Glacier Reconstructions Research Articles

Tree-ring-based reconstructions of North American glacier mass balance through the Little Ice Age — Contemporary warming transition

Glacier mass-balance reconstructions provide a means of placing relatively short observational records into a longer-term context. In western North America, mass-balance records span four to five decades and capture a relatively narrow window of glacial behavior over an interval that was dominated by warming and ablation. We use temperature- and moisture-sensitive tree-ring series to reconstruct annual mass balance for six glaciers in the Pacific Northwest and Alaska. Mass-balance models rely on the climatic sensitivity of tree-ring chronologies and teleconnection patterns in the North Pacific. The reconstructions extend through the mid to latter portions of the Little Ice Age (LIA) and explore the role of climate variability in forcing mass balance across multiple environmental gradients. Synchronous positive mass-balance intervals coincide with regional moraine building and solar minima, whereas differences in LIA glacier behavior are related to synoptic climate forcing. Secular warming in the late 19th century to present corresponds with the only multi-decadal intervals of negative mass balance in all glacier reconstructions. This suggests that contemporary retreat in western North America is unique with respect to the last several centuries and that regional patterns of glacier variability are now dominated by global climate forcing.

The Last Glacial Maximum at 44°S documented by a 10Be moraine chronology at Lake Ohau, Southern Alps of New Zealand

Determining whether glaciers registered the classic Last Glacial Maximum (LGM; ∼26,500–∼19,000 yrs ago) coevally between the hemispheres can help to discriminate among hypothesized drivers of ice-age climate. Here, we present a record of glacier behavior from the Southern Alps of New Zealand during the ‘local LGM’ (LLGM). We used 10Be surface-exposure dating methods and detailed glacial geomorphologic mapping to produce a robust chronology of well-preserved terminal moraines deposited during the LLGM near Lake Ohau on central South Island. We then used a glaciological model to estimate a LLGM glacier snowline and atmospheric temperature from the Ohau glacier record.Seventy-three 10Be surface-exposure ages place culminations of terminal moraine construction, and hence completions of glacier advances to positions outboard of present-day Lake Ohau, at 138,600 ± 10,600 yrs, 32,520 ± 970 yrs ago, 27,400 ± 1300 yrs ago, 22,510 ± 660 yrs ago, and 18,220 ± 500 yrs ago. Recessional moraines document glacier recession into the Lake Ohau trough by 17,690 ± 350 yrs ago. Exposure of an ice-molded bedrock bench located inboard of the innermost LLGM moraines by 17,380 ± 510 yrs ago indicates that the ice tongue had receded about 40% of its overall length by that time. Comparing our chronology with distances of retreat suggests that the Ohau glacier terminus receded at a mean net rate of about 77 m yr−1 and its surface lowered by 200 m between 17,690 and 17,380 yrs ago. A long-term continuation of ice retreat in the Ohau glacier catchment is implied by moraine records at the head of Irishman Stream valley, a tributary of the Ohau glacier valley. The Irishman Stream cirque glacier advanced to produce a set of Lateglacial moraines at 13,000 ± 500 yrs ago, implying that the cirque glacier was less extensive prior to that advance.We employed a glaciological model, fit to these mapped and dated LLGM moraines, to derive snowline elevations and temperature parameters from the Ohau glacier record. The modeling experiments indicate that a snowline lowering of 920 ± 50 m and temperature depression of 6.25 ± 0.5 °C below modern values allows for the Ohau glacier to grow to an equilibrium position within the LGM moraine belt. Taken together with a glaciological simulation reported from the Irishman Stream valley, snowlines and temperatures increased by at least ∼520 m and ∼3.6 °C, respectively, between ∼18,000 and ∼13,000 yrs ago.Climate parameters derived from the Ohau glacier reconstruction are similar to those derived from glacier records from Patagonia, to air temperature indicators from Antarctica, as well as to sea-surface temperature and stratification signatures of the Southern Ocean. We think that the best explanation for the observed southern LLGM is that southern winter duration modulated Southern Ocean sea ice, which in turn influenced Southern Ocean stratification and made the surface ocean cooler. Orbitally induced cooling of the Southern Ocean provides an explanation for the LLGM in the Southern Alps having been coincident with the northern LGM. We argue further that the global effect of North Atlantic stadials led to disturbance of Southern Ocean stratification, southward shifts of the subtropical front, and retreat of Southern Alps glaciers. Collapse of Southern Ocean stratification during Heinrich Stadial-1, along with attendant sea-surface warming, triggered the onset of the Last Glacial termination in the Southern Alps of New Zealand.

