skip to primary navigation skip to content
 

Climate and Environmental Dynamics seminars: archive

Climate and Environmental Dynamics seminars: archive

Return to the list of forthcoming seminars.

# Monday 15th April 2019, 5.30pm - Prof. Felix Riede, Aarhus University
Moments of crisis – volcanic eruptions, environmental impacts and societal change in the northern European past
Venue: Large Lecture Theatre, Department of Geography, Downing Site

Richard Tipping and colleagues noted in 2012 that major societal transformations in Scottish prehistory can be seen as ‘moments of crisis’ precipitated by climate change. May such moments crisis have been more widespread in the past? In my lecture, I will build on this suggestion and focus on three such pivotal moments in the northern European past, from the deep time of the Late Pleistocene – the Laacher See eruption of 13,000 years ago – to the second millennium BCE – the Thera and/or Aniakchak eruptions of 3600 years ago – to the not at all so distant 6th century CE with its series of multiple compounding eruption events. I thus present three cases, one each from the Stone, Bronze and Iron Ages, where distant volcanic eruptions are implicated in societal change through their impacts on past lives and livelihoods. Finally, I place the study of such ancient calamities and the societal transformations they may have been involved in in a wider perspective that articulates with our contemporary predicaments of climate change and the societal challenges it poses.

# Thursday 28th March 2019, 4.00pm - Trond Dokken, Norwegian Research Centre, Bergen
The anatomy of abrupt climate change over Dansgaard-Oeschger cycles seen from the North Atlantic/Nordic Seas
Venue: Large Lecture Theatre, Department of Geography, Downing Site

Trond will give an overview of his recent work and highlights from the ongoing Ice2Ice ERC synergy project, with a focus on integration of high-resolution marine and Greenland ice core records. If you are interested in palaeoclimate, ocean circulation, sea ice dynamics and ice cores you should come along.

The seminar will be held at 4:00 pm in the Large Lecture Theatre at the Department of Geography, followed by a small wine reception.

# Thursday 22nd November 2018, 5.30pm - Prof. Francois Primeau (University of California Irvine, USA)
Global Estimates of Marine Nitrogen Fixation based on a Non-Redfield Inverse Model
Venue: Latimer Room, Clare College

Abstract not available

# Thursday 15th November 2018, 1.00pm - Prof Hans Linderholm, University of Gothenburg
Climate and human health in the last two millennia
Venue: William Hardy Building, Room 101, Department of Geography, Downing Site

Abstract not available

# Thursday 1st November 2018, 5.30pm - Dr Mario Krapp (Department of Zoology)
A comprehensive climate history of the last 800,000 years and its application to ecological modelling
Venue: Cripps Meeting Room 3, Magdalene College

Understanding ecosystems and their evolution through the climate of the Pleistocene ice ages requires detailed palaeo-climate reconstructions.
Global climate models (GCM) are frequently used to explore the many diverse aspect of past climates. However, due to their high computational demand a continuous and spatially detailed exploration of the past remains elusive. In this talk, I will present a GCM emulator, which is based on climate snapshot simulations of the last 120ka, that allows us to reconstruct the climate of the last 800,000 years (and
beyond) in a quasi-continuous way. I will show how the predictive skill of the GCM emulator can be tested against existing Pleistocene climate proxies and I will present a few highlights of how such an emulator can be used for ecological modelling, for example, the dispersal of anatomically modern humans out of Africa.

# Thursday 1st November 2018, 1.00pm - Dr Nick Blegen, University of Cambridge
World Enough & Time: Tephrostratigraphy and Modern Human Evolution in Middle-Late Pleistocene East Africa
Venue: William Hardy Building, Room 101, Department of Geography, Downing Site

Abstract not available

# Thursday 18th October 2018, 5.30pm - Prof. Ulf Buentgen (Department of Geography)
Re-thinking the boundaries of dendrochronology
Venue: Cripps Auditorium, Magdalene College

Abstract not available

# Thursday 18th October 2018, 1.00pm - Dr Ina Neugebauer, GFZ Potsdam (Visiting Scholar, Department of Geography, University of Cambridge)
Varves and tephras in the palaeoclimate record of the Dead Sea
Venue: William Hardy Building, Room 101, Department of Geography, Downing Site

Abstract not available

# Wednesday 3rd October 2018, 11.00am - Chuan-Chou Shen, National Taiwan University
Orbital-scale East Asian-Australian summer monsoon dynamics and a centennial earth magnetic reversal event at 98 ka
Venue: Seminar Room, Department of Geography, Downing Site

Previous studies of stalagmite-inferred East Asian summer monsoon (EASM) records over the past 100s kyr suggest that orbital-scale EASM intensity was predominately driven by precessional forcing of ~20 kyr. In the past years, we reconstructed a tropical precipitation record from the western Pacific since 282 ka, inferred from planktonic foraminiferal rare earth element contents of a marine sediment core collected off the eastern coast of Papua New Guinea. This record shows that the Australian summer monsoon (ASM) intensity was influenced by combined precession and obliquity changes. The obliquity forcing could be primarily delivered by a cross-hemispherical thermal/pressure contrast, resulting from the asymmetric continental configuration between Asia and Australia in a coupled East Asian-Australian circulation system. In this talk, I will also briefly introduce one of our recent studies on the stalagmite-inferred multidecadally-resolved geomagnetic record during 107-91 ka and an abrupt centennial polarity reversal event at 98 ka.

# Tuesday 15th May 2018, 1.00pm - Stefan Kröpelin, University of Cologne
The Eastern Sahara: From Holocene climate to prehistoric archaeology to the desert roots of Pharaonic civilisation and World Heritage
Venue: Seminar Room, Department of Geography, Downing Site

Abstract not available

# Thursday 26th April 2018, 5.30pm - Denis-Didier Rousseau - Laboratoire de Meteorologie Dynamique & CERES-ERTI
Record of abrupt changes of last climate cycle in European glacial dust deposits
Venue: Bawden Room, West Court, Jesus College

This presentation is an overview to the project ACTES, supported by the French ANR, and previous projects I conducted on European loess sequences. The main aim was to study the record of abrupt climate changes, corresponding to the Dansgaard-Oeschger and Heinrich events, in European terrestrial records, especially loess sequences. Loess is an eolian material that can be considered in a first order as “paleodust”. This study was designed as a data-model comparison to investigate how these sequences recorded the DO events in a periglacial environment, how the dust was emitted and deposition occurred, and from which source zones.

Europe has been strongly impacted by the millennial climate changes related to variations in the sea-ice extent and therefore also affected the moisture sources of precipitation on the Greenland ice sheet. These variations in the extent of the sea ice during the last climatic cycle (LCC, about 130-15 kyr) impacted the westerlies and the position of the polar jet stream, and consequently storm track trajectories. Furthermore, the presence of ice sheets and ice caps over Great Britain, Scandinavia and the Alps enhanced the zonal circulation, as recorded by the European paleodust deposits located along the 50°N parallel.

Loess sequences are well developed all over Europe, but especially in the so-called loess belt between 48° and 52°N. Such intensive deposition of paleodust over Europe has been favored by the reduced arboreal cover (even practically absent in NW Europe during both GS and GIs, by sea-level lowering, exposing large areas of the continental shelves to eolian erosion, and by strong increases in fluvial transport and sedimentation by periglacial braided rivers. Extensive investigations of European loess series along a longitudinal transect at 50°N reveal that the millennial-scale climate variations observed in the North-Atlantic marine and Greenland ice-core records are well preserved in loess sequences. Among them, the Nussloch loess site yields an important record of the LCC although its paleosol-loess unit couplet succession is not unique, but observed with a variable thickness and a diverse nature of the paleosols in sequences ranging from Western Europe eastward to Ukraine over more than 1800 km.
Recent numerical simulations of the past global dust cycle for the first time included glaciogenic dust sources and, compared to earlier attempts, resulted in an improved performance when confronted to data available for the Last Glacial Maximum. Still, even the improved modeling failed to capture spatial and temporal dynamics of past dust deposition. We achieve recently a step increase in understanding sub-continental scale climate change by identifying dust sources and constraining dust residence time in the atmosphere. Using dust deposition over Europe during the last glacial cycle, geochemical fingerprinting, and numerical dust emission simulations we identify the main aerosol sources for different depositional areas. Dust was transported at low elevation and over regional distances only. The glaciogenic sources considered so far in climate modeling, like frontal moraines and outwash plains of the European ice-sheets, were of considerably less relevance for the global dust budget than proposed earlier. The main contributors were regions between 48°and 52°N, with variable hot spots depending on climate conditions. Loess units are interpreted to correspond to coarse paleodust transported at rather low elevations, in the active layer of the atmosphere (about 300 to maximum 3000 m) at regional to local scales, while finer paleodust deposited at high latitudes seems transported at much higher elevations.

A recent study raised the problem in correctly estimating the sedimentation (SR) and mass accumulation (MAR) rates of the sequences for comparison with model estimates, which cannot be estimated by just taking into account the whole thickness of the considered deposits as classically performed. To solve this issue, Greenland ice and northwestern European eolian deposits are compared in order to establish a link between GI and the soil development in European mid-latitudes, as recorded in loess sequences. For the different types of observed paleosols, the precise correlation with the Greenland records is applied to propose estimates of the maximum time lapses needed to achieve the different degrees of maturation and development. To identify these time lapses more precisely, two independent ice-core records are compared: d180 and dust concentration, indicating variations of temperature and atmospheric dustiness respectively in the Greenland area. This method slightly differs from the definition of a GI event duration applied in other studies where the sharp end of the d18O decrease gives the end of a GI. The same methodology is applied to both records (i.e., the GI last from the beginning of the abrupt d18O increase or dust concentration decrease until when d18O or dust reach again their initial value) determined both visually and algorithmically, and compare them to GI published estimates.

# Friday 9th March 2018, 2.00pm - Lisa Bröder
Climate Environmental Dynamics Research Group Seminar
Quantifying transport time and degradation of terrigenous organic carbon across the East Siberian Arctic shelf
Venue: Small Lecture Theatre, Department of Geography, Downing Site

Permafrost soils in the Arctic store large quantities of organic matter, roughly twice the amount of carbon that was present in the atmosphere before the industrial revolution. This freeze-locked carbon pool is susceptible to thawing caused by amplified global warming at high latitudes. The remobilization of old permafrost carbon facilitates its degradation to carbon dioxide and methane, thereby providing a positive feedback to climate change.

Accelerating coastal erosion in addition to projected rising river discharge with enhancing sediment loads are anticipated to transport increasing amounts of land-derived organic carbon (OC) to the Arctic Ocean. On its shallow continental shelves, this material may be remineralized in the water column or in the sediments, transported without being altered off shelf towards the deep sea of the Arctic Interior or buried in marine sediments and hence sequestered from the contemporary carbon cycle. The fate of terrigenous material in the marine environment, though offering potentially important mechanisms to either strengthen or attenuate the permafrost-carbon climate feedback, is so far insufficiently understood.

