraminifera in sediment core CRP-1 from the Ross Sea, Antarctica

Foraminifera are examined in twenty-six samples from a 44 metre succession of Quaternary glacial sediments recovered from the CRP-1 drillhole on Roberts Ridge, southwestern Ross Sea, Antarctica. In situ marine assemblages were documented in at least three of the six lithostratigraphic units, and it is likely that the remaining three interbedded diamicton units are also marine in origin. Peak foraminiferal diversities are documented in Unit 3.1 (73 species) and Unit 2.2 (32 species). Calcareous benthics dominate the assemblages, but may be accompanied by abundant occurrences of the planktonic Neogloboquadrina pachyderma. Low diversity agglutinated faunas appear in the uppermost strata of Units 4.1 and 2.2. A close relationship between lithofacics and foraminiferal biofacies points to marine environments that alternated between proximity to and distance from active glaciers and iceshelf fronts, with associated variations in salinity, sea-surface ice cover and the levels of rainout from debris-laden ice.

Zur Höhenänderung von Ostalpengletschern im Zeitraum 1969-1979

Eight selected glaciers in the Eastern Alps with a total area of 52 qkm have been surveyed photogrammetrically in the years 1969 and 1979, to determine the annual height change of the glacier surface by the comparison of the two different surveys. In this period of ten years the glaciers show, except for the Hintereisferner, a positive annual height change. But it is less than the change in the past period from 1959 to 1969. The increase in elevation happens mainly in the lower regions of the glaciers, while the glacier-snow-fields don't show any remarkable height changes. So the glacier advance of the sixties seem to have already reached or crossed its maximum.

(Table 2) Chemical composition of ice-rafted brecciated crystalline schist and biotite-garnet crystalline schist from the Kara Sea

Composition and distribution.of ice-rafted coarse debris from the Kara Sea bottom were investigated. This material was obtained on 42 stations in Cruise 49 of R/V Dmitry Mendeleev by Sigsby trawls, box corers, grabs, and gravity corers. Existence of two main petrographic provinces is suggested: (1) West Kara and (2) East Kara. They differ in composition and sources of debris material. It is supposed that debris was transported mainly by floating ice. In Upper Pleistocene time rafting by glaciers and icebergs was also very possible.

Stable carbon and nitrogen isotopic ratios of cores from the Bering Sea

Stable carbon and nitrogen isotopic ratios (d13C and d15N) of organic matter were measured in three sediment cores from deep basins of the Bering Sea to investigate past changes in surface nutrient conditions. For surface water reconstructions, hemipelagic layers in the cores were distinguished from turbidite layers (on the basis of their sedimentary structures and 14C ages) and analyzed for isotopic studies. Although d13C profiles may have been affected by diagenesis, both d15N and d13C values showed common positive anomalies during the last deglaciation. We explain these anomalies as reflecting suppressed vertical mixing and low nutrient concentrations in surface waters caused by injection of meltwater from alpine glaciers around the Bering Sea.

Map of Cordilleera Real Nord (Illampu)

Glacier maps 1 : 50000 exist of the glaciers around lllampu (6368 m) from surveys in 1928, 1963 and 1975, of the glaciers of IIlimani (6420 m) in 1975 and 1983, respectively. From these maps glacier changes 1928 - 1963 - 1975 - 1983 have been evaluated. Their retreat is smaller than that of corresponding glaciers in the Eastern Alps. The alpine advance that has begun in the sixties was not observed in the Cordillera Real.