Glacier and climate reconstruction in the Las Leñas Valley (35°S), Central Argentina

Glacier and climate reconstruction in the Las Leñas Valley (35°S), Central Argentina

The use of glacier reconstruction and modelling approaches to refine cold-phase Quaternary climates of central southern Africa

The use of glacier reconstruction and modelling approaches to refine cold-phase Quaternary climates of central southern Africa

Cirque glacier reconstruction at the eastern margin of the Alps

Cirque glacier reconstruction at the eastern margin of the Alps

Shifting westerlies and precipitation patterns during the Late Pleistocene in southern Africa determined using glacier reconstruction and mass balance modelling

South Africa experiences a range of different climatic regimes and is thus an ideal region to investigate Late Pleistocene environmental and climate change. However, detailed quantifiable palaeoclimate data are sparse in the region. In particular, reliable palaeoclimatic data are essential to resolve ongoing controversies regarding temperature depression and moisture availability during glacial periods in the sub-continent. Small glaciers close to the glaciation threshold are highly sensitive to changes in temperature and precipitation and are therefore ideal indicators of past climatic conditions during their existence. This paper derives some of the first quantitative data on Last Glacial Maximum (LGM) palaeoprecipitation in southern Africa, based on glacier reconstruction and mass balance modelling for the Lesotho Highlands.The reconstruction of former glaciers and their dynamics enables the determination of glacier viability under specific climatic envelopes. Glacier reconstructions at five sites in the Lesotho Highlands yield palaeoglaciers with Equilibrium Line Altitudes (ELAs) ranging from 3095 to 3298 m a.s.l., and reconstructed steady-state mass balance and flow dynamics are comparable with modern analogues. Topoclimatic factors are investigated, with temperature-radiation-index modelling indicating that topographic shading was an important factor determining the existence of small glaciers in this region. The occurrence of glaciation in the Drakensberg during the LGM suggests a potential increase in precipitation and change in its seasonality. Such trends are likely associated with an increased frequency of westerly wave (cold front) disturbances due to the northward shift of pressure belts, which would also increase precipitation as snow at higher altitudes. The application of a high resolution climate model (HadAM3h) to test this, displays a change in the seasonal timing of precipitation during the Last Glacial cycle, with a decrease in precipitation evident during the summer months. This is likely to have had important implications for the mass balance and survival of small niche glaciers in the region, with more precipitation falling during the spring – winter – autumn months as snow.

The Younger Dryas glaciation in the southeastern Monadhliath Mountains, Scotland: glacier reconstruction and palaeoclimate implications

Geomorphological mapping of locally nourished glaciers was conducted in four glens in the southeastern Monadhliath Mountains, Scotland. Three glaciers are interpreted to be of Younger Dryas age based on geomorphological similarity to features in other Scottish upland areas known to have been glaciated during the Younger Dryas, and on comparison to adjacent ice‐free areas in the lower glens where landform‐sediment assemblages typically reflect peri/paraglacial readjustment during the stadial. Here we reconstruct Younger Dryas glacier termini based on moraine alignments and associated geomorphological and sedimentological evidence. An adjacent wide plateau area at high altitude may have permitted extensive ice accumulation, but no unequivocal geomorphological signature is evident. To establish upper glacier limits, a series of ice profiles are modelled. The results yield a range of realistic glacier configurations bracketed between two distinct scenarios: a valley glaciation with the glaciers' upper limit on the plateau edge, and a low‐domed icecap centred on the plateau with ice flowing radially into the lower glens. Reconstructed equilibrium‐line altitudes are 795 m a.s.l. for the valley‐glacier scenario and 894 m a.s.l. for the icecap scenario. Calculated mean ablation‐season temperatures at the ELA are 1.2°C and 0.4°C for the valley‐glacier and the icecap scenario, respectively, from which we infer mean annual precipitation rates between 323 and 520 mm a−1. Palaeoclimate results indicate a stadial climate in central Scotland 65–79% more arid than at present, comparable to that of western Norway for the stadial and to the present‐day Canadian Arctic.

