The Warm Winter Paradox in the Pliocene High Latitudes

Reconciling palaeodata with model simulations of the Pliocene climate is essential for understanding a world with atmospheric CO2 concentration near 400 parts per million by volume. Both models and data indicate an amplified warming of the high latitudes during the Pliocene, however terrestrial data suggests Pliocene high latitude temperatures were much higher than can be simulated by models. Here we show that understanding the Pliocene high latitude terrestrial temperatures is particularly difficult for the coldest months, where the temperatures obtained from models and different proxies can vary by more than 20 °C. We refer to this mismatch as the ‘warm winter paradox’. Analysis suggests the warm winter paradox could be due to a number of factors including: model structural uncertainty, proxy data not being strongly constrained by winter temperatures, uncertainties on data reconstruction methods and also that the Pliocene high latitude climate does not have a modern analogue. Refinements to model boundary conditions or proxy dating are unlikely to contribute significantly to the resolution of the warm winter paradox. For the Pliocene, high latitude, terrestrial, summer temperatures, models and different proxies are in good agreement. Those factors which cause uncertainty on winter temperatures are shown to be much less important for the summer. Until some of the uncertainties on winter, high latitude, Pliocene temperatures can be reduced, we suggest a data-model comparison should focus on the summer. This is expected to give more meaningful and accurate results than a data-model comparison which focuses on the annual mean.

Tree line shifts, changing vegetation assemblages and permafrost dynamics on Galdhøpiggen (Jotunheimen, Norway) over the past ~4400 years

An environmental reconstruction based on palynological evidence preserved in peat was carried out to examine late-Holocene alpine tree line dynamics in the context of past climatic changes on Galdhøpiggen (Jotunheimen, southern Norway). We analysed a peat core taken from a mire at the present-day tree line (1000 m a.s.l.), c. 450 m downslope from the lower limit of sporadic permafrost. We adopted a combination of commonly used indicators of species’ local presence to reconstruct past vegetation assemblages, such as the relative pollen abundance (%), pollen accumulation rate (PAR), and presence of indicator species. Additionally, fossil pollen from the peat sequence was compared to modern pollen from a surface moss polster to establish a modern analogue. The results were compared with studies covering the late-Holocene climatic changes in the area. The reconstruction demonstrates that a pine-dominated woodland reached above the present-day tree line at c. 4300 cal. yr BP, suggesting a warmer climate suitable for Scots pine ( Pinus sylvestris) growth at this altitude. Scots pine retreated to lower altitudes between c. 3400 and 1700 cal. yr BP, accompanied by the descent of the low-alpine shrub-dominated belt, in response to cooling climatic conditions. The colder period covered c. 1700–170 cal. yr BP, and an open downy birch ( Betula pubescens) woodland became widespread at 1000 m a.s.l., whilst pine remained sparse at this altitude. From c. 170 cal. yr BP onwards, warming allowed pine to re-establish its local presence alongside downy birch at 1000 m a.s.l.

sandbox – Creating and Analysing Synthetic Sediment Sections with R

The majority of palaeoenvironmental information is inferred from proxy data contained in accretionary sediments, called geo-archives. The validity of proxy data and analysis workflows are usually assumed implicitly, with systematic tests and uncertainty estimates restricted to modern analogue studies or reduced-complexity case studies. However, a more generic and consistent approach to exploring the validity and variability of proxy functions would be to translate a given geo-archive into a model scenario: a "virtual twin". Here, we introduce a conceptual framework and numerical toolset that allows the definition and analysis of synthetic sediment sections. The R package sandbox describes arbitrary stratigraphically consistent deposits by depth-dependent rules and grain-specific parameters, allowing full scalability and flexibility. Virtual samples can be taken, resulting in discrete grain-mixtures with well-defined parameters. These samples can then be virtually prepared and analysed, for example to test hypotheses. We illustrate the concept of sandbox, explain how a sediment section can be mapped into the model and, by focusing on an exemplary field of application, we explore universal geochronological research questions related to the effects of sample geometry and grain-size specific age inheritance. We summarise further application scenarios of the model framework, relevant for but not restricted to the broader geochronological community.

