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The Godwin Laboratory for Palaeoclimate Research

 

Wed 22 May 14:00: Whole Earth oscillations: Thé key to imaging Earth’s deep interior

http://talks.cam.ac.uk/show/rss/15125 - Fri, 17/05/2024 - 21:33
Whole Earth oscillations: Thé key to imaging Earth’s deep interior

Tectonic processes at Earth’s surface, are driven by convection deep in Earth’s mantle. Seismic tomography using earthquakes is the main tool to directly image the lower mantle. Such images show two large continental size regions just above the core mantle boundary, one located under the Pacific and the other one under Africa. These two regions have low shear wave velocity, but their role in mantle convection as either a thermal plume or a stable compositional pile is still heavily debated. Here, I will show that the key to unravelling the nature of these two regions are whole Earth oscillations. These normal modes do not only provide shear wave velocity, but also additional information such as their density and attenuation. We find that the low velocity regions are partially dense at their base and have weak attenuation, requiring puzzling new interpretations in terms of mantle dynamics.

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Thu 23 May 11:30: Some aspects of contact line dynamics with applications to flow in porous materials

http://talks.cam.ac.uk/show/rss/15125 - Thu, 16/05/2024 - 09:20
Some aspects of contact line dynamics with applications to flow in porous materials

Among the most difficult issues in CFD is the very wide range of scales involved in some problems. Attempts at investigating the dynamics contact line have been made coming from various theoretical and numerical frameworks, the closest to first principles being molecular dynamics, while diffuse interface methods and sharp interface methods with several variants have also been put forward. Experiments are obviously difficult. Efforts made on a number of typical cases, including plunging and withdrawing plates, a sheared droplet, sessile droplets on oscillating or accelerating substrates, menisci in nanopores and the hydrodynamics assist problem. The issues involved in nucleate boiling and accelerated sessile droplets will be addressed both from the point of view of experiments (performed by various colleagues from MIT and Tokyo University) and from the point of view of simulations.

I will also show recent developments in the Basilisk code allowing to simulate contact lines on complex curved boundaries, using the immersed boundary method and an appropriate contact angle boundary condition, and inside porous media.

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Tue 28 May 12:00: Towards a 500 Million-Year History of Earth’s Atmospheric CO2

http://talks.cam.ac.uk/show/rss/15125 - Wed, 15/05/2024 - 13:10
Towards a 500 Million-Year History of Earth’s Atmospheric CO2

Earth’s atmospheric CO2 concentration for the Phanerozoic Eon (the last 540 million years) has been estimated from proxies and models with varying degrees of success, resulting in considerable discrepancies between estimates. Recent advances in applying boron isotopes to foraminifera have revolutionised our understanding of Cenozoic CO2 levels (the last 66 million years) leading to a growing consensus for Earth’s more recent history. However, questions remain about the limitations of the boron isotope proxy as dependent on the extent of preservation of marine sediments and, consequently, deep-time boron-based reconstructions from Earth’s rock record have been regarded as controversial. In this talk, I will make the case that the boron isotope composition of well-preserved brachiopod shells provides a robust tool for extending our knowledge of CO2 throughout the Phanerozoic, and by showcasing new Mesozoic and Palaeozoic records I will review the role of CO2 in Earth’s major climate transitions and mass extinction events.

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Tue 28 May 12:00: Towards Robust Reconstruction of Phanerozoic Atmospheric CO2 Levels

http://talks.cam.ac.uk/show/rss/15125 - Wed, 15/05/2024 - 09:57
Towards Robust Reconstruction of Phanerozoic Atmospheric CO2 Levels

Earth’s atmospheric CO2 concentration for the Phanerozoic Eon (the last 540 million years) has been estimated from proxies and models with varying degrees of success, often resulting in considerable discrepancies between estimates. Recent advances in the applying boron isotopes to foraminifera have revolutionised understanding of Cenozoic CO2 levels (the last 66 million years), although gaps still exist. However, questions remain about the limitations of the boron isotope proxy as dependent on the extent of preservation of marine sediments and, consequently, deep time boron-based reconstructions from Earth’s rock record have been regarded as controversial. In this talk, I will make the case that the boron isotope composition of well-preserved brachiopod shells provides a robust tool for extending our knowledge of CO2 throughout the Phanerozoic, and by showcasing new Mesozoic and Palaeozoic records I will review the role of CO2 in Earth’s major climate transitions and mass extinction events.