Climate change and rock fall events in high mountain areas: numerous and extensive rock falls in 2007 at mittlerer burgstall, central austria

Kellerer‐Pirklbauer, A., Lieb, G.K.,Avian, M. and Carrivick, J., 2012. Climate change and rock fall events in high mountain areas: numerous and extensive rock falls in 2007 at Mittlerer Burgstall, Central Austria. Geografiska Annaler: Series A, Physical Geography, 94, 597ndash;78. doi:10.1111/j.1468‐0459.2011.00449.Landslides in alpine areas are becoming more frequent. In 2007, a number of rock fall events occurred on the sharp SE‐ridge of the mountain Mittlerer Burgstall (2933 ma.s.l., 47°06′ 07″ N; 12° 42′ 36″ E) completely changing the shape of the mountain. Before the events, the SE‐ridge was sharp with steep rock faces on both sides. The mountain was a nunatak surrounded by two glacier tongues of Pasterze Glacier during the Little Ice Age. In this paper we use geomorphological mapping, permafrost distribution modelling, glacier reconstruction, surface and near‐surface ground temperature data, air temperature data, and airborne laserscanning data to assess these multiple rock fall events. Results show that the entire area of detachment covers 3100 m2. The areas of transportation and deposition cover 85-000m2 partly contributing to the supraglacial debris cover of Pasterze Glacier. The volume of all rock fall deposits is about 56-000m3. Permafrost modelling and ground temperature monitoring indicate that the area of detachment is located near the lower limit of discontinuous permafrost. Permafrost is relatively warm and thin at the summit area of Mittlerer Burgstall with a mean temperature of only –1.0°C at 1.8 m depth in 2007–2010. Substantial surface lowering of the glacier tongues surrounding the mountain on both sides (by −250 and −70 m since the Little Ice Age) changed the stress and strain field in the bedrock. Furthermore, the generally highly fractured bedrock favoured slope instability. The triggering event for the rock falls were most likely the effects of the warm winter of 2006/07 which was 2.2–4.8°C warmer compared to the seven winters before. A monitoring programme regarding future rock falls at Mittlerer Burgstall is ongoing.

A new approach for reconstructing glacier variability based on lake sediments recording input from more than one glacier

We explore the possibility of building a continuous glacier reconstruction by analyzing the integrated sedimentary response of a large (440km2) glacierized catchment in western Norway, as recorded in the downstream lake Nerfloen (N61°56’, E6°52’). A multi-proxy numerical analysis demonstrates that it is possible to distinguish a glacier component in the ~8000-yr-long record, based on distinct changes in grain size, geochemistry, and magnetic composition. Principal Component Analysis (PCA) reveals a strong common signal in the 15 investigated sedimentary parameters, with the first principal component explaining 77% of the total variability. This signal is interpreted to reflect glacier activity in the upstream catchment, an interpretation that is independently tested through a mineral magnetic provenance analysis of catchment samples. Minimum glacier input is indicated between 6700–5700calyr BP, probably reflecting a situation when most glaciers in the catchment had melted away, whereas the highest glacier activity is observed around 600 and 200calyr BP. During the local Neoglacial interval (~4200calyr BP until present), five individual periods of significantly reduced glacier extent are identified at ~3400, 3000–2700, 2100–2000, 1700–1500, and ~900calyr BP.