We have used sediments from the wide East Siberian Arctic Shelf, the world’s largest shelf-sea system, to investigate some of the key processes for OC cycling. A range of bulk sediment properties, carbon isotopes and molecular markers were employed to elucidate the relative importance of different organic matter sources, the role of cross-shelf transport and the relevance of degradation during transport and after burial.

This talk focuses on how we can employ compound-specific radiocarbon analyses of terrestrial biomarkers to determine cross-shelf transport times and quantify degradation rates for terrigenous OC (terrOC). For the 600 km from the Lena River Delta to the Laptev Sea shelf edge our quantitative estimate resulted in 3600 ± 300 years. During transport, terrOC was reduced by ~85%, thus yielding a degradation rate constant of 2.4 ± 0.6 kyr-1. Hence, terrOC degradation during cross-shelf transport constitutes a carbon source to the atmosphere over millennial time. For the contemporary carbon cycle on the other hand, slow terrOC degradation brings considerable attenuation of the decadal-centennial permafrost carbon-climate feedback caused by global warming.

# Thursday 8th March 2018, 5.30pm - Barbara Maher, Lancaster University
Recent developments and debates in East Asian monsoon palaeoclimatology
Venue: Latimer Room (Old Court), Clare College, Trinity Lane

Quaternary rainfall reconstructions for the monsoon-dominated region of East Asia remain both of critical importance for testing general circulation model estimates of past and future rainfall for this populous region, and intensely debated. The oxygen isotope variations of the well-dated Chinese speleothem records have been very widely perceived as proxies of summer monsoon intensity and summer rainfall totals. Mass balance calculations demonstrate that extremely large changes in rainfall are required in order to generate the magnitude of oxygen isotope variations seen both within the Holocene and over glacial and interglacial timescales throughout the Quaternary. Rainfall proxy records derived from the famous loess/palaeosol sequences of the Chinese Loess Plateau do not accord with the cave records (and are rarely if ever discussed by the cave science community). Here, the key areas of debate will be explored. The possible dominance of Pacific- rather than North Atlantic-sourced influences on the East Asia monsoon will also be discussed.

A Quaternary Discussion Group seminar

# Thursday 8th March 2018, 4.15pm - Dr Walter Immerzeel, Faculty of Geosciences, Universiteit Utrecht, The Netherlands
CANCELLED DUE TO STRIKE ACTION Recent advances in understanding climate, glacier and river dynamics in high mountain Asia
Venue: Small Lecture Theatre, Department of Geography, Downing Site

The water cycle in the Himalaya is poorly understood because of its extreme topography that results in complex interactions between climate, water stored in snow and glaciers and the hydrological processes. Hydrological extremes in the greater Himalayas regularly cause great damage, while high mountain Asia also supplies water to over 25% of the global population. So, the stakes are high and an accurate understanding of the Himalayan water cycle is imperative. The hydrology of the greater Himalayas is only marginally resolved due to the intricacy of monsoon dynamics, the poorly quantified dependence on the cryosphere and the physical constraints of doing research in high-altitude and generally inaccessible terrain. However, in recent years significant scientific advances have been made in field monitoring, modelling and remote sensing and the latest progress and outstanding challenges will be presented for three related fields. First focus will be on recent learnings about high altitude climate dynamics and the interaction between the atmosphere and the extreme mountain topography. Secondly, recent advances in how climate controls key glacio-hydrological processes in high-altitude catchments will be discussed with a particular focus on debris covered glaciers. Thirdly, new developments in glacio-hydrological modelling and approaches to climate change impact assessments will be reviewed. Finally, the outstanding scientific challenges will be synthesized that need to be addressed to fully close the high mountain water cycle and to be able to reduce the uncertainty in future projections of water availability and the occurrence of extreme events in high mountain Asia.

# Thursday 8th March 2018, 4.15pm - Walter Immerzeel, University of Utrecht
THIS TALK HAS BEEN CANCELLED DUE TO STRIKE ACTION
CANCELLED DUE TO STRIKE ACTION Recent advances in understanding climate, glacier and river dynamics in high mountain Asia
Venue: Small Lecture Theatre, Department of Geography, Downing Site

The Himalayan water cycle is poorly understood because the extreme topography results in complex interactions between climate, water stored in snow and glaciers and the hydrological processes. An accurate understanding of this water cycle is imperative because hydrological extremes in the region regularly cause great damage, while high mountain Asia supplies water to over 25% of the global population. In recent years, significant advances have been made in field monitoring, modelling and remote sensing and in this talk, the latest progress will be presented focussing on three related fields. First, on high altitude climate dynamics and the interaction between the atmosphere and the extreme mountain topography. Second, on how climate controls key glacio-hydrological processes in high-altitude catchments with a particular focus on debris covered glaciers. Third, on glacio-hydrological modelling and approaches to climate change impact assessments. Finally, the talk will synthesize the outstanding scientific challenges that must be addressed to fully close the high mountain water cycle, thereby reducing the uncertainty in future projections of water availability and the occurrence of extreme events in high mountain Asia.

# Thursday 1st March 2018, 1.00pm - Francesco Muschitiello ( Department of Geography, University of Cambridge)
Deep-water circulation changes lead North Atlantic climate during deglaciation
Venue: Rm 101, William Hardy Building, Department of Geography, Downing Site

Constraining the response time of the climate system to changes in Atlantic Meridional Overturning Circulation (AMOC) is essential to improving future climate predictability. Here we present a precise synchronization of terrestrial, marine, and ice-core records, which allows for the first time a quantitative determination of the response time of North Atlantic climate to changes in AMOC strength during the last deglaciation. Using a continuous record of deep-water ventilation from the Nordic Seas, we identify a systematic ∼300-year lead of changes in deep-water convection ahead of abrupt climate changes recorded in Greenland ice cores at the onset and end of the Younger Dryas stadial (YD), which likely occurred in response to gradual changes in freshwater forcing. Supported by transient climate model simulations, our results also indicate a ~400-year delay in the rise of atmospheric CO2 in response to AMOC slowdown at the start of the YD. We conclude that variations in North Atlantic deep-water formation are precursors to large-scale climate and pCO2 changes, highlighting the need for improved long-term future AMOC projections.

# Thursday 22nd February 2018, 5.30pm - Andrey Ganopolski, Potsdam Institute for Climate Impact Research
Normal time and place
Modeling and understanding of Quaternary climate cycles
Venue: Latimer Room (Old Court), Clare College, Trinity Lane

In spite of significant progress achieved in recent decades in understanding of Quaternary climate dynamics, there are still a number of important questions remained to be answered. Among them is the cause of Mid-Pleistocene transition (MPT). To address this questions we used the Earth system model of intermediate complexity CLIMBER-2 which incorporates all major components of the Earth system – atmosphere, ocean, land surface, northern hemisphere ice sheets, terrestrial biota and soil carbon, aeolian dust and marine biogeochemistry. We performed a set of simulations covering the entire Quaternary using as the only forcing variations in Earth orbital parameters and gradually evolving in time land-ocean distribution and terrestrial sediment cover. We found that a gradual removal of terrestrial sediment from the Northern Hemisphere continent by glacial processes is sufficient to explain transition from 40-ka to 100-ka worlds around the MPT. Gradual change in volcanic outgassing or weathering rate during Quaternary is required to explain early Pleistocene climate dynamics. Our results strongly suggest that Quaternary glacial cycles are externally forced and almost deterministic.

Quaternary Discussion Group seminar

# Wednesday 21st February 2018, 5.00pm - Professor Dorthe Dahl-Jensen, Niels Bohr Institute, University of Copenhagen
Distinguished International Visiting Fellow Lecture
Greenland ice cores tell tales on past sea level changes
Venue: Large Lecture Theatre, Department of Geography, Downing Site

Abstract not available

# Thursday 15th February 2018, 1.00pm - Fredrik Charpentier Ljungqvist, Department of History, Bolin Centre for Climate Research, Stockholm University
Reconciling centennial-scale climate variation during the last millennium in reconstructions and simulations
Venue: Rm 101, William Hardy Building, Department of Geography, Downing Site

With some thoughts on the usefulness of climate history

Our two principal sources of climate variability over the past millennium and beyond are proxy-based reconstructions and model simulations. Though the two share broad agreement, model simulations typically possess less centennial-scale variability than reconstructions. I will provide an overview of the discrepancies between temperature and hydroclimate reconstructions, and last millennium simulations of the same two parameters, and discuss how the differences might be reconciled. Lastly, I will give a few examples in the usefulness of climate history to understand both ongoing climate change and past human history.

Dr. Fredrik Charpentier Ljungqvist is a Swedish historian and palaeoclimatologist from Stockholm University and is at present Visiting Researcher at the Department of Geography, University of Cambridge.

# Thursday 8th February 2018, 5.30pm - Alex Piotrowski (Dept of Earth Science)
Reconstructing deep ocean circulation pathway and strength using sediment dispersion
Venue: Latimer Room (Old Court), Clare College, Trinity Lane

Ocean circulation is thought to play a key role in the Earth’s climate system because surface ocean currents transport heat from the equator to the poles and deep ocean water sequesters carbon dioxide from the atmosphere. Geochemical proxies measured on the biogenic components of marine sediments have been widely-utilized to reconstruct past ocean changes. However, because these proxies are controlled by biology and chemistry in addition to physical circulation it is difficult to use them to quantitatively reconstruct physical oceanographic parameters such as deep water advection speed. I will present new data of coupled sediment grainsize and source measurements, from highly resolved grain-size separates across the clay and silt fraction, allowing reconstruction of the dispersion of fine detrital sediment by ocean currents. We have initially worked in the North Atlantic because it hosts a strong deep current that transports sediment from geological sources with distinct and well-constrained geochemistry (i.e. Iceland and the Canadian Shield). Our core-top data shows that grainsize separation in the 0-63 m range allows “unmixing” of North Atlantic marine sediment samples into at least three different sources; the finest grain-sizes are derived from Scandinavia and Iceland and have been transported great distances by deep current flow, while the coarser fractions are locally derived. Time slice reconstruction during the last deglaciation place new constraints on glacial-interglacial changes in sediment sources, input, and ocean circulation pathways.

Quaternary Discussion Group seminar

# Monday 5th February 2018, 2.15pm - David Wade, Cambridge University
Fundamental Limits to Volcanic Cooling and its Implications for Past Climate on Earth
Venue: Pfizer Lecture Theatre, Department of Chemistry

Volcanic eruptions are the dominant cause of short-term climatic cooling through their emission of aerosol precursor gases. This cooling response has been invoked to explain a number of climatic transitions: from the little ice age in Northern Europe to causing a completely ice-covered world. However, there are physical limits to the strength of volcanic cooling from a single eruption. I will present two case studies to support this: the eruption of Samalas (1257) and the eruption of the Franklin Large Igneous Province (~700 Mya).

