Speleothems are considered a reliable proxy for paleoclimatic reconstructions and analysis of stable carbon isotopes in speleothems is used for paleoclimatic reconstructions. However, in temperate areas that lacks C4 vegetation there are uncertainties in how to interpret changes in the δ13C signal. The aim of this study is toincrease the understanding of how the δ13C signal in speleothems from temperateareas can be interpreted. The study was divided in two parts, first a literature studythat focused on interpretations of the δ13C signal in speleothems from temperate areasand a case study in which a comparison of seven 13C records from similarenvironments in the Scandes Mountains and the Alps are made. The results from the literature study were used in the case study to draw conclusions on tree line and vegetation changes during Holocene in central northern Scandinavia. The study showed that trends in interpretation of the δ13C signal in speleothems from temperateareas are that low δ13C values are interpreted as wetter, warmer conditions with higherbio productivity, and high δ13C values are interpreted as colder, drier conditions withlower bio productivity. Further it was found in the study that vegetation changes seen in Holocene pollen data are also seen in δ13C records from Scandinavia. The δ13Csignal in temperate speleothems therefore appears to be related to changes invegetation density and to tree-line changes.

Here, we provide results of mid/late Holocene fresh water Ostracoda analyses from coastal modern lake basins in the Thrace region of Istanbul and Sarikum Lake, on the Black Sea coast near Sinop. While neither diatoms nor Cladocera are abundant in the sediments, Podocopian (fresh water) ostracods preserved well, but with discontinuous occurences during the mid/late Holocene. Un-noded forms of Cyprideis torosa, along with other Podocopian ostracods, dominated the sediments of all three lakes. Studying these three lagoonal basins along the Black Sea and Thracian coasts of Turkey allows reconstruction of long term, regional environmental histories, using the following methods. Loss-on-ignition (LOI) analyses at 1 cm intervals of short and long cores provide stratigraphic cross-correlation and calculations of organic matter, carbonate and mineral weight. At 5 cm intervals, spectrally-inferred chlorophyll-a contents by visible reflectance spectroscopy (Michelutti et al., 2010), provide estimates of algal production. Trace element analysis (Mg/Ca and Sr/Ca) using ICP-AES (coupled plasma atomic emission spectroscopy) is applied to fully calcified adult specimens of un-noded forms of Cyprideis torosa shells (which dominate the uppermost 145 cm of Terkos Lake). 210Pb and 137Cs dating of short cores, and AMS 14C dating of long cores, are used to infer sediment accumulation rates and to place specific ages on inferred environmental changes. Benthic foraminifers, gastropods, bivalves, single valves of fossil Glochidia, and Charophyte seeds are the other biological indicators observed within the sediment archive. Based on these data: 1. Terkos Lake sediments contain records of multiple, sub-millennial scale marine incursion events, over the last 2.8 ka, inferred to be the result of severe storms or tsunami on the Black Sea, including the tsunami in AD 1598 and AD 557-543 / 2. short core sediments from Sarikum Lake reveal sharp decreases in organic matter, carbonate, and increases in algal production and sand amount that suggest a storm or more recent earthquake / such as the Great Erzincan Earthquake (26 December, 1939) or the Bartin earthquake (3 September, 1968) while four more such events appear in the undated sediments of the Sarikum Lake long core / and 3. a large earthquake in AD 447 that affected the entire Sea of Marmara (Leroy et al., 2002) does not appear in the B&uuml / y&uuml / k&ccedil / ekmece Lake sediment record, but there is evidence for a significant hiatus in these deposits before the development of the dam (AD 1989) and after the youngest AMS date (2400 cal yrs BP). This suggests that B&uuml / y&uuml / k&ccedil / ekmece Lagoon was an environment of net erosion prior to its artificial impoundment, either from gradual processes or from scouring by one or more tsunami.

