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The Wet Cave vertebrate fossil deposit of the Naracoorte Caves in south-eastern South Australia contains a rich and diverse assemblage of small mammal fauna known to span the Upper Pleistocene–Holocene. Here, we describe five previously unidentifiedin situunits (A, B, C, E and F) and one likely reworked unit (D) in the Wet Cave sedimentary profile, which are correlated with paleoclimatic conditions associated with the Last Glacial Cycle. Additional radiocarbon dates presented here provide a finer temporal resolution for the upper sections of the sequence than previously available and reveal rapid deposition of polished quartz sands laminated with brown silts during the last glacial maximum (LGM). Change in sediment type and depositional processes are dated from 16.8 to 16.4 k cal y BP and are associated with the onset of deglaciation. The characteristics of the fivein situdepositional units are similar to those identified from the contemporaneous fossil and sedimentary sequence of Blanche Cave 3rd Chamber, located approximately 400 m away, reflecting interactions between paleoclimate, sediment mobility and deposition at this locality. Greater variation is evident between the Wet Cave sedimentary profile and the inner chamber of Robertson Cave, located approximately 6 km away and shows that local processes and cave structure exerted some control on sediment accumulation. Paleoclimatic inferences from the depositional sequence of Wet Cave are broadly consistent with those inferred from regional landforms for south-eastern Australia but provide a local signal more suitable for cross-correlation of the fossil faunas. In particular, the Wet Cave sequence suggests that local conditions were relatively stable in the lead up to the LGM despite fluctuation in both local and regional effective precipitation. Sedimentary units associated with the post-LGM deglaciation are characterised by alternating sand and sandy-silt layers, assumed to reflect the impact of enhanced seasonality and/or climatic fluctuation leading towards the Holocene. [ABSTRACT FROM AUTHOR]

The interglacial-glacial decrease in atmospheric methane concentration is often attributed to a strong decline in the wetland source. This seems consistent with the extreme coldness and vastly expanded ice sheets. Here we analyse coupled model simulations for the last glacial maximum from the Paleoclimate Modelling Intercomparison Project, using simple relations to estimate wetland characteristics from the simulated climate and vegetation. It is found that boreal wetlands shift southward in all simulations, which is instrumental in maintaining the boreal wetland source at a significant level. The mean emission temperature over boreal wetlands drops by only a few degrees, despite the strong overall cooling. The temperature effect on the glacial decline in the methane flux is therefore moderate, while reduced plant productivity contributes equally to the total reduction. Moisture effects play a role on the local scale only, while averaging out globally. [ABSTRACT FROM AUTHOR]

Previous studies of clast macrofabrics in glacigenic deposits have concentrated on A-axis orientations and dips, and a variety of control samples are available based upon such measurements. Like clast A-axes, A/B planes will also tend to rotate to parallelism with the direction of shear and therefore should also provide meaningful data on the direction and cumulative impact of shear by the depositing/deforming medium (i.e. glacier ice). The measurement of A/B plane dip and orientation avoids the potential problem of the transverse orientations observed for clast A-axes and provides poles-to-plane data, thereby strengthening the modality of samples and providing clear visual impressions of stress directions. Such data also enable more significant inter-sample comparisons of fabric strength and clast dip angles, which are significant when assessing the impact of shearing in sediment genesis. We present data on clast A/B plane dip directions and angles from subglacial tills, glacitectonite continuums, subglacially lodged clasts and glacimarine/glacilacustrine deposits using traditional methods of statistical and graphical macrofabric analysis. These sample sets will serve as control data for future macrofabric analyses that utilize A/B planes. The separation of the unequivocally lodged clast component from subglacial till samples allows us to demonstrate the influence of deformation and ploughing in the relative weakening of till fabrics as proposed by some researchers. High angles of A/B plane dip in glacigenic subaqueous deposits appear to be well developed in the glacilacustrine setting investigated here, confirming previous studies based on A-axis dips, but less convincing in the glacimarine sediments of the Canadian Arctic, thereby widening the range of fabric strengths in subaqueous glacigenic deposits. Significant overlaps of A/B plane fabric shape envelopes reflect the strain history of subglacial and subaqueous depositional environments, which is unsurprising given the hybrid nature of glacigenic deposits, but the statistical isolation of the lodgement component from subglacial traction tills strongly suggests that the continuum of sample plots on modality/isotropy graphs reflects the range of strain histories in glacitectonites and subglacial traction till. [ABSTRACT FROM AUTHOR]