The eruption of Samalas resulted in the largest stratospheric injection of volatile gases in the Common Era. However, the cooling response modelled for the Past1000 experiment in the CMIP5-PMIP3 model intercomparison experiment are overestimated compared to tree-ring proxy archives. Large ensemble simulations of the past 1000 years have also been performed with CESM [1]. However, these also overestimate the cooling, by around 2-3 times. I will present the results of simulations using a novel configuration of the HadGEM-AO climate model, validated for the climate response to the Mount Pinatubo eruption in 1991, to show that the muted climate response is consistent with our current understanding of the chemical and physical processes which determine the climate response. I will also highlight the crucial role of internal climate variability and the challenges this poses for interpreting the climate response directly from tree rings.

740 million years ago, Earth entered a prolonged period where glaciers reached the tropics, a so-called “Snowball Earth” episode. Recent work by Macdonald and Wordsworth [2] has suggested that annually-paced explosive eruptions from the Franklin Large Igneous Province could have caused this snowball Earth. I will present the results of simulations using HadCM3L, a coupled atmosphere-ocean circulation model, run under Neoproterozoic background conditions with plausible aerosol loadings and size distributions based on the volcanological reconstructions. These show that for size distributions consistent with such large eruptions, even a 25-times Pinatubo forcing is insufficient to cause a snowball Earth state. Microphysical simulations with HadGEM-A show the peak cooling due to annually-paced volcanic eruptions occurs in the 1-5 -times Pinatubo range, suggesting an even smaller limit to the magnitude of volcanic cooling by stratospheric injections of aerosol precursors. Such strong cooling has also been invoked for the end Cretaceous bolide event – Brugger et al [3] simulate a 26 C cooling using sulfate emissions, which is entirely implausible given the known physical and chemical processes.

These results suggest previous modelling studies have overestimated the cooling response to large volcanic eruptions. This has important implications for our understanding of the role of volcanic forcing of past climate. Extreme caution should therefore be exercised before invoking volcanic forcing as the dominant cause of a climatic transition based on models with poor (or no) representations of aerosol microphysics or atmospheric dynamics.

[1] BL Otto-Bliesner et al, Climate Variability and Change since 850 C.E. : An Ensemble Approach with the Community Earth System Model (CESM), 2016, BAMS

[2] FA Macdonald and R Wordsworth, Initiation of Snowball Earth with volcanic sulfur aerosol emissions, 2017, GRL

[3] J Brugger et al, Baby, it’s cold outside: Climate model simulations of the effects of the asteroid impact at the end of the Cretaceous, 2017, GRL

# Thursday 1st February 2018, 5.00pm - Samuel Jaccard, University of Bern
Please note different time/venue
On the role of the Southern Ocean in modulating (past) climate variability
Venue: Harker 1, Department of Earth Sciences, Downing Street

Quaternary Discussion Group seminar

# Thursday 1st February 2018, 1.00pm - Dr. Eimear M. Dunne (University of Cambridge)
Wind shear and mid-level convection in the Convective Cloud Field Model (CCFM)
Venue: Rm 101, William Hardy Building, Department of Geography, Downing Site

Clouds are an important part of the Earth’s climate system, both in radiative terms and in terms of transport of heat and moisture. But because clouds are so much smaller than grid boxes in global climate models, their behaviour needs to be parameterised – represented simply in terms of large-scale quantities. While most parameterisations use a single, average cloud to represent a whole grid box, CCFM generates a spectrum of possible clouds and then tracks their evolution using a model of predators competing for available resources (in this case, buoyant energy).

I will present a basic background of how CCFM works, and then describe the effects of two improvements on the published version of CCFM.

# Thursday 25th January 2018, 5.30pm - Phil Hughes, University of Manchester
Please note different venue
Reconstructing the extent, timing and palaeoclimatic significance of Quaternary glaciations in the Mediterranean region
Venue: Castlereagh Room, Fisher Building, St Johns College, Cambridge

Glaciation has affected many Mediterranean mountains on multiple occasions through the Quaternary. In the Pleistocene, glaciers were extensive and the altitudinal pattern of glaciation closely matches the modern distribution of precipitation, with some of the lowest glaciers forming in the western Balkans and northwestern Iberia. Conversely, the highest glaciers formed in areas that are currently the hottest and driest of the Mediterranean, such as in Morocco and central Turkey. In the western Balkans, ice caps covered large areas of Croatia, Montenegro and Albania. Further south in Greece, ice caps, plateau ice fields and valley glaciers were widespread throughout the Pindus Mountains. The largest glaciers of the Balkans formed during the Middle Pleistocene, although substantial cirque and valley glaciers were also present during the Late Pleistocene. In the western Mediterranean, ice caps and plateau ice fields formed over many of the mountains of Iberia and even in Morocco. Understanding the extent and timings of glaciations in this region is important for understanding landscape evolution and the effects of global climate change on the Mediterranean region. In recent years the timing of glaciations during the late Pleistocene has been revolutionised using cosmogenic exposure dating, revealing asynchronous glacier behaviour across the Mediterranean through the last cold stage. There is also evidence that small glaciers survived into the Holocene. Today, only a few small niche glaciers survive. These modern glaciers are much smaller than 150 years ago at the end of the Little Ice Age when Mediterranean glaciers were much more common.

# Thursday 18th January 2018, 1.00pm - Paul Krusic - Department of Geography, University of Cambridge
Dendrochronology in the Kingdom of Bhutan
Venue: Rm 101, William Hardy Building, Department of Geography, Downing Site

Since 2002 current University of Cambridge, Department of Geography researchers, in partnership with scientists from Columbia University’s Lamont-Doherty Earth Observatory, have been working advisors to Bhutan’s Ministry of Agriculture, Department of Forests and Parks. Originally invited to asses a perceived “forest decline” this collaborations activities now extend to providing education and capacity to Bhutan’s young and growing community of environmental managers and scientists. In this short presentation I will present some of the many highlights from this project, including visits to the classrooms, the forests, and Parliament. Tucked in amongst the scenery, will be some science describing results in both applied and theoretical Dendrochronology, a tool apply suited for the world’s youngest democracy with a self-imposed, constitutional mandate requiring national forest cover never fall below 60%, and land-cover under conservation below 50.

# Thursday 30th November 2017, 5.30pm - Paola Moffa Sanchez, Cardiff University
Quaternary Discussion Group seminar
North Atlantic variability and its link to European climate and history over the last 3000 years
Venue: Latimer Room (Old Court), Clare College, Trinity Lane

The subpolar North Atlantic is a key location for the Earth’s climate system. In the Labrador Sea, intense winter air–sea heat exchange drives the formation of deep waters and the surface circulation of warm waters around the subpolar gyre. This process therefore has the ability to formation of Labrador Sea Water. Yet, crucially, its longer-term history and links with European climate remain limited. We present new decadally-resolved marine proxy
reconstructions which suggest weakened Labrador Sea Water formation and gyre strength with similar timing to the centennial cold periods recorded in terrestrial climate archives and historical records over the last 3000 years. These new data support that subpolar North Atlantic
circulation changes, likely forced by increased southward flow of Arctic waters, contributed to modulating the climate of Europe with important societal impacts as revealed in European history.

# Tuesday 28th November 2017, 12.00pm - Dr Jennifer Morris, University of Cardiff
Deep time continental weathering and climate change in the Palaeozoic
Venue: Tilley Lecture Theatre, Department of Earth Sciences, Downing Site

Abstract not available

# Thursday 23rd November 2017, 4.15pm - Dr Richard Streeter, School of Geography and Sustainable Development, University of St Andrews
Measuring landscape resilience: tephra, soil and spatial patterns
Venue: Small Lecture Theatre, Department of Geography, Downing Site

A key challenge this paper addresses is understanding how and when landscapes are likely to become degraded. The concept of ecological ‘resilience’ and the related idea that there are generic ‘early warning signals’ prior to changes in state have created the possibility that we might be able to quantify the vulnerability of systems to change. This paper highlights the possibilities for both using both tephra layers (layers of volcanic ash) and the analysis of spatial patterns of erosion as approaches to understanding the resilience of landscapes, past and present. When tephra falls onto vegetated surface its thickness reflects aspects of the vegetation structure at the time. These variations in tephra thickness preserve information that can be used to assess the resilience of the land surface at the time of the eruption. This approach could be used to assess land surface resilience in the past. Using UAV imagery we can quickly and easily capture high-resolution images from currently eroding landscapes. These images are used to generate metrics such as patch-size distributions, which can be used to assess present landscape resilience. This paper will review these approaches and report on findings from fieldwork in the sub-arctic landscapes of Iceland.

# Thursday 23rd November 2017, 1.00pm - Dr Rachael Turton, Department of Geography, University of Cambridge
Developing land surface and vegetation models... by a field working ecologist!
Venue: Rm 101, William Hardy Building, Department of Geography, Downing Site

I’m going to give a two part presentation, firstly on my PhD research on snow-vegetation interactions in JULES (Joint UK Land Environment Simulator), the UK land surface model. Secondly, I’ll introduce my PDRA on representing plant growth processes in the HYBRID vegetation model, using data from a novel chilling experiment at Harvard Forest.

The radiative balance of sparse seasonally snow-covered forests are poorly represented within land surface models. High latitudes sparse canopies appear dense and impenetrable in early spring due to low solar elevation. Shortwave radiation penetration is highly spatial and temporally variable, and long shadows are cast over the snow surface. Yet incident shortwave radiation acts to increase longwave radiation to the snow surface. Field measurements are used to parameterise a new shaded gap tile, which improves the land-surface snow interactions in the JULES model.

Current global vegetation models drive plant growth with photosynthesis, which is controlled by light, temperature, water, and CO2. In this way they are able to reproduce the historical land carbon sink as a consequence of CO2 fertilization. However, experimental work suggests that the vegetation response to rising CO2 is strongly limited by the sink (growth) capacity of the tree rather than the source (photosynthesis) under natural conditions. Studies have shown high concentrations of non-structural carbon (a product of photosynthesis) observed in wood, thus indicating photosynthesis is not limiting tree growth, at least in the short-term. Observations on mature pine, maple, and oak trees at Harvard Forest will be used to incorporate the processes controlling growth and wood development within a sink-limited vegetation model, which will examine the implications for the historical and future global carbon balance.

# Thursday 16th November 2017, 6.45pm - Harriet Allen
Origins of Mediterranean flora
Venue: David Attenborough Building, New Museums Site, Pembroke St., Cambridge, CB2 3QZ

Harriet Allen, a biogeographer in the Department of Geography with
extensive fieldwork experience in a number of Mediterranean countries
and habitats, will talk about aspects of the vegetation, including its origins
and development, relationship to biodiversity and conservation.

