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The Geology Section (C) of the Leicester Literary and Philosophical Society presents: Cool Geology:
ice sheets past and present Annual Saturday Seminar 19 March 2011, 9.30am - 5.00pm Assemble from 9.00am; Reception to follow the Seminar Lecture Theatre 1, Bennett Building, University of Leicester |
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Glaciations have occurred throughout geological time, from early manifestations such as ‘Snowball Earth’ to our present day system of ice sheets and glaciers. Eight eminent scientists will review recent advances regarding the effects of glaciations on our climate and landscapes over time, including the sedimentology of glacial deposits. We will also look in detail at present-day ice sheets, their stability and what the record of ice can tell us about the composition of our atmosphere and climatic changes. The full day of talks will be presented by Professors Ian Fairchild, Mike Hambrey, John Smellie, and Eric Wolff, FRS and Drs Howard Armstrong, Tom Bradwell, Daniel Hill and Mark Williams, all highly regarded leaders in the field. |
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Seminar Programme |
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9.00 |
Assemble |
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| 9.30 |
Opening Mark Evans, Chairman, Geology Section (C), Leicester Literary and Philosophical Society |
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| 9.35 |
Introduction to Cool Geology: ice sheets past and present. Dr Mark Williams(University of Leicester). |
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| 9.50 |
Turning up the heat on Snowball Earth: new results from GAINS (Glacial Activity in Neoproterozoic Svalbard). Professor Ian Fairchild (University of Birmingham). |
10.35 |
Refreshment Break |
| 10.55 |
Visions of ice sheets in the Early Palaeozoic greenhouse world. Dr Howard Armstrong (University of Durham). |
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| 11.40 |
Britain's Glacial Landscapes - onshore and offshore perspectives. Dr. Tom Bradwell (British Geological Survey, Edinburgh). |
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| 12.25 |
Lunch |
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| 13.20 |
Frozen in time: ice cores and climate. Professor Eric Wolff, FRS (British Antarctic Survey, Cambridge). |
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| 14.05 |
Ice and climate: 70 million years of co-evolution. Dr. Daniel Hill (University of Leeds). |
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| 14.50 |
Refreshment Break |
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| 15.10 |
Evolution of the Antarctic Ice Sheet and implications for the future. Professor Mike Hambrey (University of Aberystwyth). |
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| 15.55 |
Antarctica - the largest glaciovolcanic province in the world and how its volcanic products can help to reconstruct past ice sheets. Professor John Smellie (University of Leicester). |
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16.40 |
Discussion and Concluding Remarks |
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17.15 |
Reception. To be held in Bennett Building |
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Seminar abstracts |
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Professor Ian Fairchild University of Birmingham.
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Abstract In the lively discourse resulting from the Snowball Earth hypothesis of Neoproterozoic glaciation, relatively little attention has been paid to the glacial sediments themselves, or to terrestrial environments. The succession in Svalbard (high-arctic Norway) is one of candidates to establish a global stratotype for the Cryogenian geological system. Sedimentological data shows that the onset of glacial conditions were more gradual than previously thought and the preservation of primary d18O signals in organogenic dolomite allows inferences to be made on climatic conditions. Svalbard also contains an apparently unique profile of glacilacustrine sediments that formed during the later Cryogenian (Marinoan) glaciations, including dolomites with the highest d18O signals and limestones with the lowest D17OSO4 values in the geological record. These give a vivid glimpse of a glacial world driven to high PCO2 conditions by inhibition of weathering accompanying extensive glaciations.  |
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Visions of ice sheets in the Early Palaeozoic greenhouse world. Dr Howard Armstrong University of Durham
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Abstract The Ordovician world was significantly different: the land was largely devoid of vegetation, atmospheric oxygen levels were ~50% PAL (present atmospheric level); sea levels were the highest in the Phanerozoic and large areas of the continents were submerged. Traditionally, an intense greenhouse climate has been postulated, maintained by higher (8 to 18x PAL) pCO2 levels; terminated by a short and intense end-Ordovician (Hirnantian) glaciation. However, a new research nexus is emerging. C-cycle models predict atmospheric CO2 values of 5 x PAL during the Middle Ordovician; and a global mean air temperature of 15oC consistent with δ18O values and biogeographical studies that indicate a modern-style “cool” world climate for the late Middle and Upper Ordovician. A Global Climate Model experiment parameterized with 8xPAL pCO2, high relative sea level, and a modern equator-to-pole heat transport returned a mean global surface temperature prediction of 16 °C for the early Late Ordovician. The same experiment also indicated polar temperatures low enough to sustain ice sheets, particularly at low sea levels and with pCO2 at 8x PAL. If by the Middle Ordovician, climate was essentially modern in character, polar ice would be expected. The focus of this contribution is to report on two research projects that yield palaeoclimate proxies and eustatic sea level records that indicate small/medium ice sheets were present during the Early and Middle Ordovician. This work implies the evolution of the Early Palaeozoic Ice Age has much in common with the ice-dominated Cenozoic. |
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Britain's Glacial Landscapes - onshore and offshore perspectives. Dr Tom Bradwell BGS, Edinburgh
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Abstract During the Last Glacial Maximum, when global sea levels were more than 100 m lower than today, a large ice sheet covered over two-thirds of the British Isles. Although the British-Irish Ice Sheet and its associated deposits have been extensively studied, the true dimensions of this palaeo-ice-sheet, particularly offshore, have remained unknown and have been strongly contested until recently. Using important new datasets this talk highlights recent breakthroughs, both onshore and offshore, that have allowed a better understanding of the size and dynamics of this former ice sheet. In particular, the talk will focus on the recent identification of palaeo ice streams and their geological legacy in the British landscape.