Ice loss in the Canadian Arctic Archipelago

Though much attention has been focused in recent years on the melting of ice from Greenland and Antarctica, nearly half of the ice volume currently being lost to the ocean is actually coming from other mountain glaciers and ice caps. Ice loss from a group of islands in northern Canada accounts for much of that volume. In a study published in April 2011 in the journal Nature, a team of researchers led by Alex Gardner of the University of Michigan found that land ice in both the northern and southern Canadian Arctic Archipelago has declined sharply. The maps above show ice loss from surface melting for the northern portion of the archipelago from 2004-2006 (left) and 2007-2009 (right). Blue indicates ice gain, and red indicates ice loss. In the six years studied, the Canadian Arctic Archipelago lost an average of approximately 61 gigatons of ice per year. (A gigaton is a billion tons of ice.) The research team also found the rate of ice loss was accelerating. From 2004 to 2006, the average mass loss was roughly 31 gigatons per year; from 2007 to 2009, the loss increased to 92 gigatons per year. Gardner and colleagues used three independent methods to assess ice mass, all of which showed the same trends. The team used a model to estimate the surface mass balance of ice and the amount of ice discharged. They also compiled and analyzed measurements from NASA's Ice, Cloud and Land Elevation Satellite (ICESat) to assess changes in the surface height of ice. Finally, they gathered observations from NASA's Gravity Recovery and Climate Experiment (GRACE) to determine changes in the gravity field in the region, an indicator of the amount of ice gained or lost. The Canadian Arctic Archipelago generally receives little precipitation, and the amount of snowfall changes little from year to year. But the rate of snow and ice melting varies considerably, so changes in ice mass come largely from changes in summertime melt. During the 2004 to 2009 study period, the Canadian Arctic Archipelago experienced four of its five warmest years since 1960, likely fueling the melting. Gardner notes that from 2001 to 2004, the sum of melting from all mountain glaciers and ice caps around the world (but not the Greenland and Antarctic ice sheets) contributed an estimated 1 millimeter per year to global sea level rise. Recent estimates suggest the Greenland and Antarctic ice sheets add another 1.3 millimeters per year to sea level. "This means 1 percent of the land ice volume-mountain glaciers and ice caps-account for about half of all ice loss to the world's oceans," Gardner said. "Most of the ice loss is coming from the Canadian Arctic Archipelago, Alaska, Patagonia, the Himalayas, and the smaller ice masses surrounding the main Greenland and Antarctic ice sheets."

Pollen records from two outcrop profiles in the Kakitu Mountain of Tibet

There is a great similarity between pollen types which occur in the early Holocene NE Tibetan pollen spectra and those which are commonly considered to be typical for the Würm Late Glacial period in Central Europe and for the Würm Pleniglacial period in Southern Europe. Evidently, this similarity is due to a remarkable general conformity of plant taxa growing in cold-arid regions of the northern hemisphere. The improvement of the climate and the retreat of the glaciers that commenced at the end of the Würm period had already terminated definitely before 9500 BP. In addition, the climatic situation as well as the vegetation belts must have remained rather constant during the following 3000 yr, i.e. through most parts of the climatic optimum of the Holocene.

Oxygen- and carbon-isotopes at DSDP Leg 73 Holes

We established a composite oxygen- and carbon-isotope stratigraphy for the Pliocene in the central South Atlantic. Monospecific samples of benthic and planktonic foraminifers from pelagic sediments from DSDP Sites 519, 521, 522, and 523 were analyzed isotopically. The resulting benthic oxygen-isotope stratigraphy allowed three paleoclimatic periods in the Pliocene to be distinguished. During the early Pliocene (5.2-3.3 Ma), low-amplitude climatic changes prevailed in a world that was less glaciated than during the Pleistocene. A net increase in global ice volume is documented in a 0.5 permil positive shift in the average 18O composition of the benthic foraminifers at 3.2 Ma. The middle Pliocene (3.3-2.5 Ma) is not only characterized by a more widespread glaciation of the Southern and Northern hemispheres but also by more drastic isotopic differences between glacial and interglacial times. A minor shift in the average 18O composition of the benthic foraminifers marks the beginning of the late Pliocene-early Pleistocene climatic period (2.5-1.1 Ma). Alternating cold and warm climate is documented in both the oxygen-isotope record and in the pelagic sediments. During cold periods, sediments with a lower CaCO3 content indicate more corrosive bottom-water conditions. More negative 13C signals in the benthic foraminifers from these sediments suggest that the Antarctic Bottom Water current was intensified in glacial times. The oxygen-isotope composition of the measured planktonic foraminifers suggests that the surface water in this part of the South Atlantic remained relatively warm during the growth of the Pliocene glaciers.