# Thursday 16th November 2017, 5.30pm - Angela Gallego-Sala, University of Exeter
Climatic controls on peatland carbon accumulation during the last millennium
Venue: Latimer Room (Old Court), Clare College, Trinity Lane

Peatland ecosystems are a small but persistent sink of carbon and currently store more than 600 Pg C globally. Peatlands preserve a stratigraphic record of net carbon accumulation, the net outcome of plant respiration and respiration. The rates of both these processes will increase with warming and an important question is which of these will dominate the overall response of the global peatland carbon sink to future climatic changes. In this seminar, I will present the results of a global study of changes in peatland carbon accumulation rates over the last millennium. This study explores the relationship between carbon accumulation rates over the last millennium and modern climate space. The results indicate that there is a positive relationship between carbon accumulation and photosynthetically active radiation for mid- to high-latitude peatlands in both hemispheres, i.e. carbon accumulation is lowest at high latitudes where PAR0 is lowest. However, this relationship reverses for sites at lower latitudes, suggesting that carbon accumulation is reduced under the warmest climate regimes. This is important because it highlights that there are limits to the predicted negative feedback of the peatland carbon sink to warming. I will additionally present modelled future projections under RCP2.6 and RCP8.5 scenarios to explain that the overall peatland negative feedback does not necessarily persist in time.

# Thursday 9th November 2017, 1.00pm - Dr Alma Piermattei, Department of Geography, University of Cambridge
Tree-rings and genetics
Venue: Rm 101, William Hardy Building, Department of Geography, Downing Site

Alma joined CED as a Technical Laboratory Research Assistant, working with Prof Ulf Büntgen and Prof Christine Lane, last year. She has previously worked on forests in Italy and Germany, and has recently published on integrating dendrochronological and sclerochronological records in Iceland.

She will be discussing her recent post doctoral work at the Swiss Federal Research Institute (alongside Ulf Büntgen) which looks at the influence of genetic structure on tree growth and growth-climate relationships at individual and population level.

# Tuesday 7th November 2017, 12.00pm - Prof. Sanjeev Gupta, Imperial College London
Influence of Himalayan river dynamics on the Bronze-age Indus Civilisation in NW India
Venue: Tilley Lecture Theatre, Department of Earth Sciences, Downing Site

Alluvial landscapes built by large perennial rivers form the environmental templates on which the earliest urban societies nucleated. Large-scale spatiotemporal settlement patterns in these societies are postulated to have been influenced by river migration across alluvial floodplains. During the early to mid-third millennium BCE, the Indus Civilisation developed one of the most extensive urban cultures in the Old World. This civilisation was established on the alluvial plains of the Indo-Gangetic basin in northwestern India and Pakistan, with an urban phase commencing ~4.6-4.5 ka B.P. It was contemporaneous with and more extensive in area than the earliest urban societies of Egypt and Mesopotamia, encompassing an area estimated at ~1 million km2. Urbanism here has been linked to water resources provided by large Himalayan river systems, however the largest concentrations of urban-scale Indus settlements are located far from extant Himalayan rivers. Why numerous Indus settlements should have been located in a region now devoid of large perennial rivers has been the subject of vigorous debate and controversy.

In this talk, I present geological data to resolve the long-standing issue of the drainage evolution of rivers on the northwestern Ganges Plains by characterising the nature of late Quaternary fluvial deposition, up to and including the time of Indus Civilisation urbanisation. Using optically-stimulated luminescence chronologies, and U-Pb detrital zircon and Ar-Ar mica provenance fingerprinting, we constrain the timing and sources of the fluvial deposits. When dove-tailed with sedimentological analysis, our results demonstrate how river morphodynamics influenced Indus settlement patterns albeit in a counterintuitive fashion.

# Thursday 2nd November 2017, 5.30pm - Francis Wenban-Smith, University of Southampton
MIS 7, The "Ebbsfleet Interglacial": sub-stage structure and recognition in the UK record
Venue: Latimer Room (Old Court), Clare College, Trinity Lane

More than 20 UK Quaternary sites are reliably related to MIS 7 of the global marine isotope stage framework. This interglacial has a distinctive O18:O16 profile of an early warm peak (MIS 7e) followed by a well-defined cooler episode (MIS 7d), which is followed in turn by a double warm peak (MIS 7c and MIS 7a) divided by a minor cool episode (MIS 7b). Foremost among UK MIS 7 sites is the Ebbsfleet Valley, a
minor tributary on the south side of the Thames estuary. Here, approximately half a dozen separate localities have provided evidence of sequences from MIS 7, ranging from localities first investigated in the 1930s to currently-unpublished localities investigated as part of the HS1 archaeological programme. When the disparate palaeo-environmental, litho-stratigraphic and dating evidence from
these Ebbsfleet localities is considered as a whole, a picture emerges in which all three warm MIS 7 peaks can be recognised and distinguished from each other, and their distinctive palaeo-environmental and biostratigraphic characteristics can thus provide the framework within which other UK sites should be integrated.

# Thursday 2nd November 2017, 1.00pm - Pete Smith, University of Aberdeen
Managing the global land resource
Venue: Department of Plant Sciences, Large Lecture Theatre

With a growing population with changing demands, competition for the global land resource is increasing. We need to feed a projected population of ~12 billion by 2100, and might also need to deliver land-based greenhouse gas removal for climate change mitigation. Managing these conflicts is a major global challenge. I will discuss some of the challenges, synergies, trade-offs and possible solutions.

Prof. Pete Smith (FRS, FRSE, FRSB) is Professor of Soils and Global Change at the Institute of Biological and Environmental Sciences at the University of Aberdeen and Science Director of the Scottish Climate Change Centre of Expertise (ClimateXChange). Since 1996, he has served as Convening Lead Author, Lead Author and Author for the Intergovernmental Panel on Climate (IPCC). His interests are in climate change mitigation and impacts, greenhouse gases, fluxes, ecosystem modelling, soils, agriculture, bioenergy and food security.

# Tuesday 31st October 2017, 11.00am - Jonathan Holmes, University College London
Oxygen-isotope records of the Early Holocene climate of Europe
Venue: British Antarctic Survey, Innovation Centre, Seminar Room 1

The transition from the late glacial interval to the early Holocene was characterized by abrupt warming in the northern hemisphere middle and high latitudes broadly associated with a peak in orbitally-forced summer insolation. However, palaeotemperature reconstructions from marine and terrestrial archives as well as modeling investigations indicate that there were marked geographical variations in the timing of peak warmth associated with the so-called Holocene Thermal Maximum (HTM). Remnant Laurentide and Fennoscandian ice sheets, which persisted into the mid Holocene, delayed the HTM until around 8 – 7.5 ka BP in some regions as a result of albedo-sea ice feedbacks, changes in atmospheric circulation, and the slowing of North Atlantic convection by meltwater. However, despite previous attempts to characterize the nature of early to mid Holocene climate, palaeoclimate data and modeling experiments do not always agree and the relative importance of changes in temperature versus precipitation and the extent of shifts in atmospheric circulation, remain unclear. Oxygen-isotope values of precipitation are valuable tracers of past climate. We compiled published and unpublished oxygen-isotope records from lacustrine and speleothem carbonates from across western and central Europe as a proxy for the isotope composition of past precipitation, in order to investigate early to mid Holocene climate. We compare the geological data with results of experiments with the isotope-enabled GCM HadCM3. Temporal and geographical patterns show poor agreement with previous palaeotemperature reconstructions, but are consistent with a change in atmospheric conditions in the early to mid Holocene, associated with a weakening of the westerly circulation.

# Thursday 26th October 2017, 1.00pm - Dr Catherine Martin-Jones, Department of Geography, University of Cambridge
Chronicling Ethiopia’s explosive volcanic past using lake sediments
Venue: Rm 101, William Hardy Building, Department of Geography, Downing Site

The volcanoes of the Ethiopian Rift Valley are some of the least studied on Earth. Of the sixty-five currently active volcanoes in the region, forty-nine have no recorded historical eruptions. Accessing these volcanoes can prove a logistical challenge, and poor exposure at the volcano may hinder investigation of past eruption frequency and magnitude. To address this shortfall, we study sediment cores from seven Ethiopian lakes and construct the region’s first Holocene record of volcanism.

Volcanic ash (tephra) preserved in these stratigraphically-resolved lake sequences catalogue explosive eruptions through time. A tephra layer can be traced to its volcanic source and identified at different lake sites based on its geochemistry, allowing the tephra dispersal to be mapped. Lake sediments are also well-suited to radiocarbon dating, and these dates used to build Bayesian age models and understand the timing of past eruptions.

Our first eruption record reveals that Ethiopian volcanoes have erupted frequently and explosively throughout the Holocene, and therefore present a real, previously underestimated risk, to the rapidly developing population. Lake sediment tephra records show significant potential for reconstructing past volcanism throughout East Africa, work essential to clarifying and reducing today’s volcanic hazards.

# Thursday 19th October 2017, 5.30pm - Michael Sigl, Paul Scherrer Institut & Oeschger Centre for Climate Change Research, University of Bern
Volcanic eruptions, climate and humans: How lessons from the past can help us to prepare for the future
Venue: Latimer Room (Old Court), Clare College, Trinity Lane

Large volcanic eruptions are a major driver of natural climate variability responsible for numerous cooling extremes and throughout human history have often been followed by severe famines and pandemics. Spanning from the last glacial maximum into the future, I present case studies of how volcanic eruptions can impact our climate with implications for human societies in past, present and future. From pre-anthropogenic ozone depletion to “failures” of the critical Nile summer flood causing famines in Ancient Egypt, I track the influence of volcanic eruptions on climate and human societies and demonstrate that the significance of volcanic eruptions goes beyond a short-lived reduction of surface temperatures (e.g., “Year without a Summer”).

# Thursday 19th October 2017, 3.30pm - Professor Christine Lane and Professor Ulf Büntgen, Department of Geography, University of Cambridge
Under the Physical Geography Parasol: Climate and History
Venue: Small Lecture Theatre, Department of Geography, Downing Site

Professor Christine Lane: Timing is everything. Using tephra to explore past climate and environmental change.

Understanding the spatial and temporal variability of climate forcing as well as human and palaeoenvironmental responses to change, relies upon comparison of data from widespread terrestrial, glacial and marine archives. Building accurate, precise and independent chronologies for palaeoclimate, palaeoenvironmental and archaeological records is essential; however this remains a major challenge in many environments and often prevents the valid comparison of detailed palaeo-proxy records. In the Cambridge Tephra Lab we are using far-travelled volcanic ash tie-lines to tackle these issues and to address interdisciplinary research questions. This talk will focus on on-going investigations into the presence of visible and non-visible (crypto-) tephra layers within lacustrine palaeoenvironmental records of the last ~150 ka BP from across East Africa. With this approach we are revealing the potential to (i) precisely correlate, and therefore robustly compare, palaeoclimate archives from across and beyond tropical Africa within a regional tephrostratigraphic framework; (ii) provide chronologies for individual lake sediment palaeoclimate records, in particular beyond the limits of radiocarbon dating; (iii) increase our knowledge of the history of Late Quaternary explosive volcanism in East Africa; and (iv) explore the environmental impacts of major volcanic eruptions, which are believed to have had global climate effects.