Planktic Foraminifera-Based Sea Surface Temperature Estimates and Late Quaternary Oceanography off New Zealand's West Coast

<p>Planktic foraminiferal assemblages were used to investigate the paleoceanography of the Eastern Tasman Sea over the last 480 kyrs (Marine Isotope Stages 12-1). One hundred and sixty-two faunas (96 picked and identified as part of this project (MIS 12-6) added to 66 census counts from Dr. M. Crundwell (MIS 6-1)) have been assembled from Marion Dufresne piston core MD06-2986 (~43˚ S. off New Zealand‟s west coast, 1477 m water depth). Faunal changes through the last five glacial-interglacial cycles are used to track surface water mass movement. Glacial periods are dominated by the eutrophic species Globigerina bulloides, with significant contributions from the temperate species Globoconella inflata. Temperate species Neogloboquadrina incompta and Gc. inflata dominate interglacials, with the former dominating the warmer parts and the latter dominating the cooler parts of the interglacials. Modern Analogue Technique (MAT) and an Artificial Neural Network (ANN) were used to estimate past sea surface temperatures (SST) based on the foraminiferal census counts data (23 species, ~46,000 specimens). SSTs show that MIS 12 was the longest, sustained cold period, while the coldest temperature was recorded in MIS 5d (~8º C). Interglacials MIS 11 and 5e are the two warmest stages of the record, with SSTs reaching ~18.5º C, about ~2º C warmer than present day. We find that contrary to either the western Tasman Sea or offshore eastern New Zealand, the eastern Tasman Sea has been fairly isolated from any major influx of subpolar or subtropical species carried in with surface water from either high or low latitude sources. Subtropical taxa abundance (Globigerinoides ruber, Neogloboquadrina dutertrei (D), Globigerinoides sacculifer, Globigerinella aequilateralis, Sphaeroidinellopsis dehiscens, Truncorotalia truncatulinoides (D), Beella digitata) is low (average ~0.6%) and only prominent during peak interglacials. Subantarctic taxa abundance (Neogloboquadrina pachyderma, Neogloboquadrina dutertrei (S)) is low (average ~5.1%), but significant, particularly in glacial periods. Comparison of faunal and SSTANN data along with ratios of Nq. pachyderma:Nq. incompta (previously referred to as coiling ratios of Nq. pachyderma) and absolute abundance of planktic productivity (a productivity proxy) suggest that the STF migrated northwards towards the site in all glacial periods, and may have moved over the site in MIS 12 and possibly MIS 5d. A latitudinal SSTANN 25 comparison between offshore eastern and western New Zealand reveals that MD06-2986 (~43º S) is most similar (~0.5º C) to ODP Site 1125 (~42º S). On the contrary, ODP Site 1119 (44º S) is ~5º C cooler than MD06-2986. This comparison highlights the significant changes in surface water masses off eastern New Zealand that exist in such a short span of latitude because of the influence of a complex submarine topography.</p>

Planktic Foraminifera-Based Sea Surface Temperature Estimates and Late Quaternary Oceanography off New Zealand's West Coast