Stable isotopes in ice cores drilled in the polar and high-mountain region have been used intensively to reconstruct past climatic changes and atmospheric dynamics. However, no similar studies have been conducted on perennial ice accumulations in caves due to a limited understanding of the links between the external and cave environments, and the way in which the climatic signal can be recorded by the cave ice. In this thesis, we successfully designed and build a research methodology for the reconstruction of past climatic changes based on perennial ice accumulation in caves, using as example the Scarisoara Ice Cave, Romania. The ice block in this cave preserves a large variety of candidate proxies for both past climate and environmental changes, the most significant ones being the stable isotopic composition of the ice (a proxy for air temperature) and pollen remains. The ice block has formed by the successive accumulation of layers formed by the freezing of water accumulated from late summer through mid-autumn precipitation. An original method has been developed for the reconstruction of the stable isotopic composition of water before freezing, and further, of the late summer air temperature. Pollen in the ice has been found to reflect changes in surface vegetation at both local and regional scale. A 22 m long ice core has been extracted from the ice block, and stable isotope analyses were performed at high resolution on its entire length. Twenty-sex radiocarbon ages have been used to derive a precise depth-age model for this core. The stable isotope data covers almost the entire Holocene, between 0.09 and 9.75 ka BP. The first order fluctuation broadly follows the orbitally induced Northern Hemisphere September insolation, with a minimum in the early Holocene, a slow climb towards a maximum at ~5.0 ka, followed by a very slow cooling towards the present, accentuated after ~0.5 ka. Superimposed on the long-term variations a series of rapid cooling events (RCE) are recorde, the most notable ones being at 9.5 ka, 8.2 ka, 7.9 ka, 6 ka, 4.2 ka, 3.2 ka and 0.9 ka. The timing of these RCEs agrees remarkably well with the Holocene rapid climatic changes and the ice rafted debris (IRD) events in the North Atlantic (NA). Our data suggests that the general trends of temperature changes in mainland Europe during the Holocene were governed by changes in solar output. RCEs were synchronous with NA IRD events, the NA climatic signal originating from sea surface temperature changes and being amplified by atmospheric dynamics. The stable isotope data spanning the past 2000 years clearly shows four climatic events over this interval, attributed to the Roman Warm period (RWP), the Dark Ages Cold Period (DACP), Medieval Warm Period (MWP) and the Little Ice Age (LIA). Our data suggests that air temperature was highly variable during the LIA and more stable during the warm MWP and RWP. As ice caves were described in many parts of the world otherwise poorly represented in ice-based paleoclimatology, the results of this study could open a new direction in paleoclimatic research, so that an array of significant paleoclimate data can be developed based on their study.