The Little Ice Age history of the Glacier des Bossons (Mont Blanc massif, France): a new high-resolution glacier length curve based on historical documents

Historical and proxy records document that there is a substantial asynchronous development in temperature, precipitation and glacier variations between European regions during the last few centuries. The causes of these temporal anomalies are yet poorly understood. Hence, highly resolved glacier reconstructions based on historical evidence can give valuable insights into past climate, but they exist only for few glaciers worldwide. Here, we present a new reconstruction of length changes for the Glacier des Bossons (Mont Blanc massif, France), based on unevaluated historical material. More than 250 pictorial documents (drawings, paintings, prints, photographs, maps) as well as written accounts have been critically analysed, leading to a revised picture of the glacier’s history, especially from the mid-eighteenth century up to the 1860s. Very important are the drawings by Jean-Antoine Linck, Samuel Birmann and Eugene Viollet-le Duc, which depict meticulously the glacier’s extent during the vast advance and subsequent retreat during the nineteenth century. The new glacier reconstruction extends back to AD 1580 and proves maxima of the Glacier des Bossons around 1610/1643, 1685, 1712, 1777, 1818, 1854, 1892, 1921, 1941, and 1983. The Little Ice Age maximum extent was reached in 1818. Until the present, the glacier has lost about 1.5 km in length, and it is now shorter than at any time during the reconstruction period. The Glacier des Bossons reacts faster than the nearby Mer de Glace (glacier reconstruction back to AD 1570 available). The Mont Blanc area is, together with the valley of Grindelwald in the Swiss Alps (two historical glacier reconstructions available back to AD 1535, and 1590, respectively), among the two regions that are probably best-documented in the world regarding historical glacier data.

Using the surface profiles of modern ice masses to inform palaeo-glacier reconstructions

Morphometric study of modern ice masses is useful because many reconstructions of glaciers traditionally draw on their shape for guidance. Here we analyse data derived from the surface profiles of 200 modern ice masses—valley glaciers, icefields, ice caps, and ice sheets with length scales from 10 0 to 10 3 km—from different parts of the world. Four profile-attributes are investigated: relief, span, and two parameters C ∗ and C̃ that result from using Nye’s (1952) theoretical parabola as a profile descriptor. C ∗ and C̃ respectively measure each profile’s aspect ratio and steepness, and are found to decrease in size and variability with span. This dependence quantifies the competing influences of unconstrained spreading behaviour of ice flow and bed topography on the profile shape of ice masses, which becomes more parabolic as span increases (with C ∗ and C̃ tending to low values of 2.5–3.3 m 1/2). The same data reveal coherent minimum bounds in C ∗ and C̃ for modern ice masses that we develop into two new methods of palaeo-glacier reconstruction. In the first method, glacial limits are known from moraines, and the bounds are used to constrain the lowest palaeo ice surface consistent with modern profiles. We give an example of applying this method over a three-dimensional glacial landscape in Kamchatka. In the second method, we test the plausibility of existing reconstructions by comparing their C ∗ and C̃ against the modern minimum bounds. Of the 86 published palaeo ice masses that we put to this test, 88% are found to be plausible. The search for other morphometric constraints will help us formalise glacier reconstructions and reduce their uncertainty and subjectiveness.

Glacier reconstruction and mass‐balance modelling as a geomorphic and palaeoclimatic tool

AbstractThe reconstruction of former mountain glaciers has long been used to examine the implications of rapid climate shifts, for example at the last glacial–interglacial transition, and for evaluating asynchronous behaviour of mountain glaciers compared with mid‐latitude ice sheets during the Late Quaternary. Glacier reconstruction has also been used as a source of palaeoclimatic information, based on the recognition of empirical relationships between glaciers and climate. This paper reviews the application and implications of a recently revised method of glacier reconstruction (Carr and Coleman, 2007), based around glaciological principles of mass‐balance. This study examines how this approach can be used to test geomorphological interpretations of former mountain glaciation and also to infer precipitation fields at sites of former glaciation. Sites of Younger Dryas niche and icefield glaciation in the British Isles demonstrate how this method can verify interpretations of marginal glaciation and begin to understand the different behaviour of outlet glaciers within the same environmental regime. Examination of a site of former niche glaciation in Southern Africa demonstrates how glacier reconstruction may be used to infer annual and seasonal precipitation values and strongly supports the idea that winter precipitation in Lesotho and SE South Africa was substantially greater than present‐day values during the last glacial cycle. Copyright © 2010 John Wiley & Sons, Ltd.