High-resolution ice thickness and bed topography of a land-terminating section of the Greenland Ice Sheet, with links to GeoTIFFs and text files

We present ice thickness and bed topography maps with a high spatial resolution (250-500 m) of a land-terminating section of the Greenland Ice Sheet derived from ground-based and airborne radar surveys. The data have a total area of ~12 000 km^2 and cover the whole ablation area of the outlet glaciers of Isunnguata Sermia, Russell, Leverett, Ørkendalen and Isorlersuup up to the long-term mass balance equilibrium line altitude at ~1600 m above sea level. The bed topography shows highly variable subglacial trough systems, and the trough of Isunnguata Sermia Glacier is overdeepened and reaches an elevation of ~500 m below sea level. The ice surface is smooth and only reflects the bedrock topography in a subtle way, resulting in a highly variable ice thickness. The southern part of our study area consists of higher bed elevations compared to the northern part. The compiled data sets of ground-based and airborne radar surveys cover one of the most studied regions of the Greenland Ice Sheet and can be valuable for detailed studies of ice sheet dynamics and hydrology.

Pollen record of sediment profile NERO from Russia

(of book) Problems of origin of the hydrosphere, history of formation and development of underground water, of the World Ocean, lakes, rivers, surface and subsurface ice are under consideration in the book. An attempt of the complete reconstruction of the continental hydrosphere in the Eastern Europe in Late Pleistocene is made. Methods of paleohydrologic studies are described. Some papers are devoted to paleoclimatic problems of river runoff formation and paleotermic evolution of continental glaciers.

Surface water properties, phytoplankton composition and photosynthesis rates of Amundsen Sea sites

The phytoplankton community composition and productivity in waters of the Amundsen Sea and surrounding sea ice zone were characterized with respect to iron (Fe) input from melting glaciers. High Fe input from glaciers such as the Pine Island Glacier, and the Dotson and Crosson ice shelves resulted in dense phytoplankton blooms in surface waters of Pine Island Bay, Pine Island Polynya, and Amundsen Polynya. Phytoplankton biomass distribution was the opposite of the distribution of dissolved Fe (DFe), confirming the uptake of glacial DFe in surface waters by phytoplankton. Phytoplankton biomass in the polynyas ranged from 0.6 to 14 µg Chl a / L, with lower biomass at glacier sites where strong upwelling of Modified Circumpolar Deep Water from beneath glacier tongues was observed. Phytoplankton blooms in the polynyas were dominated by the haptophyte Phaeocystis antarctica, whereas the phytoplankton community in the sea ice zone was a mix of P. antarctica and diatoms, resembling the species distribution in the Ross Sea. Water column productivity based on photosynthesis versus irradiance characteristics averaged 3.00 g C /m**2/d in polynya sites, which was approximately twice as high as in the sea ice zone. The highest water column productivity was observed in the Pine Island Polynya, where both thermally and salinity stratified waters resulted in a shallow surface mixed layer with high phytoplankton biomass. In contrast, new production based on NO3 uptake was similar between different polynya sites, where a deeper UML in the weakly, thermally stratified Pine Island Bay resulted in deeper NO3 removal, thereby offsetting the lower productivity at the surface. These are the first in situ observations that confirm satellite observations of high phytoplankton biomass and productivity in the Amundsen Sea. Moreover, the high phytoplankton productivity as a result of glacial input of DFe is the first evidence that melting glaciers have the potential to increase phytoplankton productivity and thereby CO2 uptake, resulting in a small negative feedback to anthropogenic CO2 emissions.