This thesis investigates the past extent, structure and dynamics of Mar Lodge Caledonian pine (Pinus sylvestris L.) woodland, near Braemar in the south-eastern Cairngorms. The geographical extent and Holocene history of the Scottish pinewoods are generally understood, but the Mar pinewoods are relatively obscure. This thesis is concerned with the Holocene history of the Mar pinewoods; the timing and reasons for first appearance, the increase in abundance of Pinus to become a dominant species, the spatial extent of the woodland and its structure and form. The investigation includes changes to the woodland assemblage during its fragmentation and disappearance in the late Holocene and possible influences on the woodland from people living in the area. At the heart of this thesis is an understanding of the factors underpinning the ecology of Pinus and the response of the species to competition with other taxa. This is related to the spatial and temporal changes in climate that contribute to the location and development of Pinus in Scotland and Mar Lodge. Areas comparable to Mar Lodge are defined as ‘core areas’ of pine woodland rather than ‘native areas’. This avoids the necessity of considering every short period of colonisation by Pinus in areas distal to large populations. The location, extent, form and behaviour of woodland according to macro sub-fossils and micro sub-fossils is used to define core woodland as those with a long presence of Pinus, often continuing to the present day. Areas with a long history but no extant population are regarded as peripheral areas. This thesis consists of extensive palaeoecological investigations of three peat sequences: from within extant pine woodland (Doire Bhraghad), from just beyond its edge (White Bridge) and from peat with sub-fossil pine stumps located 10km west of the modern range of Pinus (Geldie Lodge). A range of techniques, including loss of mass on ignition and colorimetric light transmission analysis are applied to the peat, but palynological techniques form the basis of the investigation. Stomatal counts are used in conjunction with pollen counts to explore the process of Pinus colonisation, and its increase in abundance to form woodland. Pinus percentage and influx, together with the ratio of arboreal to non-arboreal pollen and the percentage of Empetrum are used to define the density of the woodland canopy. The stability of the Doire Bhraghad assemblage confirms the area as core Pinus woodland. Pinus is present from c. 9600 cal BP and dominates woodland from c. 9150 cal BP. Woodland here is a closed, solely Pinus canopy from c. 8600 until 4000 cal BP. Arrival of Pinus at Geldie Lodge is undated but occurs before c. 7550 cal BP. Woodland is always more open; Pinus is co-dominant with Betula, showing affinity with other peripheral areas. Pinus woodland fragments at all Mar Lodge sites from c. 3900 cal BP, disappearing from Geldie Lodge by c. 2800 cal BP and White Bridge by c. 1900 cal BP. Calluna replaces Pinus as the dominant species at all three sites. The disappearance of Pinus is thought to relate to regional climatic change toward wetter conditions. At Geldie Lodge a prior Coleopteran study suggests Pinus growing on the mire surface to be small and short lived. These may not have been the only trees growing in the area but they perhaps contributed to the major fluctuations in arboreal and non-arboreal pollen. Early canopy fluctuations (c. 7550 to 6000 cal BP) at Geldie Lodge may be related to Mesolithic human activity; there is stronger evidence of human presence from c. 4000 cal BP, possibly including cereal cultivation. Evidence from Doire Bhraghad and White Bridge is indicative only of low intensity grazing activity. It is unlikely that human activity instigated the fragmentation and disappearance of woodland, but may have contributed to the process.

Rapid tropical glacier retreat over the last 50 years has been well documented, and has received significant media attention. Many studies suggest these changes are due to rising global surface air temperatures, however disentangling the effects of temperature and precipitation has hampered scientific consensus. Furthermore, because of the shortness of the instrumental record, it is difficult to assess the larger significance of the climate changes associated with the decline of tropical glaciers. Here, we present a locally calibrated, independent temperature reconstruction for the past 1,500 years from Laguna Chingaza, Colombia based on distributions of branched Glycerol Dialkyl Glycerol Tetraethers (brGDGTs) in order to assess the controls on long term temperature variability in the tropical Andes, and their relationship with growth and demise of Andean glaciers. Comparison of reconstructed temperatures with the instrumental record suggests that our proxy record faithfully records decadal to century scale trends in temperature. The largest temperature decline over the last 1,500 years was a decrease of 2.5 ± 0.3 °C during the Little Ice Age (LIA), reaching lowest temperatures during the mid-17th century, and is broadly consistent with terrestrial temperature reconstructions throughout the tropics and the higher latitudes. The structure and timing of temperature changes at Laguna Chingaza are remarkably similar to recent terrestrial temperature reconstructions from elsewhere in the tropics, including sites in the tropical Pacific and equatorial Africa, suggesting that these changes are widespread in the tropics. Together, these records suggest that warming over the last few decades is unprecedented over the last 1,500 years, including the Medieval Climate Anomaly (800-1150 AD). Comparison of these temperature changes with records of Andean glacier limits suggests that temperature is the dominant driver of glacial retreat, particularly over the past few decades. Additionally, paleotemperatures inferred from LIA and recent glacial equilibrium line altitudes (ELAs) underestimate past changes in temperature when compared with brGDGTs reconstructions, suggesting that changes in precipitation complicate the use of glacier ELAs to reconstruct past temperatures. The coupling of temperature and ice extent in South America suggests that with projected future warming, the health of tropical glaciers could be in jeopardy, significantly impacting the communities and ecosystems that depend on them. / text