A complete record of Holocene glacier variability at Austre Okstindbreen, northern Norway: an integrated approach

Arctic glaciers are currently undergoing major changes, but accurate knowledge about how they varied during the entire Holocene is still scarce. Here we present a new complete glacier record from Austre Okstindbreen in Nordland, northern Norway. This reconstruction is based on a number of short and long cores retrieved from several downstream basins, which have been analyzed by a suite of methods including geochemical elements (XRF), rock magnetic properties, dry bulk density (DBD) and Loss-on-ignition (LOI). Lake sediment distribution was surveyed and mapped prior to coring by the use of ground penetrating radar (GPR). Independently lichen-dated marginal moraines and historical information about the glacier frontal positions from old photographs and maps have made it possible to link the moraine sequence to the 210Pb dated lake sediment chronology. This integrated approach reveals that Austre Okstindbreen is the first known glacier in Scandinavia to possibly have survived the “Holocene Thermal Optimum”. It also brackets the four largest glacier advances to c 7400–7000, 1400–1200, 900–700 and 300–150 years before AD 2000 (b2k). In contrast to most reconstructed glaciers in Scandinavia, the largest glacier advance was not associated with the “Little Ice Age”, but rather to an earlier period centred at 1300 b2k. Both the moraine chronology and the lacustrine records document this Neoglacial advance. Compared to other glacier reconstructions from the Northern Hemisphere, we identify near-synchronous glacier advances occurring roughly at 4000 b2k; 2700 b2k; 1300 b2k and during the “Little Ice Age”. These correlative advances across the Northern Hemisphere suggest that these observed centennial-scale events are a shared feature regardless of the large geographical distances separating them. Some minor discrepancies between different geographical areas may be caused by lack of precise dating, but local climatic conditions may play a role as well.

Reconstruction of the pleistocene glaciers of Mt. Durmitor in Montenegro

Mount Durmitor is situated in the southeastern part of the Dinaric mountain system in Montenegro. Throughout the Pleistocene there were many glaciers there, which descended to adjacent karst plateau. Types of glaciers, their number and direction of moving were mostly affected by geological structure (carbonate basis) and pre-glacial relief (karst and fluvial relief). During two phases of intensive glaciation, the surface that had been seized by glacial changes also changed. Over 54% of the surface of Durmitor was exposed to the glacial process of the stronger phase and about 36% of the weaker phase. Cirque type of glaciation dominated the third phase.

Recognition and palaeoclimatic implications of late Quaternary niche glaciation in eastern Lesotho

AbstractGeomorphic evidence of former glaciation in the high Drakensberg of southern Africa has proven controversial, with conflicting glacial and non‐glacial interpretations suggested for many landforms. This paper presents new geomorphological, sedimentological and micromorphological data, and glacier mass‐balance modelling for a site in the Leqooa Valley, eastern Lesotho, preserving what are considered to be moraines of a former niche glacier that existed during the Last Glacial Maximum (LGM). The geomorphology and macro‐sedimentology of the deposits display characteristics of both active and passive transport by glacial processes. However, micromorphological analyses indicate a more complex history of glacial deposition and subsequent reworking by mass movement processes. The application of a glacier reconstruction technique to determine whether this site could have supported a glacier indicates a reconstructed glacier equilibrium line altitude (ELA) of 3136 m a.s.l. and palaeoglacier mass balance characteristics comparable with modern analogues, reflecting viable, if marginal glaciation. Radiocarbon dates obtained from organic sediment within the moraines indicate that these are of LGM age. The reconstructed palaeoclimatic conditions during the LGM suggest that snow accumulation in the Drakensberg was significantly higher than considered by other studies, and has substantial relevance for tuning regional climate models for southern Africa during the last glacial cycle. Copyright © 2009 John Wiley & Sons, Ltd.