<p>Planktic foraminiferal assemblages were used to investigate the paleoceanography of the Eastern Tasman Sea over the last 480 kyrs (Marine Isotope Stages 12-1). One hundred and sixty-two faunas (96 picked and identified as part of this project (MIS 12-6) added to 66 census counts from Dr. M. Crundwell (MIS 6-1)) have been assembled from Marion Dufresne piston core MD06-2986 (~43˚ S. off New Zealand‟s west coast, 1477 m water depth). Faunal changes through the last five glacial-interglacial cycles are used to track surface water mass movement. Glacial periods are dominated by the eutrophic species Globigerina bulloides, with significant contributions from the temperate species Globoconella inflata. Temperate species Neogloboquadrina incompta and Gc. inflata dominate interglacials, with the former dominating the warmer parts and the latter dominating the cooler parts of the interglacials. Modern Analogue Technique (MAT) and an Artificial Neural Network (ANN) were used to estimate past sea surface temperatures (SST) based on the foraminiferal census counts data (23 species, ~46,000 specimens). SSTs show that MIS 12 was the longest, sustained cold period, while the coldest temperature was recorded in MIS 5d (~8º C). Interglacials MIS 11 and 5e are the two warmest stages of the record, with SSTs reaching ~18.5º C, about ~2º C warmer than present day. We find that contrary to either the western Tasman Sea or offshore eastern New Zealand, the eastern Tasman Sea has been fairly isolated from any major influx of subpolar or subtropical species carried in with surface water from either high or low latitude sources. Subtropical taxa abundance (Globigerinoides ruber, Neogloboquadrina dutertrei (D), Globigerinoides sacculifer, Globigerinella aequilateralis, Sphaeroidinellopsis dehiscens, Truncorotalia truncatulinoides (D), Beella digitata) is low (average ~0.6%) and only prominent during peak interglacials. Subantarctic taxa abundance (Neogloboquadrina pachyderma, Neogloboquadrina dutertrei (S)) is low (average ~5.1%), but significant, particularly in glacial periods. Comparison of faunal and SSTANN data along with ratios of Nq. pachyderma:Nq. incompta (previously referred to as coiling ratios of Nq. pachyderma) and absolute abundance of planktic productivity (a productivity proxy) suggest that the STF migrated northwards towards the site in all glacial periods, and may have moved over the site in MIS 12 and possibly MIS 5d. A latitudinal SSTANN 25 comparison between offshore eastern and western New Zealand reveals that MD06-2986 (~43º S) is most similar (~0.5º C) to ODP Site 1125 (~42º S). On the contrary, ODP Site 1119 (44º S) is ~5º C cooler than MD06-2986. This comparison highlights the significant changes in surface water masses off eastern New Zealand that exist in such a short span of latitude because of the influence of a complex submarine topography.</p>

Detection of Large Holocene Earthquakes in the Sedimentary Record of Wellington, New Zealand, Using Diatom Analysis