A study of marine palaeo-landscape development through a sediment core in the western Hong Kong waters has been carried out in this project as the sedimentation record could reflect the environmental changes during the Holocene period. The objectives of this study was to reveal the influences of Holocene post-glacial sea-level fluctuations and the monsoonal freshwater discharge changes to the sedimentation processes in the mouth region of the Pearl River Estuary. These are the two important factors which shape the palaeo-landscape development. Data has been obtained from a ground-truthing vibrocore to 35m below the seafloor at the south of the Shek Pik Reservoir, south Lantau Island. The sediment core was subsampled for elemental analysis to study the sources of the organic carbon by use of stable carbon isotope ratio (Ϭ13C) and for particle size analysis to reveal the energy state of the sedimentary environment. Shell fragments were chosen for radiocarbon analysis to construct the core chronology and marine seismic profiles were obtained to present the sub-bottom geological layers. The data is presented in the form of graphs and tables in showing the sediment changes along the core in different period of time. The data has been interpreted in relation to the knowledge of post-glacial sea-level rise and the proposed model of the Pearl River Estuary evolution from previous studies. Comparison is also made with other sediment cores around the Lantau Island to reveal the regional palaeo-environmental changes in the Holocene period. It is concluded that the sediment core has revealed four major phases of environmental change which is in general agreement with the previous studies except this data set has also shown a few localized climatic events in the mid-Holocene period. The sea-level low stand in the late Pleistocene had incised a network of drainage system on the exposed continental shelf which is the north South China Sea in present time. The rapid rising sea-level by Melt Water Pulse 1B filled the palaeo-valleys with alluvium deposits from 10600 to 9000 cal. yr BP at high sedimentation rate and the East Asian Monsoon was strengthened from 8800 to 5500 cal. yr BP as shown by the freshwater organic carbon deposited in the marine environment. Unconfined deposition occurred when the sediments spilled out of the palaeo-valleys and slowly covered the basin in stable sea-level and low hydrodynamic conditions. / published_or_final_version / Applied Geosciences / Master / Master of Science

A continuous, decadal-scale resolution multi-proxy record of climate variability over the past 1400 years in the northern Gulf of Mexico (GOM) was constructed from a box core recovered in the Pigmy Basin. Proxies include paired analyses of Mg/Ca and oxygen isotopes in the white variety of the planktic foraminifer Globigerinoides ruber and relative abundance variations of G. sacculifer in the foraminifer assemblages. Two multi-decadal intervals of sustained high Mg/Ca values indicate GOM sea-surface temperatures (SSTs) were as warm or warmer than near-modern conditions between 1000 and 1400 yrs BP. Foraminiferal Mg/Ca values during the coolest interval of the Little Ice Age (ca. 250 yrs BP) indicate that SST was 2 - 2.5 degrees Celcius below modern SST. Four minima in the Mg/Ca record between 900 and 250 yrs BP correspond with the Maunder, Spörer, Wolf and Oort sunspot minima, suggesting a link between solar insolation and SST variability in the GOM. An abrupt shift recorded in both the oxygen isotopic ratio of calcite and relative abundance of G. sacculifer occurs ~600 yrs BP. The shift in the Pigmy Basin record corresponds with a shift in the sea-salt-sodium (ssNa) record from the GISP2 ice core, linking changes in high-latitude atmospheric circulation with the subtropical Atlantic Ocean.

This thesis builds on the work of previous coleopteran-based climatic reconstructions to recreate the environment and climate of the last 20,000 14C years of northwest Europe using the data and methods available within the Bugs Coleopteran Ecology Package, and aims to assess the ability of the BugsCEP results to provide information regarding events and anthropogenic changes on environment during the Anthropocene. Samples and data from 134 sites across northwest Europe and the British Isles were included in this study. The Mutual Climatic Range method and the BugStats module based on habitat code classifications were used to create the climatic and environmental reconstructions respectively, the results of which are provided in eight isotherm maps for 14.5-9 14C years BP and 2 EcoFigure graphs for 20,000 14C to present. While the results of some isotherm maps align with the changes described in previous studies, other climate trends are muted within these results. Likewise, some previously recognized environmental shifts in Europe are visible, whereas other major events are not distinguishable within the environmental record. An assessment of the environmental reconstruction results finds that though there is not sufficient material to support any proposed Anthropocene start dates, effects of anthropogenic influence upon the environment may be visible starting within the last 2,000 14C years; the results also show some support for the Vera Hypothesis.