Climate of the Little Ice Age and the past 2000 years in northeast Iceland inferred from chironomids and other lake sediment proxies

A sedimentary record from lake Stora Viðarvatn in northeast Iceland records environmental changes over the past 2000 years. Downcore data include chironomid (Diptera: Chironomidae) assemblage data and total organic carbon, nitrogen, and biogenic silica content. Sample scores from detrended correspondence analysis (DCA) of chironomid assemblage data are well correlated with measured temperatures at Stykkisholmur over the 170 year instrumental record, indicating that chironomid assemblages at Stora Viðarvatn have responded sensitively to past temperature changes. DCA scores appear to be useful for quantitatively inferring past temperatures at this site. In contrast, a quantitative chironomid-temperature transfer function developed for northwestern Iceland does a relatively poor job of reconstructing temperature shifts, possibly due to the lake’s large size and depth relative to the calibration sites or to the limited resolution of the subfossil taxonomy. The pre-instrumental climate history inferred from chironomids and other paleolimnological proxies is supported by prior inferences from historical documents, glacier reconstructions, and paleoceanographic studies. Much of the first millennium AD was relatively warm, with temperatures comparable to warm decades of the twentieth century. Temperatures during parts of the tenth and eleventh centuries AD may have been comparably warm. Biogenic silica concentrations declined, carbon:nitrogen ratios increased, and some chironomid taxa disappeared from the lake between the thirteenth and nineteenth centuries, recording the decline of temperatures into the Little Ice Age, increasing soil erosion, and declining lake productivity. All the proxy reconstructions indicate that the most severe Little Ice Age conditions occurred during the eighteenth and nineteenth centuries, a period historically associated with maximum sea-ice and glacier extent around Iceland.

Loch Lomond Stadial glaciers in North Harris, Outer Hebrides, North-West Scotland: glacier reconstruction and palaeoclimatic implications

Geomorphological mapping of North Harris provides evidence for the former existence of 10 glaciers with a total area of ca 35km2. A Loch Lomond (Younger Dryas) Stadial age (ca 12.9–11.5kyrBP) for this glacial episode is inferred from glacier configuration, landsystems dominated by hummocky recessional moraines, and relationships with Lateglacial periglacial phenomena. Equilibrium line altitudes (ELAs) of 150–289m were calculated for individual glaciers. ELA variability mainly reflects differences in snow-contributing area. The area-weighted mean ELA (204m) is consistent with a northwards decline in ELAs along the western seaboard of the British Isles of 69.5m (100km)−1, equivalent to a northwards ablation-season temperature decrease of 0.42°C (100km)−1. This latitudinal temperature gradient implies a mean July sea-level temperature of ca 7.2°C for the coldest part of the stade, roughly 6°C lower than at present. Sea-level precipitation at the time of the LLS glacial maximum is inferred to have been between ca 1970±200 and 2350±200mmyr−1, implying that LLS precipitation was up to 25% greater than now. Patterns of recessional moraines indicate that the glaciers remained close to climatic equilibrium as they retreated to their sources, though moraine belts implying near-stationary or readvancing ice margins on flat valley floors are separated by moraine-free zones indicating uninterrupted retreat. Calculation of ELAs for ‘residual’ glaciers in former source areas suggests that summer warming of ⩽1.0°C would have resulted in shrinkage of the glaciers to their sources.

Early-Holocene glacier fluctuations in Krundalen, south central Norway: palaeoglacier dynamics and palaeoclimate

Krundalen, a valley occupied by three eastern outlet glaciers of the Jostedalsbre ice cap, contains three groups of moraines, two of which are outside the dated neoglacial (`Little Ice Age', LIA) limits. Exposures in the outermost moraine ridge display three sedimentary units. Detailed sedimentological analyses reveal that the lower two units formed during a temporary stillstand of the ice margin inferred to have occurred because of a topographically controlled stabilization of the ice margin during glacier retreat following the Younger Dryas. A climatically controlled readvance during which the upper unit was deposited, partly eroding pre-existing sediments, followed. Continuation of this readvance led to the whole sequence being pushed up to form the present moraine. The sedimentological results including clast shape measurements imply a temperate glacier thermal regime at the time of moraine formation. The glacial palaeoenvironment was characterized by frequent oscillations and an abundant supply of glaciogenic sediment. The age of this landform can at present not be determined by numerical dating. However, the moraine is likely to have been formed in the early Holocene, during Jondal Event 2 (JE) from c. 10 550—10 450 cal. yr BP. The average equilibrium-line altitude lowering calculated for this event is c. 440 m, 340 m for the Erdalen Event 1 (EE, 10 100—10 050 cal. yr BP) moraines and c. 190 m for the LIA moraines farther upvalley. Precipitation calculated for these stages compared with present values is 160—175% (JE), 165—175% (EE) and 110% (LIA). Summer air temperatures were slightly higher than today's during the JE, much higher during the EE and are indistinguishable from present values during the LIA. The existence of a potential JE-equivalent and the extent of the EE are reported and used for glacier reconstruction for the first time in Krundalen. The sedimentological data implies that the JE did not simply consist of a single readvance but was more complex. It is argued that glacial sedimentology linked with methods of glacier reconstruction provides a powerful tool to gain insights into the dynamics and functioning of formerly glaciated areas.