Professor Ulf Büntgen: A tree-ring perspective on climate and history.

In this talk, I will focus on novel tree ring-based, proxy evidence of the European Alps and the Russian Altai-Sayan Mountains in Inner Eurasia. While stressing data-inherent and methodological-induced limitations of the existing high-resolution, summer temperature reconstructions, I will emphasize their spatiotemporal coherency and ability to link past climate variability with human history. Large-scale peopolitical and socio-cultural transformations during the Late Antique Little Ice Age between 536 and ~660 CE (LALIA), the sudden withdrawal of the Mongols from the Hungarian Plain in 1242 CE, and the unprecedented rate and magnitude of dispersal and virulence of the Black Death from 1347 CE onwards, will be used as key examples of how climatic and environmental changes have, directly and/or indirectly, affected historical societies. Finally, I will prioritize future, interdisciplinary research avenues towards a better understanding of natural climate variations and its forcing agents, as well as the associated ecosystem responses and societal consequences throughout much of the late Holocene.

# Thursday 15th June 2017, 1.00pm - Carrie Andrew (Geography)
Brown Bag Discussion: Fungal Ecology and Global Change
Venue: Rm 101, William Hardy Building, Department of Geography, Downing Site

Carrie Andrew joined the Department as a visiting researcher at the start of Lent Term, collaborating with Prof. Ulf Büntgen. Carrie will be discussing her research looking at fungal ecology and global change.

# Thursday 1st June 2017, 1.00pm - Céline Vidal & Yves Moussallam (Geography)
Brown Bag Discussion: Tales from the Rift
Venue: Rm 101, William Hardy Building, Department of Geography, Downing Site

Céline Vidal and Yves Moussallam recently returned from fieldwork in Ethiopia and will introduce their research into volcanism in the Ethiopian Rift between 300,000 and 200,000 years ago, and it’s possible impacts on early antaomically-modern humans.

Bring your lunch!

# Thursday 18th May 2017, 4.00pm - Shaun Marcott, University of Wisconsin-Madison
The timing of cirque glaciation in western North America revisited: No Neoglacial in the U.S. Cordillera?
Venue: Castlereagh Room, Fisher Building, St John's College

Glaciers are intrinsically linked to climate, and given the sensitivity of small alpine glaciers to climate change, accurate and precise chronologies of their fluctuations are important in elucidating both the temporal and spatial structure of climate variability. Despite nearly a century of research, the timing of latest Pleistocene and Holocene alpine glaciation in much of western North America remains poorly constrained. I will present ~125 10Be ages from ~20 cirque moraines in 10 mountain ranges across western North America that were previously interpreted as mid- to late Holocene in age. Our new 10Be glacial chronology indicates that these moraines were deposited during the latest Pleistocene to earliest Holocene, requiring a refined interpretation of Holocene glacial activity in western North America and the associated climate forcing. Although alpine glaciers may have continued to fluctuate during the Holocene, they never advanced beyond their Little Ice Age maximum limit. Instead, cirque glacier activity in western North America has followed in near step with late Pleistocene high and mid latitude climate with alpine glaciers retreating to high altitude cirques early during the last deglaciation.

# Thursday 18th May 2017, 1.00pm - Michael Herzog (University of Cambridge)
Brown Bag Discussion: EGU Debrief
Venue: Rm 101, William Hardy Building, Department of Geography, Downing Site

“EGU Debrief” – Dr. Michael Herzog will chair a discussion of CED activities at this April’s EGU General Assembly. This will be an opportunity for members of the group to share the work presented at the conference.

As this is our first lunchtime discussion, lunch will be provided.

# Thursday 4th May 2017, 5.30pm - Chris Stokes, Durham University
How ice sheets collapse: a lesson from the Laurentide Ice Sheet
Venue: Cripps Auditorium, Cripps Court, Magdalene College

The contribution of the Greenland and West Antarctic ice sheets to sea level has increased in recent decades, largely due to the thinning and retreat of rapidly-flowing outlet glaciers and ice streams. This ‘dynamic’ loss is a serious concern, with some modelling studies suggesting that the collapse of a major ice sheet could be imminent or potentially underway in West Antarctica, but others predicting a more limited response. A major problem is that observations used to initialize and calibrate models typically span only a few decades and, at the ice-sheet scale, it is unclear how the entire drainage network of ice streams evolves over longer timescales. This represents one of the largest sources of uncertainty when predicting the contributions of ice sheets to sea-level rise. A key question is whether ice streams might increase and sustain rates of mass loss over centuries or millennia, beyond those expected for a given ocean–climate forcing. In this paper, we utilise a unique Quaternary record of 117 ice streams that operated at various times during deglaciation of the Laurentide Ice Sheet from about 22,000 to 7,000 years ago). We show that as they activated and deactivated in different locations, their overall number decreased, they occupied a progressively smaller percentage of the ice sheet perimeter and their total discharge decreased. The underlying geology and topography clearly influenced ice stream activity, but— at the ice-sheet scale—their drainage network adjusted and was strongly linked to changes in ice sheet volume. It is unclear whether these findings can be directly translated to modern ice sheets. However, contrary to the view that sees ice streams as unstable entities that can accelerate ice-sheet deglaciation, we conclude that ice streams exerted progressively less influence on ice sheet mass balance during the retreat of the Laurentide Ice Sheet.

# Thursday 9th March 2017, 5.30pm - Thomas Chalk, National Oceanography Centre, Southampton
Causes of ice-age intensification across the Mid-Pleistocene Transition, insights from a new boron isotope CO2 record
Venue: Latimer Room (Old Court), Clare College, Trinity Lane

During the Mid-Pleistocene Transition (MPT; 1200–800 thousand years ago, kyrs) Earth’s orbitally paced ice-age cycles intensified, lengthened from ~40 to ~100 kyrs, and became distinctly asymmetrical. Testing hypotheses that implicate changing atmospheric CO2 levels as a driver of the MPT has proven difficult with available observations. Here we use orbitally resolved, boron-isotope CO2 data to demonstrate that the glacial-to-interglacial CO2 difference increased from ~43 to ~75 µatm across the MPT, mainly due to lower CO2 levels during glacials. Through carbon-cycle modelling, we attribute this decline primarily to the initiation of substantive dust-borne iron fertilization of the Southern Ocean during peak glacial stages. We also observe a two-fold steepening of the relationship between sea level and CO2-related climate forcing that is suggestive of a change in the dynamics that govern ice-sheet stability, such as that expected from the removal of subglacial regolith. We argue that neither ice-sheet dynamics nor CO2 change in isolation can explain the MPT. Instead, we infer that the MPT initiated by a change in ice-sheet dynamics, and that longer and deeper post-MPT ice ages were sustained by carbon-cycle feedbacks related to dust fertilization of the Southern Ocean as a consequence of larger ice sheets.

This talk is part of the Quaternary Discussion Group (QDG).

# Thursday 23rd February 2017, 5.30pm - Francis Wenban-Smith, Archaeology, University of Southampton
MIS 7, the "Ebbsfleet Interglacial": sub-stage structure and recognition in the UK record
Venue: Latimer Room (Old Court), Clare College, Trinity Lane

More than 20 UK Quaternary sites are reliably related to MIS 7 of the global marine isotope stage framework. This interglacial has a distinctive O18:O16 profile of an early warm peak (MIS 7e) followed by a well-defined cooler episode (MIS 7d), which is followed in turn by a double warm peak (MIS 7c and MIS 7a) divided by a minor cool episode (MIS 7b). Foremost among UK MIS 7 sites is the Ebbsfleet Valley, a minor tributary on the south side of the Thames estuary. Here, approximately half a dozen separate localities have provided evidence of sequences from MIS 7, ranging from localities first investigated in the 1930s to currently-unpublished localities investigated as part of the HS1 archaeological programme. When the disparate palaeo-environmental, litho-stratigraphic and dating evidence from these Ebbsfleet localities is considered as a whole, a picture emerges in which all three warm MIS 7 peaks can be recognised and distinguished from each other, and their distinctive palaeo-environmental and biostratigraphic characteristics can thus provide the framework within which other UK sites should be integrated.

# Thursday 9th February 2017, 5.30pm - Paul Valdes, School of Geographical Sciences, University of Bristol
Modelling the Last Glacial-Interglacial Cycle: How sensitive are past climates?
Venue: Latimer Room (Old Court), Clare College, Trinity Lane

Understanding the mechanisms involved in Late Quaternary glacial cycles is one of the ultimate challenges for palaeoclimate science. The driving cause of the variability is related to changes in the Earth’s orbit but there are numerous feedbacks between the atmosphere, ocean, ice sheets and carbon cycle. Earth System Modelling can play an important role in quantifying some of these feedbacks and helping us to determine the major components of change. Through a combined modelling and data approach, palaeoclimate studies improve our understanding of key processes and hence contribute to improved confidence in future predictions. However, palaeoclimate studies have also attempted to directly estimate past climate sensitivity to CO2, a key parameter for future climate change. A key assumption of such work is that climate sensitivity is unchanging, so that knowing climate sensitivity in the past is relevant for climate sensitivity in the future. The talk will describe a series of modelling simulations that help us understand the feedback processes important during the last glacial-interglacial cycle, and show that the model relatively well represents the changes observed in the proxy climate data. We further use the model to investigate climate sensitivity. The simulations show that the sensitivity varies throughout the last 120,000 years, indicating that there are serious limitations on direct estimates of future climate sensitivity from palaeo-data.

This talk is part of the Quaternary Discussion Group (QDG)

# Thursday 26th January 2017, 5.30pm - Christine Lane, Department of Geography, University of Cambridge
Late Quaternary tephrostratigraphies from East African lakes
Venue: Latimer Room (Old Court), Clare College, Trinity Lane

This talk is part of the Quaternary Discussion Group (QDG)

Understanding the spatial and temporal variability of climate forcing and palaeoenvironmental response across a continent as climatically diverse as Africa relies upon comparison of data from widespread palaeoenvironmental archives. Accurate, precise and independent chronologies for such records are essential; however this remains a challenge in many environments and often prevents the valid comparison of detailed palaeo-proxy records. Many studies have now shown that volcanic ash (tephra) can be detected in terrestrial and marine sediments thousands of kilometres from their source, often as microscopic or “cryptic” layers. As well as offering opportunities for both direct (e.g. by 40Ar/39Ar methods) and indirect (e.g. by associated 14C dates) dating of the sediment sequence, tephra layers can provide stratigraphic tie-lines between archives, facilitating precise correlations at single moments in time. Furthermore, where two or more tephra layers are co-located in multiple records, rates of change can be compared within a period of equivalent duration, even in the absence of absolute age estimates.
Investigations into the presence of visible and non-visible (crypto-) tephra layers within lacustrine palaeoenvironmental records of the last ~150 ka BP from across East Africa are revealing the potential for this approach to (i) correlate palaeoclimate archives from across and beyond tropical Africa within a regional tephrostratigraphic framework; (ii) provide age constraints for individual core chronologies, in particular beyond the limits of radiocarbon dating; and (iii) increase our knowledge of the history of Late Quaternary explosive volcanism in East Africa.