In this paper we describe the dynamic behaviour of Salajekna, a valley glacier, over the last 200 years using terrestrial observations, in situ measurements, remote sensing observations and glacier reconstructions. The response time of the glacier was calculated using analytical models and field measurements. We were subsequently able to attribute specific dynamic responses to climate trends in the available climate record. The glacier's historical maximum extension was reached around 1880–1910 and was the result of a more continental climate with multi-modal airflows in the late 18th and early 19th centuries. A transition to more maritime conditions in the mid-19th century resulted in a near-continuous 20th century retreat before the glacier adjusted to a near-steady state. [ABSTRACT FROM AUTHOR]

Two well dated Holocene sediment records bordering the Denmark Strait region have been used to reconstruct past climate variability. The content of biogenic silica, clastic and organic material and moss in a lacustrine record from Lake N14 has been used to infer past variability in precipitation and temperature in southern Greenland. Sedimentologic and petrologic composition of sand in a shelf sediment record from the Djúpáll trough is used to infer past variability in the northwestern storm activity on northwestern Iceland, which probably also affected the inflow of polar waters from the East Greenland Current. Our evaluation of these records with a number of previous studies from the region documents Holocene climatic optimum conditions peaking between 8000 and 6500 calendar years before present (cal yr BP). Mid-Holocene climate deterioration set in around 5000 cal yr BP followed by a further marked setback around 3500 cal yr BP. A stacking of climate variability on a centennial timescale from previous studies in the area shows a fairly good correspondence to the timing of marked cold and warm events as evidenced from the Lake N14 and the Djúpáll trough records. Cooler periods are explained as the response to marked incursions of ice-laden polar water from the Arctic Ocean to the Denmark Strait region. Cool northerly and northwesterly winds along the East Greenland coast in relation to frequent strong atmospheric low pressure in the Barents Sea, coupled with strong high pressure over Greenland, would have favoured southward export of polar waters. A comparison with the proxy records of nuclide production (14C and 10Be) suggests that solar activity may have had some influence on the atmospheric pressure distribution in the Denmark Strait region. [ABSTRACT FROM AUTHOR]

Norway and New Zealand both experienced recent glacial advances, commencing in the early 1980s and ceasing around 2000, which were more extensive than any other since the end of the Little Ice Age. Common to both countries, the positive glacier balances are associated with an increase in the strength of westerly atmospheric circulation which brought increased precipitation. In Norway, the changes are also associated with lower ablation season temperatures. In New Zealand, where the positive balances were distributed uniformly throughout the Southern Alps, the period of increased mass balance was coincident with a change in the Interdecadal Pacific Oscillation and an associated increase in El Niño/Southern Oscillation events. In Norway, the positive balances occurred across a strong west-east gradient with no balance increases to the continental glaciers of Scandinavia. The Norwegian advances are linked to strongly positive North Atlantic Oscillation events which caused an overall increase of precipitation in the winter accumulation season and a general shift of maximum precipitation from autumn towards winter. These cases both show the influence of atmospheric circulation on maritime glaciers. [ABSTRACT FROM AUTHOR]

The ice block in Scalrişoara Cave, NW Romania, is preserved due to unusual climate and permafrost conditions within the cave. The air temperature in the cave is governed by the winter cold, the cooling effect of the ice block, and only to a minor extent influenced by summer temperatures. At present, the ice block is slowly thinning, but the present-day climate is sufficiently cold to preserve the permafrost conditions caused by the cold air trapped in the cave. In February 2003 a 22.5 m long ice core was recovered from the ice block. Approximately 200 ice layers have been identified by visual examination. Ice crystallographic analyses indicate a steady growth of ice crystals with depth and there is no sign of deformation. Carbon-14 dates on wood-related samples collected from a natural vertical exposure of the ice block indicate that the ice spans more than 1000 years. Observations on the exposure indicate that a basal melting phase may have occurred in the past. [ABSTRACT FROM AUTHOR]

A new high-resolution, alkenone-derived record of sea-surface temperature (SST) change covering the last 26000 years was obtained from the east-equatorial Atlantic off the Congo River. Temperature fluctuations correspond to climate change recorded in other marine and terrestrial archives of the region. The maximum temperature difference between 26000 years BP ago and the Holocene climate optimum around 6000 years Be was 4.3°C, corroborating other SST estimates from the same area. The coldest conditions were followed by a warming that began at 24000 calendar years BP, a time when Northern Hemisphere ice sheets were still at their maximal position. This comparatively early warming is in agreement with previous findings from the east-equatorial South Atlantic. After a relatively stable period between 21500 and 14500 calendar years Be, a second warming began at 14500 calendar years Be which coincides with the onset of the African Humid Period. A cool period at 11500 calendar years 8P halted this warming but the trend of increasing temperatures began again at 10000 calendar years BP, this time through large-scale oscillations. The warmest time, around 6000 calendar years BP, was followed by a modest cooling that coincides with the end of the African Humid Period and the onset of Neoglaciation on the African continent. Following this the record shows two distinct warming-cooling cycles during the late Holocene. [ABSTRACT FROM AUTHOR]

