Age of the Pomeranian ice‐marginal position in northeastern Germany determined by Optically Stimulated Luminescence (OSL) dating of glaciofluvial sediments

Lüthgens, C., Böse, M. & Preusser, F. 2011: Age of the Pomeranian ice‐marginal position in northeastern Germany determined by Optically Stimulated Luminescence (OSL) dating of glaciofluvial sediments. Boreas, 10.1111/j.1502‐3885.2011.00211.x. ISSN 0300‐9843 The Pomeranian ice margin is one of the most prominent ice‐marginal features of the Weichselian glaciation in northern Europe. Previous results of surface‐exposure dating (SED) of this ice margin disagree with established chronologies and ice retreat patterns, i.e. are much younger than previously expected. We crosscheck the age of the Pomeranian ice‐marginal position in northeastern Germany using single‐grain quartz Optically Stimulated Luminescence (OSL) dating of glaciofluvial sediments. OSL dating indicates an active ice margin between 20.1±1.6 ka and 19.4±2.4 ka forming outwash plains attributed to the Pomeranian ice‐marginal position. On the basis of these results, we suggest a critical reassessment of previous SED data available for the Pomeranian ice‐marginal position within their respective regional geomorphological contexts. From a process‐based point of view, SED ages derived from glacigenic boulders document the stabilization of the landscape after melting of dead ice and landscape transformation under periglacial conditions rather than the presence of an ice margin. SED indicates a first phase of boulder stabilization at around 16.4±0.7 ka, followed by landscape stabilization within the area attributed to the recessional Gerswalder subphase around 15.2±0.5 ka. A final phase of accumulation of glaciolacustrine and glaciofluvial sediments at around 14.7±1.0 ka documents the melting of buried dead ice at that time.     

Thermal properties and coal rank in rocks and coal seams of the southern Sydney Basin,new South Wales: A palaeogeothermal explanation of coalification

Measurements of thermal conductivity on 106 disc specimens of rocks from 275 m of the Permian to Triassic section of the Southern Coalfield of the southern Sydney Basin have been carried out in an effort to explain a high rank gradient in the Permian coals. The samples came from six diamond drill holes north and west of Wollongong, although one hole only provided specimens of a syenitic sill (n = 17, mean thermal conductivity = 2.36 W/m°K, s.d. 0.03). When combined with previously published data on chip specimens, with which there is good agreement, from a further four drill holes the mean thermal conductivity for the late Permian and early Triassic sandstones and shales is 3.20 W/m°K.Heat generation by Permian volcanic rocks below the coal measures (from about 1 to 3 μW/m³), and by basement granitic rocks, appears to be consistent with previously reported heat flow for the southern Sydney Basin (about 80 mW/m²). This heat flow is a relatively high value for the east coast of Australia. Younger (Mesozoic and Tertiary) intrusive and extrusive igneous rocks produce local coal-rank anomalies, but do not appear to have any regional effect.The rank of coals above the Permian volcanic rocks appears to be little affected by the presence of the igneous rocks and the coal-rank decreases towards the major area of vulcanicity. Organic matter in sedimentary rocks interbedded with the volcanic rocks is of relatively high rank but it appears that these thermal effects do not extend more than about 100 m above the base of the coal measures. The area of high rank north and northwest of Wollongong seems likely to be a regional effect associated with a combination of high heat generation in basement and the Permian rocks, and high heat flow from the basement. Greater cover on the coal measures, together with an increase in the proportion of rocks of relatively low thermal conductivity in the cover, may also influence the rank in the Permian coal.     

Private sector involvement in urban governance: The case of Business Improvement Districts and Town Centre Management partnerships in England

Although it has many merits, the voluminous literature on urban governance gives scant attention to the actual involvement and positioning of business elites and businesses within Public-Private Partnerships. There is also little consensus among academics as to why the private sector become involved in such schemes. This paper begins to address these issues through a critical empirical examination of how and why the private sector is involved with three English Town Centre Management (TCM) partnerships and the Business Improvement District (BID) subsidiaries all three partnerships have recently developed. In order to do this, the empirical study is guided by a conceptual framework that foregrounds the relationship between (a) the opening up and monitoring of ‘institutional space’ by partnerships and the state, and (b) the motivations and ‘constrained agency’ of the business elites. The paper demonstrates that the positioning of the private sector is more multifarious and fractured than previous studies of urban governance have suggested. It also reveals that business elites and businesses view their participation as an ‘investment’ that needs to accrue significant financial returns and that partnership and state officials are highly selective in their choice of ‘who governs’.     