# Thursday 24th November 2016, 5.30pm - Mick Frogley and Alex Chepstow-Lusty, University of Sussex
From Cambridge to Cuzco and back again: 4000 years of environmental history from the heart of the Inca Empire
Venue: Latimer Room (Old Court), Clare College, Trinity Lane

A sediment core brought back to Cambridge in 1993 from the small infilled lake of Marcacocha located at 3300 m above sea level in Andean Peru has provided a 4000-year record that, even today, continues to shed new light on environmental changes and how humans managed their environment. Surrounded by pre-Inca and Inca terraces and ruins, Marcacocha is located next to a major trade route that connects the Inca settlement of Ollantaytambo with the rainforest. By combining the study of conventional proxies such as pollen, dung fungal spores, plant macrofossils and sediment geochemistry with those that are less orthodox (such as oribatid mites), we have shown that the record spans the early development of agriculture and pastoralism, the rise and fall of the Inca Empire (c. AD 1400–1533) and into the historic period. Besides providing a detailed palaeoenvironmental record, there are indications that, particularly from 1000 years ago, major efforts in agroforestry and landscape stabilisation were being practiced. Indeed, these historic strategies may yet prove important in helping to alleviate the impacts of Peru’s increasingly acute water shortage issues, as Andean glaciers disappear and ancient aquifers are stressed by unregulated abstraction. This talk presents a welcome opportunity to bring the results of the project back to Cambridge after more than two decades.

# Thursday 10th November 2016, 5.30pm - Lucy Farr, University of Cambridge
Archaeological insights into the 8.2 ka event
Venue: Latimer Room (Old Court), Clare College, Trinity Lane

Greenland ice cores show a sharp decrease in oxygen isotope ratios and ice accumulation rates at 8.2 ka BP which persisted for c. 150 years (Dansgard et al., 1993; Grootes et al., 1993; Alley et al., 1997). Marine, ice and terrestrial proxy records from the Atlantic high and mid-latitudes, appear to consistently record a sharp change to colder, drier and possibly windier climatic conditions at this time (Pross et al., 2009).

The 8.2 ka event is a significant marker in palaeoclimatic studies, being identifiable in so many northern hemispheric records and recently posited as an official boundary marker dividing the Early and Mid-Holocene periods (Walker et al. 2012). Officially dividing the Holocene at the 8.2 ka event may be useful for archaeologists. Many archaeological records in Europe and south-west Asia show very clear technological, cultural and subsistence changes dating to the Early to Mid-Holocene transition, approximately 8000 years ago (e.g. Horn et al., 2015) but resolution issues frequently prohibit the identification of human responses in direct relation to the 8.2ka event. Recent advances in radiocarbon dating are now enabling archaeologists to better evaluate the role of the 8.2 ka event in cultural evolution occurring at this time (e.g. Flohr et al., 2016).

# Thursday 27th October 2016, 5.30pm - Jenny Collier, Imperial College London
The separation of Britain from mainland Europe in the late Quaternary
Venue: Latimer Room (Old Court), Clare College, Trinity Lane

It has been previously suggested that the separation of Britain from mainland Europe in the late Quaternary was a consequence of a catastrophic flood caused by a spillover of a proglacial lake that occupied the present-day southern North Sea basin during the Elsterian glaciation. Such an event would have significant palaeogeographic, biological and archaeological implications, but it remains controversial. Ten years ago we discovered a drainage system carved into the floor of the English Channel that is consistent with the catastrophic flood model. In this talk I will present a new compilation of seabed bathymetry and sub-bottom profiler data that we have used to analyse key landform features both within the downstream region and at the proposed breach point at the Straits of Dover. Our observations support the hypothesis that the landforms were initially carved by high-water volume flows via a unique catastrophic drainage of a pro-glacial lake in the southern North Sea at the Dover Strait rather than by fluvial erosion throughout the Pleistocene. The system also shows evidence for modification by a second flood that may have been a consequence of spillover of younger ice-marginal lake systems to the east, either in the North Sea basin or mainland Europe.

# Thursday 13th October 2016, 5.30pm - Kate Hendry, University of Bristol
Silicon cycling and opal production in the Atlantic: lessons from the last deglaciation
Venue: Latimer Room (Old Court), Clare College, Trinity Lane

Major shifts in ocean circulation are thought to be responsible for abrupt shifts in temperature and atmospheric CO2 as the Earth warmed up after the last ice age, linked to changes in latitudinal heat transport and deep ocean carbon storage. There is also widespread evidence for shifts in biological production during these times of deglacial CO2 rise, including enhanced growth of silica-producing algae (diatoms) in regions such as the equatorial Atlantic. In this talk, I’ll show how we can use marine sediment geochemical archives to demonstrate that the supply of dissolved silicon – a key nutrient for diatoms – was enhanced in the NE Atlantic during the abrupt climate events of the deglaciation. However, despite an enriched supply of this critical nutrient at depth, diatoms could only proliferate during abrupt climate shifts in regions of the NE Atlantic where the deep supply of dissolved silicon could reach the surface. These regions were influenced by enhanced regional wind-driven upwelling and weakened stratification due to circulation changes during phases of weakened Atlantic meridional overturning. Globally near-synchronous pulses of diatom production and enhanced subsurface concentrations of dissolved silicon suggest that widespread deglacial surface-driven breakdown of stratification, linked to changes in atmospheric circulation, had major consequences for biological productivity and carbon cycling across the North Atlantic.

# Thursday 12th May 2016, 5.30pm - Benjamin Stocker. Department of Life Sciences, Imperial College London
Large CO2 emissions from pre-industrial land use change – Does the carbon budget add up?
Venue: Thirkill Room, Clare College

CO2 emissions from preindustrial land use change (LUC) are subject to large uncertainties with model-based estimates ranging from 60 to 360 GtC (Olofsson and
Hickler, 2008; Pongratz et al., 2009; Kaplan et al., 2011; Stocker et al., 2011). Thus, early anthropogenic impacts rose to significance between 7-3 kyr BP depending on reconstruction and may have altered the natural carbon © cycle and climate states to a degree that would lend support for the definition of a correspondingly
early onset of the Anthropocene. However, the reconstructed parallel evolution of atmospheric CO2 and its 13C-signature indicate only 36+/-37 Gt loss of terrestrial C during the last 5 millennia (Elsig et al., 2009). It has been argued that this is the result of compensating effects of large LUC emissions and C sequestration in northern peatlands, which is estimated to be on the same order as upper-end estimates of
preindustrial LUC (Ruddiman and Ellis, 2009).

Here, we combine updated observation-based and model-based reconstructions of peat C buildup (∆Cpeat) and model-based LUC emission estimates for a range of
recently published reconstructions (Kaplan et al., 2009; Klein Goldewijk and Verburg, 2013) and accounting for changing land management regimes over time and space.
Using the independent constraint on the total terrestrial C budget from ice core measurements of CO2 and d13C (∆Ctot), we assess the compatibility of different LUC
scenarios with ∆Ctot and ∆Cpeat.

This reveals that large LUC emissions required to explain the observed CO2 rise between 7 and 5 kyr BP cannot be reconciled with ∆Ctot and ∆Cpeat unless a large additional terrestrial sink is invoked. Furthermore, this analysis points to the importance of other, non-anthropogenic impacts for explaining the ~150 Gt terrestrial C source between 5 and 2 kyr BP, where scenarios suggest emissions of only 20-50 GtC. More highly resolved ice core (Bauska et al., 2015) and peat C balance data (Charman et al., 2013) covering the last millennium further reveals that only extreme assumptions on the extent of post-Columbian reforestation in the Americas can close the C budget between 1500 and 1650 CE and that upper-end scenarios of preindustrial LUC are incompatible with the C budget between 1760 and 1920 CE.

# Thursday 5th May 2016, 5.30pm - Mike Walker, School of Archaeology, History & Anthropology, Trinity Saint David, University of Wales, Lampeter, and Department of Geography and Earth Sciences, Aberystwyth University
A formal subdivision of the Holocene Series/Epoch
Venue: Thirkill Room, Clare College

This presentation considers the prospects for a formal subdivision of the Holocene Series/Epoch. Although previous attempts to subdivide the Holocene have proved inconclusive, recent developments in Quaternary stratigraphy, including the definition of the Pleistocene–Holocene boundary and subdivisions of the Pleistocene Series/Epoch, mean that it may be timely to revisit this matter. The Quaternary literature reveals a widespread, but variable, informal usage of a tripartite division of the Holocene (‘Early’, ‘Middle’ or ‘Mid’, and ‘Late’), and it is suggested that this de facto subdivision should now be formalized to ensure consistency in stratigraphic terminology. The proposal is for three stages and subseries/subepochs of the Holocene: the Greenlandian, Northgrippian and Meghalayan, each of which is underpinned by a Global Standard Stratotype Section and Point (GSSP). It is suggested that the Early–Middle Holocene boundary should be defined by the global cooling event at 8.2 ka BP, and the Middle–Late Holocene boundary by the widespread low-latitude aridity phase at 4.2 ka BP, Should the proposal find support from the Quaternary community, a submission for ratification will be made to the International Union of Geological Sciences (IUGS), via the Subcommission on Quaternary Stratigraphy (SQS) and the International Commission on Stratigraphy (ICS).