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Wed 15 May 14:00: The Turkana Rift Arrays Investigating Lithospheric Structure (TRAILS) Experiment

http://talks.cam.ac.uk/show/rss/15125 - Tue, 14/05/2024 - 11:34
The Turkana Rift Arrays Investigating Lithospheric Structure (TRAILS) Experiment

The Turkana Depression is a broad, topographically-subdued, region between the elevated Ethiopian and East African Plateaus. The Depression is unique in East Africa for being host to a NW-SE-trending failed Mesozoic (Anza) rift system through which the near-orthogonal, N-S-trending East African Rift subsequently developed. Whether the Depression’s low-lying nature is a result of a significantly thinned crust instigated by its multiple rifting phases, or instead due to a lack of dynamic mantle support is debated. Also poorly understood is the extent to which Cenozoic rifting and magmatism have developed across the Depression during the linkage of other comparatively narrow East African Rift zones to the north and south. Utilising data from the 2019-2021 Turkana Rift Arrays Investigating Lithospheric Structure project and surrounding networks, receiver function analysis and its joint inversion with surface-waves, are used to probe Moho architecture and the lithosphere-asthenosphere system.

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Thu 09 May 11:30: Engineering solutions for heart valve disease using computational modelling and simulation

http://talks.cam.ac.uk/show/rss/15125 - Wed, 08/05/2024 - 09:01
Engineering solutions for heart valve disease using computational modelling and simulation

Transcatheter valve replacement is a revolutionary, minimally invasive alternative to surgery for patients with heart valve disease. With over 1.5 million procedures performed worldwide and expectations of a sharp increase in the coming years, there is growing concerns about the rise in adverse events such as coronary obstruction and valve thrombosis. It is anticipated that the interaction between the implanted transcatheter heart valve with patient-specific anatomy may give rise to unfavourable hemodynamics, contributing to these adverse events. In this seminar, we will explore the role of computational modelling and simulation in improving our mechanistic understanding of these events, and as a tool to assist clinicians in patient selection and pre-procedural planning, ultimately improving patient outcomes.

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Wed 05 Jun 17:30: Extreme glacial implies discontinuity of early human occupation of Europe Building doors are card operated, so latecomers may not be able to access the venue.

http://talks.cam.ac.uk/show/rss/17246 - Wed, 01/05/2024 - 21:50
Extreme glacial implies discontinuity of early human occupation of Europe

The oldest known hominin remains in Europe [ca. 1.5 to 1.1 million years ago (Ma)] have been recovered from Iberia, where paleoenvironmental reconstructions have indicated warm and wet interglacials and mild glacials, supporting the view that once established, hominin populations persisted continuously. We report analyses of marine and terrestrial proxies from a deep-sea core on the Portugese margin that show the presence of pronounced millennial-scale climate variability during a glacial period ca. 1.154 to 1.123 Ma, culminating in a terminal stadial cooling comparable to the most extreme events of the last 400,000 years. Climate envelope–model simulations reveal a drastic decrease in early hominin habitat suitability around the Mediterranean during the terminal stadial. We suggest that these extreme conditions led to the depopulation of Europe, perhaps lasting for several successive glacial-interglacial cycles.

Building doors are card operated, so latecomers may not be able to access the venue.

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Wed 05 Jun 17:30: Extreme glacial implies discontinuity of early human occupation of Europe Building doors are card operated, so latecomers may not be able to access the venue.

http://talks.cam.ac.uk/show/rss/15125 - Wed, 01/05/2024 - 21:50
Extreme glacial implies discontinuity of early human occupation of Europe

The oldest known hominin remains in Europe [ca. 1.5 to 1.1 million years ago (Ma)] have been recovered from Iberia, where paleoenvironmental reconstructions have indicated warm and wet interglacials and mild glacials, supporting the view that once established, hominin populations persisted continuously. We report analyses of marine and terrestrial proxies from a deep-sea core on the Portugese margin that show the presence of pronounced millennial-scale climate variability during a glacial period ca. 1.154 to 1.123 Ma, culminating in a terminal stadial cooling comparable to the most extreme events of the last 400,000 years. Climate envelope–model simulations reveal a drastic decrease in early hominin habitat suitability around the Mediterranean during the terminal stadial. We suggest that these extreme conditions led to the depopulation of Europe, perhaps lasting for several successive glacial-interglacial cycles.

Building doors are card operated, so latecomers may not be able to access the venue.

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Wed 08 May 14:00: Searching for habitability on Venus and exoplanets

http://talks.cam.ac.uk/show/rss/15125 - Tue, 30/04/2024 - 11:59
Searching for habitability on Venus and exoplanets

Venus today presents a type example of how habitability can fail to persist on a planet: rocky and to a first order overwhelmingly Earth-like, but with a climate profoundly hostile to life’s complex molecular machinery. But, was it always like this and will we know a Venus from an Earth when we see one elsewhere in the galaxy? This talk investigates what evidence there may be to constrain Venus’s past climate state, and relates this to the frontier of our search for habitable conditions on exoplanets.

