427 research outputs found
Multi-proxy Holocene palaeoclimate records from Walton Moss, northern England and Dosenmoor, northern Germany, assessed using three statistical approaches
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Oxygen-isotope variability across the 8.2 ka cold event in an ombrotrophic peat bog on the Bonavista Peninsula, Newfoundland
No full textThe 8.2 ka BP event in north eastern North America: first combined oxygen and hydrogen isotopic data from peat in Newfoundland.
No full textFinding direct evidence for atmospheric circulation change in terrestrial records of Holocene climate variability remains a fundamental challenge. Here we present the first combined stable oxygen and hydrogen isotopic palaeorecord from a peatland core in Newfoundland, Canada. Sphagnum cellulose samples were isolated from a core from Nordan's Pond Bog, Newfoundland, and analysed for ?D values. Combined with existing ?18O data, the resulting ?D/?18O bi-plot correlates directly with existing measurements of the modern (late 20th century) isotopic composition of precipitation from GNIP stations in Nova Scotia and Labrador, implying a close relationship between the estimated isotopic composition of source water used by the mosses and that of the source precipitation. We use the relative variations between the two isotope records to test the hypothesis that atmospheric circulation changed in the millennium following the 8.2-ka BP climate event. The data reveal a secondary complex isotopic response ?200 years (8250–8050 a BP) after a primary oxygen isotopic event that is widespread in the north Atlantic region. This secondary event is characterized by a divergence in oxygen and hydrogen isotope records that can most plausibly be explained by the augmentation of precipitation moisture from a more distant and more continental vapour source
Evidence of the severity of the 8.2ka cold event from an ombrotrophic peat bog in Newfoundland
No full textSaint Augustine's Critical Judgment of the Pagan Writers
No full textThe following is an attempt to study Saint Augustine’s attitude toward the Greek and Latin pagan writers. An effort has been made to record all of the direct quotations of the pagan authors used by Saint Augustine in the twenty-two books of his Be Civitate Dei. |I have undertaken to emphasize the fact that the number of times an author has been quoted and the manner in which each author has been described somewhat emphasizes Augustine’s judgment of them. |Therefore, with the chart containing the above mentioned information, I have included short commentaries and recordings of those quotations to indicate Augustine’s appraisal of those who were responsible for them.ProQuest Traditional Publishing Optio
Reclaiming Our Democracy: Challenging Global Poverty and Climate Change through Civic Action
No full textThe Center for Global Education\u27s Global Topics Series Fall 2013 Lecture was delivered by Sam Daley-Harris, global activist, author and microfinance trailblazer. His work on the international Microcredit Summit Campaign has brought global microloans to over 100 million impoverished families, and has helped bring issues of climate change into the national spotlight. A close collaborator of Nobel Prize Laureate Muhammad Yunus and recent TED Talks presenter, Daley-Harris has pioneered a brand of activism that inspires ordinary citizen to effectively engage the political and media establishements in order to make their voices and causes heard -- and heeded
Holocene climate variability revealed by oxygen isotope analysis of Sphagnum cellulose from Walton Moss, northern England
No full textStable isotope analyses of Sphagnum alpha-cellulose, precipitation and bog water from three sites across northwestern Europe (Raheenmore, Ireland, Walton Moss, northern England and Dosenmoor, northern Germany) over a total period of 26 months were used to investigate the nature of the climatic signal recorded by Sphagnum moss. The ?18O values of modern alpha-cellulose tracked precipitation more closely than bog water, with a mean isotopic fractionation factor ?cellulose-precipitation of 1.0274 ± 0.001 (1?) (?27‰). Sub-samples of isolated Sphagnum alpha-cellulose were subsequently analysed from core WLM22, Walton Moss, northern England yielding a Sphagnum-specific isotope record spanning the last 4300 years. The palaeo-record, calibrated using the modern data, provides evidence for large amplitude variations in the estimated oxygen isotope composition of precipitation during the mid- to late Holocene. Estimates of palaeotemperature change derived from statistical relationships between modern surface air temperatures and ?18Oprecipitation values for the British Isles give unrealistically large variation in comparison to proxies from other archives. We conclude that use of such relationships to calibrate mid-latitude palaeo-data must be undertaken with caution. The ?18O record from Sphagnum cellulose was highly correlated with a palaeoecologically-derived index of bog surface wetness (BSW), suggesting a common climatic driver.<br/
Terrestrial climate signal of the "8200-yr cold event" in the Labrador Sea region
No full textAccelerated melting of Greenland ice has raised concern about the future impact of enhanced freshwater discharge on regional climate through its effect on ocean circulation. An abrupt cooling event ca. 8200 cal. yr B.P. has been linked to meltwater from the decaying North American ice sheet. Oxygen isotopic analyses of cellulose from subfossil Sphagnum mosses, isolated from a Newfoundland peat core, reveal a pronounced anomaly ca. 8350 yr B.P. with a duration of ~150 years. The maximum estimated ?18Oprecipitation change, 4.53‰ ± 1.05‰ (Vienna Standard Mean Ocean Water), is the largest observed in the circum-North Atlantic region. The magnitude of change exceeds that predicted by recent paleoclimate simulations. Comparisons with recent records of surface and deep ocean proxies in the Labrador Sea and the wider North Atlantic region suggest synchroneity. However, an ~200 year delay between the responses of the Labrador Sea region and the Greenland Ice Sheet to the effects of meltwater release remains to be explained
The use of k-values to examine plant ‘species signals’ in a peat humification record from Newfoundland
No full textPeat humification analysis has been used widely over the last three decades to reconstruct bog surface wetness (BSW) for use as a palaeoclimate proxy. The technique has the advantage that it is quick and relatively inexpensive to perform, allowing for high resolution and contiguous sampling of peat archives. However, some concerns have been raised over the quality of the resultant proxy-climate records because changes in the plant species composition of peat may contribute a ‘species signal’ to records, potentially confusing the relationship between bog water table position and the apparent degree of peat humification. This paper uses the k-values of fresh plant material (sensuOverbeck, 1947 – i.e. the absorption value of the alkali extracts of fresh plant material) to explore the impact of changing plant colouration in a Holocene peat humification-based palaeoclimate archive from Newfoundland. We calculate k-scores for peat samples, using plant macrofossil data and the k-values of individual species to provide a down-core visualisation of the plant species signal. Although, overall, the humification data are validated, comparison of the original humification data with a k-adjusted version shows that the species signal is sometimes sufficient to change the timing and number of decadal to centennial-scale events recorded in the data as well as millennial to multi-millennial-scale trends
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