# Thursday 21st April 2016, 5.30pm - Maryline Vautravers (University of Cambridge)
1 million years of Pacific Ocean paleoceanography viewed from IODP Exp350 sites 1436C and 1437B foraminifers' records recovered near the IZU subduction Arc
Venue: Thirkill Room, Clare College

In 2014 I sailed for 2 months on IODP EXP350 on board JOIDES Resolution, South of Japan near the Izu-Arc formed by the subduction of the West Pacific plate under the Phillippine plate. The area investigated near 30° N is affected by the Kuroshio Current. The age models for 2 Sites; U1436C and U1437B are based on stable isotopes stratigraphy N. dutertrei. The quantitative micropaleontological (planktonic foraminifer) content for 460 samples includes the indices of calcium carbonate preservation, individual shell weight, percent planktonic foraminifer fragments, planktonic foraminifer concentrations, various faunal proxies, and benthic/planktonic ratio. Altogether evidencing qualitative surface temperatures changes traced by faunal polar/subpolar versus subtropical assemblages recording the changing influences in the Kuroshio/Oyashio currents over the last 1 My. The remarkable locations of the sites at intermediate water depth in the Pacific Ocean; but separated by the hydrographic divide created by the Izu rise provide a rare insight opportunity into the operation of intermediate circulations and the influence of Quaternary Northern Hemisphere glaciations on the operation of the intermediate water mass as can be traced by changes in carbonates preservation recorded by foraminifers. The study points to the so-called Pacific carbonate cycles pattern recorded in the NW Pacific at intermediate depth to be the result of climatological and/or geochemical changes originating in the North Atlantic affecting the NADW production during interglacials and the NAGW during glacials. In term of paleoceanographic/climatic evolution it also points at MIS17 as a remarkable interglacial within the Pacific Ocean realm.

# Thursday 10th March 2016, 5.30pm - James Scourse (Bangor University)
North Atlantic annually resolved temperatures for the last millennium: the Arctica islandica record.
Venue: Latimer Room, Clare College

Abstract not available

# Thursday 25th February 2016, 5.30pm - Michael Weber (Institute of Geology and Mineralogy, University of Cologne)
Ice sheet, atmosphere, and ocean dynamics in the Atlantic sector of Antarctica – past reconstruction and future course.
Venue: Latimer Room, Clare College

Abstract not available

# Thursday 11th February 2016, 5.30pm - Eric Galbraith (ICREA, Barcelona, Spain),
Orbital wobbles, ice sheets, CO2, and the deep sea: a model-informed perspective on the ocean’s role in Quaternary climate.
Venue: Cripps Meeting Room 5, Cripps Court Building, Chesterton Road, Magdalene College

Abstract not available

# Thursday 3rd December 2015, 5.30pm - Sebastian Breitenbacher (Earth Sciences Department, University of Cambridge)
Climate and Society: Examples of the climate impact on civilizations
Venue: Latimer Room, Clare College

Abstract not available

# Thursday 19th November 2015, 5.30pm - Mark Bateman (Department of Geography, University of Sheffield)
Using the Land-Ocean Transition to understand coastal landscapes
Venue: Latimer Room, Clare College

Abstract not available

# Thursday 5th November 2015, 5.30pm - Christopher Evans (Division of Archaeology, University of Cambridge)
Landscape Retreat and 'Jumping': Late Prehistoric Fenland Environmental Adaption/Response
Venue: Latimer Room, Clare College

Abstract not available

# Thursday 15th October 2015, 5.30pm - Anais Orsi, Laboratoire des Sciences du Climat et de l'Environnement, Gif-sur-Yvette (France)
The last 1000 years in East Antarctica: insights from a new temperature proxy.
Venue: Cripps Meeting Room 4, Cripps Court Building, Chesterton Road, Magdalene College

Abstract not available

# Thursday 28th May 2015, 5.30pm - Prof Dr. Dominik Fleitmann (University of Reading)
Stalagmites as excellent recorders of major volcanic eruptions
Venue: Cripps Meeting Room 3, Cripps Court Building, Chesterton Road, Magdalene College

Abstract not available

# Thursday 14th May 2015, 5.30pm - Dr. Sambuddha Misra (Godwin Laboratory for Palaeoclimate Research, Earth Sciences Department, University of Cambridge)
Boron isotopes as pH proxy: a critical evaluation
Venue: Cripps Meeting Room 3, Cripps Court Building, Chesterton Road, Magdalene College

Abstract not available

# Thursday 5th March 2015, 5.30pm - Prof Chris D. Clark, Department of Geography, University of Sheffield (UK)
Retreat of the last British-Irish Ice Sheet; landforms, sediments, dates and the BRITICE-CHRONO project
Venue: Thirkill Room, Clare College

Abstract not available

# Thursday 19th February 2015, 5.30pm - Prof Mary E. Edwards, Department of Geography and Environment, University of Southampton (UK)
New DNA approaches to understanding Late-Quaternary and recent biodiversity changes – potential and problems
Venue: Thirkill Room, Clare College

Major advances in the ability to sequence many DNA samples has led to a proliferation of Quaternary molecular studies. The Ecochange project developed a methodology that allows DNA of vascular plants and mammals to be extracted from Quaternary sediments and used as proxy data for the components of terrestrial ecosystems. It uses an approach called “metabarcoding”: for plants, this is based on short (10-200 BP) sequences of chloroplast or nuclear DNA. Taxonomic resolution is potentially better than that of pollen and matches that of macrofossils. Furthermore, DNA detects the presence of taxa at when biomass levels are relatively low. I will illustrate the current status of DNA-based palaeoecological reconstructions with a range of modern (calibration) and fossil studies from Siberian yedoma, northern lake sediments (from Svalbard and Scotland) and modern tundra landscapes. Key findings are that modern soil DNA matches the taxa present in modern vegetation with few false positives and roughly reflects biomass, that DNA in lakes does not seem to reflect pollen when there is no vegetative biomass in the catchment, that forb taxa were a surprisingly large component of glacial-age vegetation across unglaciated Eurasia, and that the Holocene DNA record from Svalbard shows rapid early colonization and resilience of the flora in the face of climatic deterioration. New and stricter protocols for sequencing and bioinformatics filtering are improving the ability to determine false positives in the data, which were likely a problem in the first, pioneering studies.

# Thursday 29th January 2015, 5.30pm - Dr. Heather Ford (Lamont Doherty Earth Observatory, Columbia University)
El Niño and El Padre: a deep equatorial Pacific thermocline during the Pliocene warm period
Venue: Cripps Meeting Room 4, Cripps Court Building, Chesterton Road, Magdalene College

Abstract not available

# Thursday 15th January 2015, 5.30pm - Prof Eric J. Steig, Department of Earth and Space Sciences, University of Washington (US)
The role of the ocean and the atmosphere in the expression of D-O and AIM events in Antarctica: new evidence from the WAIS Divide Ice Core
Venue: Cripps Meeting Room 4, Cripps Court Building, Chesterton Road, Magdalene College

Abstract not available

# Thursday 4th December 2014, 5.30pm - Dr Peter Abbott (University of Swansea)
Cryptotephrochronology in the North Atlantic Region: Linking North Atlantic Marine Sediments to the Greenland ice-cores
Venue: Thirkill Room, Clare College

Tephrochronology is a powerful technique that can be utilised for the correlation and synchronisation of disparate palaeoclimatic records from different depositional
environments. Thus, this technique has considerable potential for addressing key questions relating to rapid climatic events that characterised the last glacial period. In particular, our search for microscopic tephra layers or cryptotephras within the Greenland ice-cores and marine cores from the North Atlantic Ocean has the potential to test the phase relationships between the atmospheric and oceanic responses to these high-magnitude and abrupt climatic events.
Tephrochronological investigations are currently being undertaken on a network of marine cores from a range of locations and depositional settings within the North Atlantic as part of the ERC-funded project Tephra constraints on Rapid Climate Events (TRACE). Tephra horizons have been identified in the marine records through the successful use of cryptotephra extraction techniques more commonly applied to the study of terrestrial sequences. The two main challenges associated with cryptotephra work in the glacial North Atlantic are i) determining the dominant transportation processes and ii) assessing the influence of secondary reworking processes and the integrity of the isochrons. The potential influence of these processes is investigated by assessing shard size, geochemical (major and trace element) heterogeneity and co-variance of IRD input for some cores. We are also applying the innovative techniques of micromorphology and X-ray tomography to the study of these processes.
Early comparison of the tephrochronological record of cores within the network highlight a number of potential marine to ice linkages and the potential for these to allow an assessment of the relative timing of climatic changes between the ocean and atmosphere will be discussed.

# Friday 14th November 2014, 5.30pm - Dr Lauren Gregoire (School of Earth and Environment, University of Leeds)
The North American deglaciation: linking rapid climate change, ice sheet retreat and sea level rises
Venue: Latimer Room, Clare College

The last deglaciation (approx. 21-7ka) was punctuated by several abrupt climatic and sea level changes in which ice sheets are thought to have played an important role.
This talk describes the role of the N. American ice sheet in two of the most important event of rapid sea level change:
(i) the MWP-1a, a ~ 14-18 m global sea level rise in less than 350 years which coincided with the rapid N. Hemisphere Bolling warming;
(ii) the ‘8.2 kyr event’, a century long cooling event attributed to the sudden release of N. American glacial lakes.
By combining, climate, ice sheet and sea level modelling with a variety of palaeo-environment data I evaluate (i) the mechanisms that lead to accelerated ice melt and (ii) the impacts of these on the climate. I will present recent efforts to constrain the contribution of the N. American ice sheet to MWP1a from the Bolling warming and a mass balance mechanism named the saddle collapse. Finally, I will introduce the recent plans of the Palaeo Model Intercomparison Project for simulating the climate of the last deglaciation.

# Thursday 6th November 2014, 5.30pm - Prof Dr Hubertus Fischer (Oeschger Centre for Climate Change Research, University of Bern)
Changes in the Global Carbon Cycle over the last 800,000 years - an ice core perspective
Venue: Thirkill Room, Clare College

Abstract not available

# Wednesday 22nd October 2014, 4.00pm - Prof Bill Ruddiman (Department of Environmental Sciences, University of Virginia, US)
Top-down and bottom-up evidence for the early anthropogenic hypothesis
Venue: Tilley Lecture Theatre, Department of Earth Sciences, Downing Street

Abstract not available

# Monday 7th July 2014, 5.00pm - Professor Richard Alley, Evan Pugh Professor of Geoscience, Penn State University, USA
People should be aware that 7th July is Tour de France day, but we hope things will have become accessible by 5.00 pm.
Fracking the fjords: Earthquakes and glacial erosion, with some additional thoughts about stability of the West Antarctic Ice Sheet
Venue: Tilley Lecture Theatre, Department of Earth Sciences

Abstract not available

# Wednesday 27th November 2013, 5.00pm - Dr. Patrick Grunert (U. of Graz, Austria)
CHANGE OF DATE: now on Wednesday Nov. 27th
Benthic foraminiferal assemblages as proxies of paleoceanographic changes across Pleistocene glacial terminations in the NE Atlantic
Venue: Thirkill Room, Clare College

The study of fossil foraminifera goes back to the early 19th century, making them one of the best studied microfossil groups. More recently, our increasing understanding of their distribution and ecological requirements in the present-day oceans has made the quantitative evaluation of foraminiferal assemblages a powerful means of actualistic paleoenvironmental reconstruction.
In this paper I present examples for the application of benthic foraminiferal assemblages from IODP Site U1385 (“Shackleton Site”) as proxies of paleoceanographic Change in the Pleistocene NE Atlantic. A brief introduction to the present-day distribution of benthic foraminifera in the area and the relation to the oceanographic setting is followed by an evaluation of differences between the present-day situation and major glacial/interglacial transitions. The presentation is wrapped up by a discussion of the implications of observed turnovers in the benthic foraminiferal fauna for changes of sea-water properties at the water/sediment interface during these rapid climatic transitions.