<p>New Zealand is situated on the boundary between the Pacific and Australian tectonic plates. The Wellington region lies near the southern end of the Hikurangi subduction zone and within a zone of major, active strike-slip faults. Wellington's paleoseismic and historic records indicate that large surface rupture earthquakes have occurred on these faults in the past. Development of a complete record of past large earthquakes is a high priority for the region because of the risk posed by occurrence of large earthquakes in the future. The existing paleoseismic record has been derived predominantly from studies of fault trench stratigraphy, raised beach ridges and offset river terraces. The sedimentary record of lakes and coastal waterbodies is a source of information that has not been used specifically for paleoseismic purposes in the region. Therefore investigation of Wellington's sedimentary record is used in this thesis to make a contribution to the paleoseismic record. Holocene sedimentary sequences are studied from three small, low elevation, coastal waterbodies: Taupo Swamp, Okupe Lagoon and Lake Kohangapiripiri. Sequences of between 200 and 650 cm depth were collected using a hand-operated coring device. Sedimentology and diatom microfossil content were analysed and interpreted to enable reconstruction of paleoenvironment at each site. Radiocarbon dating was used to provide chronologies for the sequences that are aged between 5000 and 7500 calibrated years before present (cal. years BP). Diatom analysis is the main tool used to reconstruct paleoenvironment and detect evidence for occurrence of past large earthquakes. To aid reconstruction of sedimentary sequences used in this project, as well as coastal sequences in New Zealand in general, a coastal diatom calibration set was constructed using 50 sites around New Zealand. Modern diatom distribution and abundance, and associated environmental variables are analysed using ordination and weighted averaging techniques. Detrended correspondence analysis arranges species according to salinity preferences and divides sites clearly into waterbody types along a coastal gradient. This analysis enables reconstruction of waterbody type from fossil samples by passive placement onto ordination diagrams. Weighted averaging regression of calibration set samples results in a high correlation (r2jack=0.84) between observed and diatom inferred salinity, and enables salinity preferences and tolerances to be derived for 100 species. This confirms for the first time that species' preferences derived in the Northern Hemisphere are generally applicable to diatoms living in the coastal zone of New Zealand. Weighted averaging calibration and the modern analogue technique are used to generate quantitative estimates of paleosalinity for fossil samples. Paleoenvironmental reconstructions of Taupo Swamp, Okupe Lagoon and Lake Kohangapiripiri indicate that each waterbody has been isolated from the sea during the late Holocene. Isolation has been achieved through interplay of sediment accumulation causing growth of barrier beaches, and coseismic uplift. Ten distinct transitions between different paleoenvironments are recognised from the three sequences. These transitions involve changes in relative sea level or water table level often in association with catchment disturbance or marine influx events. All transitions occur suddenly and are laterally extensive and synchronous within each waterbody. Quantitative estimates of paleosalinity and waterbody type are used to differentiate between large and small magnitude changes in paleoenvironment. Five transitions involve large amounts of paleoenvironmental change and provide evidence for earthquakes occurring at approximately 5200, approximately 3200, and approximately 2300 cal. years BP. Five other transitions are consistent with the effects of large earthquakes occurring at approximately 6800, 2200, approximately 1000, approximately 500 cal. years BP and 1855 AD but do not provide independent evidence of the events. Environmental transitions at Lake Kohangapiripiri clarify the timing of rupture of the Wairarapa Fault by bracketing incompatible age estimates derived from two different sites on the fault. The oldest environmental transitions recognised at Taupo Swamp and Okupe Lagoon both occur at approximately 3200 cal. years BP indicating that western Wellington was uplifted at this time. Environmental transitions are recorded at all three study sites at approximately 2300 cal. years BP indicating that the entire western and central Wellington region experienced coseismic uplift at this time. Because of the distance between sites this apparent synchroneity implies that several faults in the region ruptured at a similar time. Investigation of sedimentary sequences contributes to the existing paleoseismic record by providing additional estimates of timing for past large earthquakes, enabling estimation of the areal extent of the effects of past earthquakes, and by highlighting periods of fault rupture activity in the late Holocene.</p>

Detection of Large Holocene Earthquakes in the Sedimentary Record of Wellington, New Zealand, Using Diatom Analysis