Improved barometric and loading efficiency estimates using packers in monitoring wells

Measurement of barometric efficiency (BE) from open monitoring wells or loading efficiency (LE) from formation pore pressures provides valuable information about the hydraulic properties and confinement of a formation. Drained compressibility (α) can be calculated from LE (or BE) in confined and semi-confined formations and used to calculate specific storage (S _s). S _s and α are important for predicting the effects of groundwater extraction and therefore for sustainable extraction management. However, in low hydraulic conductivity (K) formations or large diameter monitoring wells, time lags caused by well storage may be so long that BE cannot be properly assessed in open monitoring wells in confined or unconfined settings. This study demonstrates the use of packers to reduce monitoring-well time lags and enable reliable assessments of LE. In one example from a confined, high-K formation, estimates of BE in the open monitoring well were in good agreement with shut-in LE estimates. In a second example, from a low-K confining clay layer, BE could not be adequately assessed in the open monitoring well due to time lag. Sealing the monitoring well with a packer reduced the time lag sufficiently that a reliable assessment of LE could be made from a 24-day monitoring period. The shut-in response confirmed confined conditions at the well screen and provided confidence in the assessment of hydraulic parameters. A short (time-lag-dependent) period of high-frequency shut-in monitoring can therefore enhance understanding of hydrogeological systems and potentially provide hydraulic parameters to improve conceptual/numerical groundwater models.     

Genesis of basalt-hosted massive sulphide deposits from the Trondheim and Sulitjelma districts,Norway: ore lead isotopic considerations

Lead isotopic ratios of bulk sulphides from eleven stratigraphically equivalent deposits from the Köli Nappe sequence in the Trondheim district, and eleven from the Köli sequence at Sulitjelma Norway, have been determined. When plotted on ²⁰⁷Pb/²⁰⁴Pb-²⁰⁶Pb/²⁰⁴Pb diagrams, the data define a linear trend extending from the mantle to the upper crustal model growth curves of Doe and Zartman (1979). Moreover, the data from both districts lie on the same trend. This isotopic trend is interpreted as resulting from the mixing of lead from a mantle source (probably the host basalts) with that of an upper-crustal end member (either sialic basement or the terrigenous sediments surrounding the host basalts). It is also concluded that the deposits in both camps formed more or less contemporaneously. The isotopic mixing line is comparable with that obtained from Besshi ore pyrites in Japan, for which an aulacogenic depositional environment, similar to that found today in the Gulf of California, has been proposed (Fox 1984). It is concluded that a similar depositional environment was responsible for the Trondheim and Sulitjelma ores, although an ensialic back-arc basin, or other possible environments, cannot be entirely ruled out.     

Climate Change and Winter Wheat Management: A Modelling Scenario for South-Eastern England

Crop models are useful tools for assessing the impact of climate change on crop production. The dynamic crop-growth model, CERES-Wheat is used to examine crop management responses, including yield, under six climate change scenarios for the years 2025 and 2050 on the Estate of Imperial College at Wye, Kent, U.K. Sensitivity analysis shows a dry matter yield decrease in response to increases in temperature alone. CERES-Wheat was then constrained to assess the crop performance under water-limited production scenarios with different soils, and the results show that crop grain yield actually increases, largely due to CO₂ fertilisation leading to increased rates of photosynthesis. Different management practices (planting dates and nitrogen application) were applied to find the best adaptation strategies. In general, `early' sowing (10th September) had the highest simulated yield, and `late' sowing (10th November) the lowest. For the soils tested, the highest and sustained crop production was obtained from Hamble soils (silt loam) compared with either the Fyfield (sandy) or Denchworth (clay). Adding nitrogen and other fertilisers would likely be necessary to take full advantage of the CO₂ fertilisationeffect and to compensate, in some cases, for yield losses caused by climate change where water shortage becomes serious.     