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Frozen in time: ice cores and climate. Professor Eric Wolff British Antarctic Survey, Cambridge
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Abstract The polar ice sheets hold one of Earth’s great sedimentary records. By drilling ice cores from Greenland and Antarctica, we can obtain ice that fell as snow, extending back so far 800,000 years in Antarctica and over 120,000 years in Greenland. Ice cores contain information about climate and numerous other environmental parameters; crucially the air bubbles trapped in the ice give access to the past composition of the atmosphere, including the greenhouse gas concentrations. In this talk I will first discuss the strengths and weaknesses of ice cores, and then demonstrate how ice cores are collected. I will then present a few examples of the knowledge we have gained from ice cores – about greenhouse gases, about glacial/interglacial cycles, and about rapid climate changes most likely induced by changes in ocean heat transport. Finally I will discuss prospects for obtaining even older ice in the future. .
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Ice and climate: 70 million years of co-evolution. Dr Daniel Hill University of Leeds
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Abstract Today, ice covers 6 million square miles, over 10% of the land surface and plays an important role in cooling the planet. Recent observations of rapid change in the glaciers that drain the world’s major ice sheets have surprised the scientific community and defied predictions from the current state-of-the-art ice sheet models. The uncertainties in the future evolution of global ice sheets are the largest single uncertainty in predictions of climate change and sea level rise. One of the ways to understand how global ice volumes may vary in future is to study how they have changed in the past. The Earth has undergone massive changes in climate over the last 70 million years. Since the warm climates experienced by the dinosaurs and the extreme warming events of the Eocene, the changing climate seems to inexorably linked with changes in global ice sheets. The Eocene-Oligocene boundary (~34 million years ago) is one of the most fundamental reorganisations of the climate. It corresponds to the initiation of major continent-wide glaciation on Antarctica. The Neogene (23-3 million years ago) saw major variations and changes in the Antarctic Ice Sheets, although the exact nature of these fluctuations remains enigmatic. In the Quaternary (last 3 million years) Northern Hemisphere ice sheets oscillate between ice sheets covering most of the land mass north of 60°N and similar-to-modern ice cover. Through the study of these past interactions between climate and ice sheets, both from modelling and proxy-based studies, we are beginning to understand just how interconnected these two systems are. However, the largest uncertainties seem to be in moderately warmer-than-modern palaeoclimates, such as the Neogene. Here, the proxy evidence is sparse and contradictory and the model predictions are highly dependent on the starting assumptions. As humans continue to emit CO2 and global mean temperatures continue to rise, the Earth will reach similar atmospheric CO2 levels and global temperatures over the coming century. Characterizing and understanding the behaviour of ice sheets in these enigmatic warm climates of the recent geological past offer a unique opportunity to test ice sheet and climate models and may ultimately enable us to better predict the future evolution of the Earth and its climate.
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Evolution of the Antarctic Ice Sheet and implications for the future. Professor Mike Hambrey University of Aberystwyth
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Abstract The geological record of Antarctic Ice Sheet evolution comes from substantial sequences of sediment drilled to depths of up to a kilometre on the continental shelf, as well as from more sketchy stratigraphic sections in the interior mountains. Spanning 34 million years, the record shows a dynamic ice sheet for the bulk of its history, starting off as a temperate ice mass that was accompanied by woodland vegetation, following by progressive cooling to the frigid ice sheet that has prevailed for the last 2 million years, with a near absence of vegetation. By comparing the past temperature record and the presence or absence of ice sheets, with the future projections of the Intergovernmental Panel on Climate Change, we see that global temperatures by 2100 AD will take us back to conditions that Earth has not experienced for several million years. This has major implications for the future stability of the ice sheet and a potential huge impact on sea level. |
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Professor John Smellie University of Leicester
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Abstract Antarctica is host to numerous volcanoes that were constructed over the past 25 million years. They were erupted in association with a coeval ice sheet, and Antarctica is the world¹s largest glaciovolcanic province. Glaciovolcanic studies have advanced significantly over the past 10 years and they are now capable of yielding the widest and most precise range of critical parameters of past ice sheets of any current methodology. Historically, they also played an important yet largely ignored part as the first unambiguous evidence for a pre-Quaternary ice sheet in Antarctica, and they are once again poised to make a fundamental contribution to our understanding of the history & development of the world¹s largest ice sheet. This talk will show examples of the many large and beautiful ice-clad volcanoes that crop out in a chain right across Antarctica and, by means of one or more case examples, will demonstrate how they are now being used to reconstruct parts of the Antarctic Ice Sheet (AIS). Studies such as these are important in assessing the stability of the AIS under the current phase of climate warming, and ultimately for calculating much more reliably the possible impacts on global sea levels. |