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Abstract: There is a current need to develop annual/decadal chronologies from periods of rapid climate change in order to understand the rate and timing of climate events and identify how other proxies either lead or lag this climate forcing. Annually-laminated or varved sediments are key proxies for understanding environmental change at such a scale. This paper presents the results of microscale analysis of glaciolacustrine varve sediments from Scotland and develops a new index called varve group, which ranks the number of pulses of sediment observed in the summer component of the varve. The varve group index is compared with data from the Greenland ice-core record and correspondence can be observed between the oxygen isotope records from Greenland during the latter part of GS-1 and the 515-year Lochaber varve group index. The processes that control the number of sediment pulses into the lake basin are discussed and we examine how these factors might control both the isotopic composition of the ice cores and varve group formation. It is proposed that the position of the sea ice in the North Atlantic may provide such a mechanism. [Copyright &y& Elsevier]

Abstract: Little has challenged our understanding of climate change more so than the abruptness with which large-scale shifts in temperature occurred during the Late Quaternary. The causal mechanisms driving these rapid changes are poorly understood, largely due to the inherent difficulties of integrating palaeoclimate records which represents the key focus of the INTIMATE 1 [1] INTIMATE: INTegration of Ice, MArine and TErrestrial record is a core project of the INQUA Palaeoclimate Commission. Australasian and North Atlantic projects are currently active. This paper refers specifically to the objectives of the North Atlantic group. project. Tephrochronology has become central to the synchronisation goals of INTIMATE, the overall aim of which is to test the degree of climatic synchroneity in relation to these rapid climatic events. Here we present a European framework of 12 volcanic events that hold considerable promise for achieving the INTIMATE goals and effecting precise correlation of widespread palaeoarchives. These tephras are widespread and fall stratigraphically in close association to rapid climatic changes. We believe that these represent the most valuable tephras for the European INTIMATE project, but also highlight those that require urgent investigation to refine their geochemical signatures, eruptive context and chronological and stratigraphical uncertainties. For instance, new data are presented for the Saksunarvatn Ash that question the sole reliance on major-element analysis for tephra characterisation and highlights some of the challenges that remain for tephra studies. Accordingly, we outline a number of key recommendations relating to geochemical characterisation, data comparison, assessing the depositional integrity of tephra horizons as well as methods for improving age estimates – all of which will optimise the application of tephrochronology to meet the INTIMATE goals. [Copyright &y& Elsevier]

Abstract: Regarding fluvial response to recent climate change, it is important to identify and understand previous changes of fluvial dynamics related to past climatic shifts. In this paper, periods of increased flood activity in Central Tunisian river systems are presented. Changes in Holocene flood dynamics are reconstructed through a comprehensive analysis of 195 radiocarbon dates from alluvial archives. Holocene floodplain deposits in Central Tunisia normally consists of cohesive overbank fines, which exhibit excellent preservation conditions against lateral erosion and, therefore, permit chronostratigraphic records of the entire Holocene at most. Based on published radiocarbon dates, two 14C cumulative probability density plots are created for Central Tunisia: the former represents ‘activity dates’ indicating phases of increased fluvial dynamics, the latter documents ‘stability dates’ showing periods of soil formation and enhanced landscape stability within the floodplain and the catchment. Due to geomorphological considerations, ‘activity dates’ and ‘stability dates’ should be mutually exclusive. There is a good match for the Mid-Holocene with increased periods of flooding from 6.2 to 6.0, 4.8 to 4.5, 4.1 to 3.7, and 3.3 to 3.0ka. These flood periods coincide with low soil formation signals. On the other hand, periods of increased alluvial soil formation from 6.8 to 6.6, 5.9 to 4.8, 4.5 to 4.1, 3.7 to 3.3, 3.0 to 2.8, and 1.8 to 1.6ka coincide with periods of low flood plain aggradation. The data reveal a coupling with North Atlantic cooling. Short-term periods of enhanced fluvial dynamics in Central Tunisia match well with North Atlantic cooling. The findings indicate a strong climatic link from 4.7ka until today. Compared to the Holocene floodplain dynamics in Tunisian drylands, the temperate mid-latitudes show Mid-Holocene switches in fluvial dynamics with opposite signs. Especially after 5ka North Atlantic driven flooding in the temperate Central European river systems contrast sharply to flood dynamics in arid to semiarid Mediterranean Tunisia. While under temperate climate conditions floodplain sedimentation decreases, it increases under more arid conditions. This may indicate that fluvial archives of dissimilar climatic zones reveal different threshold values and sedimentation patterns, and, therefore, different responses to climatic shifts. [Copyright &y& Elsevier]

Abstract: INTegration of Ice-core, MArine and TErrestrial records (INTIMATE) is a core project of the INQUA Palaeoclimate Commission, the primary goal of which is to synchronise records of the Last Glacial–Interglacial Transition (LGIT). Through a series of international workshops, INTIMATE has encouraged direct collaboration between scientists with interests and expertise in a wide range of palaeoenvironmental approaches. The workshops have focused on the dissemination of good practice in the dating, correlation and synthesis of diverse palaeoenvironmental records that span the LGIT. This special issue of Quaternary Science Reviews presents some of the outcomes of the 8th INTIMATE International Workshop held in Iceland in September 2005, and focuses on four themes considered vital to INTIMATE''s long-term strategy. (1) An event stratigraphy approach, which uses the Greenland oxygen isotope record as a stratotype sequence, lies at the core of INTIMATE''s operations. A revised event stratigraphy scheme for application to North Atlantic LGIT records is presented, which is based on the new GICC05 Greenland ice-core chronology. (2) New tree-ring data from Switzerland and the application of Bayesian-based procedures in the analysis of comprehensive radiocarbon data sets provide much potential for reducing the uncertainties in radiocarbon-based age models. (3) Three of the contributions present new evidence that helps to refine the tephrostratigraphy of the LGIT in the NE Atlantic and New Zealand regions. (4) Establishing the precise order and synchroneity of events during the LGIT is vital to understand the causes and effects of abrupt climate change. Data are presented from the Baltic region and Alaska, which vary in degree of compatibility with North Atlantic records. Two final papers consider the roles of Dansgaard–Oeschger events on thermokarst during the Middle Weichselian and of solar activity variations during the mid-Holocene; both illustrate how the INTIMATE event stratigraphy approach can apply to the study of other time intervals. [Copyright &y& Elsevier]