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Wed 16 Oct 14:00: Title to be confirmed

http://talks.cam.ac.uk/show/rss/15125 - Tue, 30/04/2024 - 11:50
Title to be confirmed

Abstract not available

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Wed 01 May 14:00: New Insights from the Collaboratory for the Study of Earthquake Predictability (CSEP)

http://talks.cam.ac.uk/show/rss/15125 - Sun, 28/04/2024 - 11:23
New Insights from the Collaboratory for the Study of Earthquake Predictability (CSEP)

As seismology enters the era of statistical aftershock forecasting and continuous real-time seismic hazard estimation, the community needs independent model evaluation methodology to provide the best available science and to understand its current limitations. CSEP is a global community with a mission to improve earthquake forecasting by comparative model testing in a truly prospective manner (i.e., against data not yet available during model development). In this talk, I will provide an overview of new insights into earthquake predictability gained by CSEP experiments around the globe and over nearly two decades. I will illustrate how these insights are informing national seismic hazard models and real-time forecasting.

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Wed 29 May 14:00: Title to be confirmed

http://talks.cam.ac.uk/show/rss/15125 - Thu, 25/04/2024 - 15:12
Title to be confirmed

Abstract not available

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Wed 29 May 14:00: Title to be confirmed

http://talks.cam.ac.uk/show/rss/15125 - Thu, 25/04/2024 - 14:22
Title to be confirmed

Abstract not available

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Wed 12 Jun 14:00: Title to be confirmed

http://talks.cam.ac.uk/show/rss/15125 - Thu, 25/04/2024 - 14:20
Title to be confirmed

Abstract not available

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Wed 05 Jun 14:00: Title to be confirmed

http://talks.cam.ac.uk/show/rss/15125 - Thu, 25/04/2024 - 14:19
Title to be confirmed

Abstract not available

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Wed 08 May 14:00: Title to be confirmed

http://talks.cam.ac.uk/show/rss/15125 - Thu, 25/04/2024 - 14:17
Title to be confirmed

Abstract not available

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Wed 01 May 14:00: Title to be confirmed

http://talks.cam.ac.uk/show/rss/15125 - Thu, 25/04/2024 - 14:16
Title to be confirmed

Abstract not available

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Wed 24 Apr 17:30: Natural and forced behaviour of the Pacific Walker Circulation over the past 800 years Building doors are card operated, so latecomers may not be able to access the venue.

http://talks.cam.ac.uk/show/rss/17246 - Tue, 23/04/2024 - 14:33
Natural and forced behaviour of the Pacific Walker Circulation over the past 800 years

The Pacific Walker Circulation (PWC) is an important part of the global climate system, and affects weather and climate all over the world. However, our observational records of the climate system are too short to characterise the PWC ’s long-term internal variability, as well as how the PWC responds to external forcings such as volcanic eruptions and anthropogenic forcings.

In this seminar I will share a reconstruction of the PWC ’s behaviour over the past 800 years. I will outline how I calculated this reconstruction using a network of globally-distributed water isotope proxy records, as well as how I quantified uncertainties from different sources. I will share some new insights this reconstruction has allowed, including a close examination of the PWC ’s response to both volcanic and anthropogenic forcing.

Building doors are card operated, so latecomers may not be able to access the venue.

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Wed 24 Apr 17:30: Natural and forced behaviour of the Pacific Walker Circulation over the past 800 years Building doors are card operated, so latecomers may not be able to access the venue.

http://talks.cam.ac.uk/show/rss/15125 - Tue, 23/04/2024 - 14:33
Natural and forced behaviour of the Pacific Walker Circulation over the past 800 years

The Pacific Walker Circulation (PWC) is an important part of the global climate system, and affects weather and climate all over the world. However, our observational records of the climate system are too short to characterise the PWC ’s long-term internal variability, as well as how the PWC responds to external forcings such as volcanic eruptions and anthropogenic forcings.

In this seminar I will share a reconstruction of the PWC ’s behaviour over the past 800 years. I will outline how I calculated this reconstruction using a network of globally-distributed water isotope proxy records, as well as how I quantified uncertainties from different sources. I will share some new insights this reconstruction has allowed, including a close examination of the PWC ’s response to both volcanic and anthropogenic forcing.

Building doors are card operated, so latecomers may not be able to access the venue.

Add to your calendar or Include in your list