<p>New Zealand is situated on the boundary between the Pacific and Australian tectonic plates. The Wellington region lies near the southern end of the Hikurangi subduction zone and within a zone of major, active strike-slip faults. Wellington's paleoseismic and historic records indicate that large surface rupture earthquakes have occurred on these faults in the past. Development of a complete record of past large earthquakes is a high priority for the region because of the risk posed by occurrence of large earthquakes in the future. The existing paleoseismic record has been derived predominantly from studies of fault trench stratigraphy, raised beach ridges and offset river terraces. The sedimentary record of lakes and coastal waterbodies is a source of information that has not been used specifically for paleoseismic purposes in the region. Therefore investigation of Wellington's sedimentary record is used in this thesis to make a contribution to the paleoseismic record. Holocene sedimentary sequences are studied from three small, low elevation, coastal waterbodies: Taupo Swamp, Okupe Lagoon and Lake Kohangapiripiri. Sequences of between 200 and 650 cm depth were collected using a hand-operated coring device. Sedimentology and diatom microfossil content were analysed and interpreted to enable reconstruction of paleoenvironment at each site. Radiocarbon dating was used to provide chronologies for the sequences that are aged between 5000 and 7500 calibrated years before present (cal. years BP). Diatom analysis is the main tool used to reconstruct paleoenvironment and detect evidence for occurrence of past large earthquakes. To aid reconstruction of sedimentary sequences used in this project, as well as coastal sequences in New Zealand in general, a coastal diatom calibration set was constructed using 50 sites around New Zealand. Modern diatom distribution and abundance, and associated environmental variables are analysed using ordination and weighted averaging techniques. Detrended correspondence analysis arranges species according to salinity preferences and divides sites clearly into waterbody types along a coastal gradient. This analysis enables reconstruction of waterbody type from fossil samples by passive placement onto ordination diagrams. Weighted averaging regression of calibration set samples results in a high correlation (r2jack=0.84) between observed and diatom inferred salinity, and enables salinity preferences and tolerances to be derived for 100 species. This confirms for the first time that species' preferences derived in the Northern Hemisphere are generally applicable to diatoms living in the coastal zone of New Zealand. Weighted averaging calibration and the modern analogue technique are used to generate quantitative estimates of paleosalinity for fossil samples. Paleoenvironmental reconstructions of Taupo Swamp, Okupe Lagoon and Lake Kohangapiripiri indicate that each waterbody has been isolated from the sea during the late Holocene. Isolation has been achieved through interplay of sediment accumulation causing growth of barrier beaches, and coseismic uplift. Ten distinct transitions between different paleoenvironments are recognised from the three sequences. These transitions involve changes in relative sea level or water table level often in association with catchment disturbance or marine influx events. All transitions occur suddenly and are laterally extensive and synchronous within each waterbody. Quantitative estimates of paleosalinity and waterbody type are used to differentiate between large and small magnitude changes in paleoenvironment. Five transitions involve large amounts of paleoenvironmental change and provide evidence for earthquakes occurring at approximately 5200, approximately 3200, and approximately 2300 cal. years BP. Five other transitions are consistent with the effects of large earthquakes occurring at approximately 6800, 2200, approximately 1000, approximately 500 cal. years BP and 1855 AD but do not provide independent evidence of the events. Environmental transitions at Lake Kohangapiripiri clarify the timing of rupture of the Wairarapa Fault by bracketing incompatible age estimates derived from two different sites on the fault. The oldest environmental transitions recognised at Taupo Swamp and Okupe Lagoon both occur at approximately 3200 cal. years BP indicating that western Wellington was uplifted at this time. Environmental transitions are recorded at all three study sites at approximately 2300 cal. years BP indicating that the entire western and central Wellington region experienced coseismic uplift at this time. Because of the distance between sites this apparent synchroneity implies that several faults in the region ruptured at a similar time. Investigation of sedimentary sequences contributes to the existing paleoseismic record by providing additional estimates of timing for past large earthquakes, enabling estimation of the areal extent of the effects of past earthquakes, and by highlighting periods of fault rupture activity in the late Holocene.</p>

Long-acting insulin analogue in the treatment of type 2 diabetes mellitus: emphasis on proven efficacy and safety

In time, prescription of insulin therapy (IT) becomes inevitable for many patients with type 2 diabetes mellitus (DM) to achieve and maintain the target hypoglycemic range.According to the current guidelines, the addition of basal insulin to glucose-lowering therapy in patients with insufficient control of type 2 diabetes, gradual titration of its dose in accordance with a fasting blood glucose level is an effective and safe method for initiating IT. The properties of modern long-acting insulin analogues are considered. Glargine 300 U/ml is a modern analogue of long-acting insulin that is intended to be used once a day. The glargine molecule forms the basis of the drug. Increasing the concentration of glargine per volume unit and formation of a smaller subcutaneous depot led to a change in the pharmacokinetic properties of the drug. Glargine 300 IU/ml provides a more stable, long-term, predictable action with low glycemic variability as compared with glargine 100 IU/ml, which reduces the risk of hypoglycemia. The sugar-reducing efficacy and safety of insulin glargine 300 U/ml as evidenced by the findings of the international clinical phase III EDITION studies are discussed. Insulin glargine 300 U/ml showed a similar decrease in HbA1c levels compared to insulin glargine 100 U/ml with an improved safety profile (lower risk of developing episodes of confirmed or severe hypoglycemia at all times of the day, including the nighttime) and a less pronounced effect on the body weight of patients with type 2 diabetes. The efficacy and safety of the use of glargine 300 U/ml has been confirmed in type 2 diabetes patients with chronic kidney disease and the elderly. In the BRIGHT study, glargine 300 U/ml showed comparable glycemic control when it is being compared.