Quantitative reconstruction of the climatic history of the Chinese Loess Plateau is important for understanding present and past environment and climate changes in the Northern Hemisphere. Here, we reconstructed mean annual temperature (MAT) and mean annual precipitation (MAP) trends during the last 136ka based on the analysis of phytoliths from the Weinan loess section (34°24′N, 109°30′E) near the southern part of the Loess Plateau in northern China. The reconstructions have been carried out using a Chinese phytolith–climate calibration model based on weighted averaging partial least-squares regression. A series of cold and dry events, as indicated by the reconstructed MAT and MAP, are documented in the loess during the last glacial periods, which can be temporally correlated with the North Atlantic Heinrich events. Our MAT and MAP estimations show that the coldest and/or driest period occurred at the upper part of L2 unit (Late MIS 6), where MAT dropped to ca 4.4°C and MAP to ca 100mm. Two other prominent cold-dry periods occurred at lower Ll-5 (ca 77–62ka) and L1-1 (ca 23–10.5ka) where the MAT and MAP decreased to about 6.1–6.5°C and 150–370mm, respectively, ca 6.6–6.2°C and 400–200mm lower than today. However, the highest MAT (average 14.6°C, max. 18.1°C) and MAP (average 757mm, max. 1000mm) occurred at Sl interval (MIS 5). During the interstadial of L1-4–L1-2 (MIS 3) and during the Holocene warm-wet period, the MAT was about 1–2°C and MAP 100–150mm higher than today in the Weinan region. The well-dated MAT and MAP reconstructions from the Chinese Loess Plateau presented in this paper are the first quantitatively reconstructed proxy record of climatic changes at the glacial–interglacial timescale that is based on phytolith data. This study also reveals a causal link between climatic instability in the Atlantic Ocean and climate variability in the Chinese Loess Plateau. [Copyright &y& Elsevier]

This paper presents fossil beetle data from a Last Glacial Maximum site at the Lyndon Stream, in the Canterbury foothills, South Island, New Zealand. Paleotemperatures are derived using the maximum likelihood envelope (MLE) model developed for regions where modern distribution data are incomplete [Marra et al., 2004. Late quaternary climate change in the Awatere Valley, South Island, New Zealand using a sine model with a maximum likelihood envelope on fossil beetle data. Quaternary Science Reviews 23, 1637–1650]. The MLE model results indicate that summer temperatures in the Canterbury foothills, in close proximity to the major Rakaia glacier, at ca 22,000 14C yr BP were between 0.5°C warmer and 1.9°C cooler than present day in February (summer). Mean minimum winter temperatures ranged between 1°C warmer and 2.2°C cooler than the present day. These apparently surprising results confirm and quantify existing climate reconstructions from plant macrofossils from this site [Soons, J.M., Burrows, C.J., 1978. Dates for Otiran deposits, including plant microfossils and macrofossils, from Rakaia Valley. New Zealand Journal of Geology and Geophysics 21, 607–615]. They are consistent with new evidence of relatively mild conditions at least during some periods within the Last Glacial Maximum chron in New Zealand. [Copyright &y& Elsevier]

Abstract: Climatic change has often been cited as a determining factor in cultural changes in the context of the Harappan Civilisation of northwestern South Asia, 2500–1900BC. While these claims have been critiqued by archaeologists they continue to be accepted by non-archaeologists, including Quaternary scientists. The purpose of this paper is to assess the available evidence and published arguments and to provide a constructive working synthesis of evidence for the palaeoenvironmental setting of northwestern South Asia for the mid- to late Holocene, especially ca 4000–1000calBC, and its possible connection to important cultural changes. We conclude that Harappan urbanism emerged on the face of a prolonged trend towards declining rainfall. No climatic event can be blamed for a precipitous end of this civilisation, although strategic local shifts in agriculture that may have begun in response to prolonged droughts at ca 2200BC may have contributed to the de-urbanisation process and the restructuring of human communities over the following 200–300yr. [Copyright &y& Elsevier]

Peatland surface wetness records provide long Holocene palaeoclimate reconstructions at 101–102 year resolution. They reflect changes in water balance but the relative strength of precipitation and temperature signals are not known. In common with other non-annually resolved records, there has been no testing of the reconstructions against instrumental climate data. In this paper high-resolution records of palaeohydrological change reconstructed from testate amoebae analysis are used to examine critically the relationships between reconstructed water table change, instrumental water table and climate data. A 200-year record of reconstructed water table from northern England shows that the strongest control on reconstructed mean annual water table change is summer precipitation, with summer temperature becoming more important over longer time periods. A 50-year record from Estonia shows that both measured and reconstructed water table records are strongly correlated with summer precipitation. Summer temperature is also correlated with reconstructed water table. We conclude that peatland surface wetness records should be interpreted as primarily reflecting summer precipitation variability, with summer temperature increasingly important in more continental settings. [Copyright &y& Elsevier]