Sub-Saharan Northern African climate at the end of the twenty-first century: forcing factors and climate change processes

A regional climate model, the Weather Research and Forecasting (WRF) Model, is forced with increased atmospheric CO₂ and anomalous SSTs and lateral boundary conditions derived from nine coupled atmosphere–ocean general circulation models to produce an ensemble set of nine future climate simulations for northern Africa at the end of the twenty-first century. A well validated control simulation, agreement among ensemble members, and a physical understanding of the future climate change enhance confidence in the predictions. The regional model ensembles produce consistent precipitation projections over much of northern tropical Africa. A moisture budget analysis is used to identify the circulation changes that support future precipitation anomalies. The projected midsummer drought over the Guinean Coast region is related partly to weakened monsoon flow. Since the rainfall maximum demonstrates a southward bias in the control simulation in July–August, this may be indicative of future summer drying over the Sahel. Wetter conditions in late summer over the Sahel are associated with enhanced moisture transport by the West African westerly jet, a strengthening of the jet itself, and moisture transport from the Mediterranean. Severe drought in East Africa during August and September is accompanied by a weakened Indian monsoon and Somali jet. Simulations with projected and idealized SST forcing suggest that overall SST warming in part supports this regional model ensemble agreement, although changes in SST gradients are important over West Africa in spring and fall. Simulations which isolate the role of individual climate forcings suggest that the spatial distribution of the rainfall predictions is controlled by the anomalous SST and lateral boundary conditions, while CO₂ forcing within the regional model domain plays an important secondary role and generally produces wetter conditions.     

Spatial drought reconstructions for central High Asia based on tree rings

Spatial reconstructions of drought for central High Asia based on a tree-ring network are presented. Drought patterns for central High Asia are classified into western and eastern modes of variability. Tree-ring based reconstructions of the Palmer drought severity index (PDSI) are presented for both the western central High Asia drought mode (1587–2005), and for the eastern central High Asia mode (1660–2005). Both reconstructions, generated using a principal component regression method, show an increased variability in recent decades. The wettest epoch for both reconstructions occurred from the 1940s to the 1950s. The most extreme reconstructed drought for western central High Asia was from the 1640s to the 1650s, coinciding with the collapse of the Chinese Ming Dynasty. The eastern central High Asia reconstruction has shown a distinct tendency towards drier conditions since the 1980s. Our spatial reconstructions agree well with previous reconstructions that fall within each mode, while there is no significant correlation between the two spatial reconstructions.     

Tree-ring reconstructed summer temperature anomalies for temperate East Asia since 800 C.E.

We develop a summer temperature reconstruction for temperate East Asia based on a network of annual tree-ring chronologies covering the period 800–1989 C.E. The East Asia reconstruction is the regional average of 585 individual grid point summer temperature reconstructions produced using an ensemble version of point-by-point regression. Statistical calibration and validation tests indicate that the regional average possesses sufficient overall skill to allow it to be used to study the causes of temperature variability and change over the region. The reconstruction suggests a moderately warm early medieval epoch (ca. 850–1050 C.E.), followed by generally cooler ‘Little Ice Age’ conditions (ca. 1350–1880 C.E.) and 20th century warming up to the present time. Since 1990, average temperature has exceeded past warm epochs of comparable duration, but it is not statistically unprecedented. Superposed epoch analysis reveals a volcanic forcing signal in the East Asia summer temperature reconstruction, resulting in pulses of cooler summer conditions that may persist for several years. Substantial uncertainties remain, however, particularly at lower frequencies, thus requiring caution and scientific prudence in the interpretation of this record.     

Identifying hot spots of security vulnerability associated with climate change in Africa

Given its high dependence on rainfed agriculture and its comparatively low adaptive capacity, Africa is frequently invoked as especially vulnerable to climate change. Within Africa, there is likely to be considerable variation in vulnerability to climate change both between and within countries. This paper seeks to advance the agenda of identifying the hot spots of what we term “climate security” vulnerability, areas where the confluence of vulnerabilities could put large numbers of people at risk of death from climate-related hazards. This article blends the expertise of social scientists and climate scientists. It builds on a model of composite vulnerability that incorporates four “baskets” or processes that are thought to contribute to vulnerability including: (1) physical exposure, (2) population density, (3) household and community resilience, and (4) governance and political violence. Whereas previous iterations of the model relied on historical physical exposure data of natural hazards, this paper uses results from regional model simulations of African climate in the late 20th century and mid-21st century to develop measures of extreme weather events—dry days, heat wave events, and heavy rainfall days—coupled with an indicator of low-lying coastal elevation. For the late 20th century, this mapping process reveals the most vulnerable areas are concentrated in Chad, the Democratic Republic of the Congo, Niger, Somalia, Sudan, and South Sudan, with pockets in Burkina Faso, Ethiopia, Guinea, Mauritania, and Sierra Leone. The mid 21st century projection shows more extensive vulnerability throughout the Sahel, including Burkina Faso, Chad, Mali, northern Nigeria, Niger, and across Sudan.