Crusts of white carbonate precipitate occur commonly on the upper surfaces of glacially sculptured Precambrian granites and gneisses in east-central Ellesmere Island. Radiocarbon dating of 21 such carbonate precipitates, from elevations between 50 m and 1050 m a.s.l., has yielded only Holocene ages. Two samples from Ellesmere Island, plus one from Inglefield Land, Greenland, have calibrated ages over 5000 years, the rest are younger. The formation of these deposits, mainly calcite and characterized by unusually heavy δ13C ratios (+3.36 to +15.18‰), has apparently been aided in some cases by the presence of bacteria, and some crusts seem to have developed where Ca-bearing minerals are more prevalent. In the case of Bache Peninsula and Cape Herschel, where the carbonate crusts are particularly abundant, the presence of calcareous till may have played a role as well. The carbonate crusts may be related to the presence of small, thin carapace ice caps, when such features formed at lower elevations than those at which they exist today. The more extensive cover of ice and snow is postulated to have existed during the latter, cooler part of the Holocene, especially during the period from 2500 to 100 years ago, deduced as a period of low melt from ice core studies on the Agassiz Ice Cap, 200 km to the north. The existence of carapace ice caps at lower elevations also agrees with the radiocarbon evidence for outlet glacier advances during the last 2000 years on both east and west margins of the Prince of Wales Icefield. Alternatively, the white carbonate crusts may be, to a large degree, the result of weathering processes. In either case they provide minimum ages for the exposed, ice-sculptured rock surfaces on which they occur. [ABSTRACT FROM AUTHOR]

The morphometry of 432 glacial cirques in the Maritime Alps (Western French-Italian Alps), studied over several years of fieldwork, was analysed with the use of a geographical information system. Some of the parameters automatically evaluated from digital elevation models required an objective and relatively new definition. In particular, cirque length was measured along a line that, from the threshold midpoint, splits the cirque into two equivalent surfaces; cirque width was automatically drawn as the longest line inscribed in the cirque and perpendicular to the length line. Significant correlations were found among the different factors and parameters analysed. In particular, cirque shape analysis showed that cirques develop allometrically in the three dimensions, i.e. more in length and width than in altitudinal range. Nevertheless cirques of the Maritime Alps have a regular, almost circular shape (meanL/Wvalue= 1.07). The correlations among length, width and area are all very high (r2= 0.8–0.9). In terms of size, cirques show a wide range in area from 0.06 to 5.2 km2 with a mean value of 0.4 km2. The largest cirques are found on SSW-facing slopes and at high elevations. Small cirques can be found at all altitudes but all those at high elevation are part of compound cirques at the main head valleys. Most cirques (37%) are characterized by a northern aspect; NE and SW are also frequent directions. [ABSTRACT FROM AUTHOR]

ABSTRACT. Documentary data provide long time series and sometimes high-resolution, detailed data from historical times to the present and can give valuable information about palaeoclimate, and for the prediction of future climates. In this paper, documentary data containing qualitative information on climate, in the form of a diary written by the farmer I.G. Grude, and two newspapers, were used for the reconstruction of the palaeoclimate at Jaeren, in the county of Rogaland, in southwestern Norway, during the period 1821-50. An index method to quantify the qualitative climate data was developed and used for a low-resolution reconstruction of winter, summer and annual temperatures. A high-resolution climate reconstruction of temperature and precipitation for the winter of 1837/38 is also presented, making use of a method that keeps the climate data in a qualitative form. The climate reconstructions are compared to an instrumental temperature series from Bergen, for the same period. The two data sets are in good agreement except for summer temperature (annual temperature: r = 0.75, winter temperature: r = 0.77, summer temperature: r = 0.44). Compared to average temperatures during 1961-90, the instrumental data from Bergen during the 1821-50 period show slightly different temperatures: annual average was 0.3 Celsius lower, winter 0.4 Celsius lower, and summer 0.1 Celsius lower than at present, implying conditions consistent with the "Little Ice Age" climate. [ABSTRACT FROM AUTHOR]

Colluvial mantles on the mountains of southwestern United States are believed to have formed during colder climates associated with the last glaciation. They imply mean temperatures 10-11°C. lower than those of today and a depression of the timber line by 1,300-1,400 meters. Evaporation rates were about half the present values and by estimating runoff it is possible to reconstruct the full-glacial hydrologic budget of Pleistocene closed lakes. Precipitation was eighty to ninety percent of present values and there was no glacial pluvial. Pollen data can be reconciled with the proposed cold dry climate which has modem homoclimes at higher altitudes and latitudes. [ABSTRACT FROM AUTHOR]