# Thursday 7th November 2013, 5.00pm - Prof. Eric Wolff (Dept. of Earth Sciences, Cambridge)
Interglacials of the last 800,000 years
Venue: Thirkill Room, Clare College

Abstract not available

# Thursday 24th October 2013, 4.00pm - Prof. Howard J. Spero (University of California)
Note unusual time
The paleoceanography frontier: proxies, new technologies and novel questions
Venue: Latimer Room, Clare College

Please note different time and venue: Latimer Room, 4pm

In recent years, new geochemical proxies and emerging technologies have been combined to explore novel paleoclimatic questions that were only dreamed about a decade ago. In this presentation I will discuss how the application of new technologies such as laser ablation ICP-MS (e.g. Mg/Ca, Ba/Ca), SIMS (e.g. d18O, d13C) and nanoSIMS can be used to address old and new paleoceanographic problems. I will present data from laboratory experiments with living planktonic foraminifera that have allowed us to calibrate these proxies and reduce the spatial resolution of geochemical analyses to the micron and sub-micron level. These data confirm many of the fundamental geochemical relationships used by researchers to reconstruct ocean temperatures and water geochemistry from the fossil record. When individual foraminifera from a fossil assemblage are analyzed using LA-ICP-MS (Mg/Ca, Ba/Ca) and coupled to d18O measurements from standard isotope ratios mass spectrometry (IRMS), we may be able to extract novel information from the fossil record that was not previously possible. I will present data collected at the interface of these two geochemical technologies that has allowed us to calculate the oxygen isotopic composition of Laurentide Ice Sheet meltwater during the last deglaciation.

# Thursday 17th October 2013, 5.00pm - Dr. Maryline Vautravers (Cambridge)
Canceled
Taking a closer look at the last glacial sediments
Venue: Thirkill Room, Clare College

Abstract not available

# Thursday 14th March 2013, 5.15pm - Dr. Katy Pol (British Antarctic Survey)
Evidence for enhanced Antarctic climate variability during the last interglacial period
Venue: Thirkill Room, Clare College

Abstract not available

# Thursday 21st February 2013, 5.00pm - Prof. James Rose (Dept. of Geography, Royal Holloway U. of London)
The Bytham river story - key evidence for understanding pre-glacial environmental change and early human occupance in Britain
Venue: Thirkill Room, Clare College

A special double session on the Bytham river!

# Thursday 21st February 2013, 5.00pm - Prof. Philip Gibbard (Dept. of Geography, U. of Cambridge)
Testing the Bytham river hypothesis
Venue: Thirkill Room, Clare College

A special double session on the Bytham river!

# Thursday 7th February 2013, 5.00pm - Prof. Liping Zhou (Peking University, China)
Late Quaternary loess records from northern China and central Asia: implications for variations in monsoon and westerly circulation
Venue: Thirkill Room, Clare College

Abstract not available

# Thursday 24th January 2013, 5.00pm - Prof. Graeme Barker (McDonald Institute of Archaeological Research, U. of Cambridge)
Modern human adaptations to Pleistocene rainforest: the archaeology of the Niah Caves, Sarawak, Borneo
Venue: Thirkill Room, Clare College

Abstract not available

# Thursday 10th January 2013, 5.00pm - Dr. David Thornalley (Woods Hole Oceanographic Institution, USA)
The release of d14 C and d18 O-depleted water from the Arctic Ocean upon glacial termination
Venue: Thirkill Room, Clare College

Abstract not available

# Friday 30th November 2012, 5.00pm - Dr Anna-Lena Grauel (Dept. of Earth Sciences, Cambridge)
New estimates of tropical ice age temperature
Venue: Thirkill Room, Clare College

Abstract not available

# Friday 23rd November 2012, 5.00pm - Dr Emilie Capron (BAS)
Please note change of speaker
Using nitrogen isotopes to constrain the age of the air extracted from antarctic ice cores
Venue: Thirkill Room, Clare College

Abstract not available

# Friday 9th November 2012, 5.00pm - Dr Aline Govin (MARUM, Bremen)
Precipitation changes in the Amazon Basin during the last 240 ka
Venue: Thirkill Room, Clare College

Abstract not available

# Friday 26th October 2012, 5.00pm - Dr David Wilson (Dept. of Earth Sciences, Cambridge)
Decoupled ocean circulation and carbon cycling during glaciations: Implications for the dynamics of glacial cycles
Venue: Thirkill Room, Clare College

Abstract not available

# Friday 18th May 2012, 5.00pm - Dr Natalia Vazquez-Riveiros (Earth Sciences, University of Cambridge)
Carbon isotopes and glacial-interglacial CO2: the curious case of Marine Isotope Stage 12
Venue: Thirkill Room, Clare College

Abstract not available

# Friday 11th May 2012, 5.00pm - Prof. Martin Jones (Archaeology, University of Cambridge)
The Moravian Gate project: new insights into the human food quest in Stage 3 Central Europe
Venue: Thirkill Room, Clare College

Abstract not available

# Friday 4th May 2012, 5.00pm - Dr Luke Skinner (Earth Sciences, University of Cambridge
A bipolar seesaw in Atlantic deep-water ventilation: Wally was right
Venue: Thirkill Room, Clare College

Due to the absence of key individuals this week, there has been a change to the topic of the seminar scheduled.

# Friday 27th April 2012, 5.00pm - Prof. Hema Achyuthan (Anna University, Chennai)
Quaternary palaeoclimate changes from the margins of the Indian Thar Desert
Venue: Thirkill Room, Clare College

Abstract not available

# Friday 24th February 2012, 5.00pm - Prof. Veli-Pekka Salonen (Dept. of Geosciences and Geography, University of Helsinki, and Visiting fellow at Clare Hall)
Lessons from the High Arctic: new results from late Quaternary studies in Nordaustlandet, Svalbard
Venue: Thirkill Room, Clare College

Abstract not available

# Friday 20th January 2012, 5.00pm - Kate Darling (University of Edinburgh)
Genetic diversity, global phylogeography and seasonality of the planktonic foraminifera G. bulloides: implication for palaeoproxies
Venue: Thirkill Room, Clare College

Abstract not available

# Friday 2nd December 2011, 5.00pm - Dr Aleksey Sadekov (Department of Earth Sciences, Cambridge)
Role of the Tropical Pacific in Millennial-Scale Climate Events
Venue: Seminar Room 3, Cripps Court, Magdalene College

IMPORTANT: In order to avoid conflict with the new CCfCS seminar series held on on Thursdays, we have had to reschedule these QDGs to Fridays and host them in MAGDALENE COLLEGE. The seminars will take place in CRIPPS COURT in Meeting Room 3. Cripps Court is opposite Magdalene College on Chesterton Road (http://conference.magd.cam.ac.uk/find-us). The room will be signposted to help you find us.

As usual, wine and discussion will follow the seminars.

# Friday 18th November 2011, 5.00pm - Outi Hyttinen (Department of Geosciences and Geography, University of Helsinki, FInland)
Traces of the Baltic Ice Lake drainage in the northern Baltic Sea and southern Finland
Venue: Seminar Room 3, Cripps Court, Magdalene College

IMPORTANT: In order to avoid conflict with the new CCfCS seminar series held on on Thursdays, we have had to reschedule these QDGs to Fridays and host them in MAGDALENE COLLEGE. The seminars will take place in CRIPPS COURT in Meeting Room 3. Cripps Court is opposite Magdalene College on Chesterton Road (http://conference.magd.cam.ac.uk/find-us). The room will be signposted to help you find us.

As usual, wine and discussion will follow the seminars.

# Friday 4th November 2011, 5.00pm - Professor Harry Elderfield (Department of Earth Sciences, Cambridge)
Evolution of ocean temperature and ice volume from the Mid Pleistocene Climate Transition
Venue: Thirkill Room, Clare College

Abstract not available

# Wednesday 26th October 2011, 5.00pm - Dr Ian Bailey (School of Ocean & Earth Science, National Oceanography Centre Southampton)
New insights on old questions concerning Quaternary northern hemisphere glaciation
Venue: Thirkill Room, Clare College

Abstract not available

# Tuesday 31st May 2011, 5.00pm - Dr Axel TImmermann (SOEST, University of Hawai'i, USA); Dr Jess Adkins (CALTECH, USA)
A special set of QDG talks
Venue: Latimer Room, Clare College

5:00 pm – Dr Axel TImmermann (SOEST, University of Hawai’i, USA): ‘Understanding orbitally-driven climate change in the Southern Hemisphere’

5:45 pm – Discussion, wine and finger food

6:00 – Dr Jess Adkins (CALTECH, USA):
‘The deep ocean’s role in glacial-interglacial cycles’.

6:45 – Discussion, and more wine!

All are welcome; you may not get another chance to hear how the Southern Hemisphere and the deep ocean both control global glacial-interglacial climate change, in one sitting!

# Thursday 19th May 2011, 5.00pm - Martin Ziegler, Cardiff University
Orbital forcing of Late Pleistocene climate variability - From the global monsoon to glacial terminations
Venue: Thirkill Room, Clare College

Abstract not available

# Thursday 28th April 2011, 5.00pm - Dr Samuel Toucanne (IFREMER, France)
Pleistocene Fleuve Manche palaeoriver discharges : Response to glacial oscillations and climate changes
Venue: Latimer Room, Clare College

Abstract not available

# Friday 18th February 2011, 5.00pm - Dr Phillip Hughes, The University of Manchester
Quaternary glaciation in the Mediterranean mountains: new results from North Africa and the Balkans
Venue: Thirkill Room, Clare College

Abstract not available

# Friday 11th June 2010, 5.00pm - Richard West (Professor emeritus, Cambridge University, Clare College)
The History of Quaternary Research at Cambridge University
Venue: Thirkill Room, Clare College

Abstract not available

# Friday 13th February 2009, 5.15pm - Steven Pawley (Royal Holloway, University of London)
Canceled
Glacial Chronologies Spanning the Past 450 ka Around the Margins of the Southern North Sea and implications for the age of the Strait of Dover
Venue: Lloyd Room, Christ's College

Abstract not available

# Friday 30th January 2009, 5.15pm - Peter Koehler (Alfred Wegener Institute, Germany)
The carbon cycle during the Pleistocene
Venue: Lloyd Room, Christ's College

Abstract not available

# Friday 23rd January 2009, 5.15pm - Anne Osborne (Bristol University)
A humid corridor across the Sahara for the migration "Out of Africa" of early modern humans 120,000 years ago.
Venue: Lloyd Room, Christ's College

Abstract not available