Critical approach to methods of glacier reconstruction in high Asia and discussion of the probability of a Qinghai-Xizang (Tibetan) inland ice

This overview discusses old and new results as to the controversy on the past glacier extension in High Asia, which has been debated for 35 years now. This paper makes an attempt to come closer to a solution. H.v. Wissmann’s interpretation (1959) of a small-scale glaciation contrasts with M. Kuhle’s reconstruction (1974) of a large-scale glaciation with a 2.4 million km2 extended Qinghai-Xizang (Tibetan) inland glaciation and a Himalaya-Karakorum icestream network. Both opinions find support but also contradiction in the International and Chinese literature (Academia Sinica). The solution of this question is of supraregional importance because of the subtropical position of the concerned areas. In case of large albedo-intensive ice surfaces, a global cooling would be the energetical consequence and, furthermore, a breakdown of the summer monsoon. The current and interglacial heat-low above the very effective heating panel of the Qinghai-Xizang (Tibetan) Plateau exceeding 4000 m, which gives rise to this monsoon circulation, would be replaced by the cold-high of an inland ice. In addition, the plate-tectonically created Pleistocene history of the uplift of High Asia — should the occasion arise up to beyond the snowline (ELA) — would attain a paleoclimatically great, perhaps global importance. In case of a heavy superimposed ice load, the question would come up as to the glacio-isostatic interruption of this primary uplift. The production of the loesses sedimentated in NE-China and their very probable glacial genesis as well as an eustatic lowering of the sea-level by 5 to 7 m in the maximum case of glaciation are immediately tied up with the question of glaciation we want to discuss. Not the least, the problems of biotopes of the sanctuary-centres of flora and fauna, i.e., interglacial re-settlement, are also dependent on it. On the basis of this Quaternary-geomorphological-glaciological connection, future contributions are requested on the past glaciation, the current and glacial permafrost table and periglacial development, the history of uplift, and the development of Ice Age lakes and loess, but also on the development of vegetation and fauna in High Asia.

Morphostratigraphic principles in glacier reconstruction -a perspective from the British Younger Dryas

Glacier reconstruction enables the calculation of palaeoglaciological and palaeoclimatic variables such as the equilibrium-line altitude and palaeo-precipitation values. Such data are important for our understanding of past atmosphere-cryosphere interactions and as input variables to constrain numerical models effectively. Numerical dating is crucial to constrain the age of glacial events, but, due to absence of dateable material and/or contamination problems, ice masses can frequently be constrained satisfactorily only in a few locations. Thus, extrapolation and interpolation of geomorphological evidence is required to establish the extent of glaciers at a given time for the whole ice mass. Using examples from areas in Britain that were last covered by glaciers during the Younger Dryas, geomorphological approaches are reviewed and potential pitfalls highlighted. A multiproxy morphostratigraphic approach that utilizes clear landsystem contrasts inside and outside dated glacial limits is developed and tested in an area where numerical dates are sparse. Landform assemblages suitable in this respect are the type and frequency of moraines, river terrace sequences, glaciofluvial landforms, raised beaches, the upslope terminations of sediment cover (‘drift limits’), periglacial trimlines and periglacial features such as blockfields, solifluction lobes and thick talus accumulations. It is concluded that, if multiple lines of geomorphological evidence converge, these can be used to confine the extent of past glaciers in a given area and to guide dating programmes.