This dissertation project focuses on three study areas in the middle Tanana Valley (mTV) to provide records of local terrestrial ecological contexts and environmental changes in lowland settings that dated to the Late Glacial and early Holocene (16,000 to 6,000 cal. years ago) in interior Alaska and Eastern Beringia. The archaeological record of the mTV provides a rich history of hunter-gatherer land use dating over 14,000 years old. This project is part of two larger projects focused on prehistoric human ecology and foraging behavior in Eastern Beringia: the Quartz Lake-Shaw Creek Flats Multidisciplinary and Upward Sun River Site Projects. The study areas are spread out across a 4,000 km2 area in the mTV and contain the presence of archaeological sites that have records of well-developed stratification of sediments and soils and preserved macrofossils. Two of the study areas are dune fields: the Little Delta Dunes (including the Upward Sun River Site) and Rosa-Keystone Dunes Fields; the third area is Quartz Lake, one of the largest lakes within the region. As a whole they provide important information to understand the evolution of regional landscapes, paleoecological systems, and paleoenvironmental conditions dating back to 25,000 years ago, over 10,000 years prior to the currently accepted earliest human occupation of the region. Late Glacial and early Holocene landscapes of the mTV were ones of moderate stability and landscape disturbance with high rates of loess and aeolian sand deposition, and the presence of early-to-middle successional vegetation communities (herbs and forbs, shrubs, and deciduous trees) that fostered the presence of diverse mammalian faunal communities that no longer coexist in the region. As the middle Holocene approached, landscapes became increasingly stable with the expansion of the boreal forest and aeolian deposition drastically decreased throughout the mTV. The disturbances that fostered the highly productive early-to-middle successional vegetative communities in the Late Glacial and early Holocene became progressively partitioned in the middle Holocene and primarily relegated to active floodplains. These local ecological contexts can be used to assess changes in Late Glacial and Holocene faunal diversity and in human ecology and foraging behavior in interior Alaska and Eastern Beringia.

A multi-proxy approach was used to generate a continuous, sensitive Holocene palaeoclimatic record for Glen Affric, north west Scotland. Fluctuations in lake-level were used as a proxy for shifts in precipitation. Rigorous site selection criteria and a new methodology were developed to interpret the lacustrine sediment record in terms of climatically driven changes in water depth by separating (a) allogenic from autogenic sediment inputs and (b) explicitly linking the marginal fen peat system responded to changes in lake-level. The sedimentary record from the lake site, Loch Coulavie, suggests that lake-level has fluctuated repeatedly throughout the Holocene. The comparative magnitude of changes in lake-level defined the relative intensity of shifts in precipitation. Variations in mire surface wetness, as determined through humification analysis, from a series of four hydrologically isolated ombrotrophic blanket mire sites through the east-west trending glen, were used to generate a record of changes in effective precipitation. A reliable radiocarbon chronology obtained from both proxy records allowed the synthesis of these data sets and the definition of Holocene climate change in terms of relative shifts in temperature and precipitation. The data suggests that the early Holocene was more stable in terms of both temperature and precipitation, but that after c. 6200 BP (7200 cal. BP) both temperature and precipitation became highly variable. Several short-lived, abrupt high intensity shifts to increased precipitation occur at c. 6200 BP (7200 cal. BP), c. 5000 BP (5700 cal. BP), c. 3000 BP (3200 cal. BP) and c. 2400 BP (2350 cal. BP). Holocene climatic variability within Glen Affric corresponds to records of changes in North Atlantic oceanic circulation patterns. The predominance of atmospheric systems, such as Atlantic westerlies, may also have controlled spatial climatic variability within the glen, with the periodic establishment of very steep west-east climatic gradients, steeper than at the present day.