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Department of Earth Sciences

 
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A collection of all the seminars going on at the Department, either on the downtown site, or out at the Bullard Laboratories
Updated: 4 min 21 sec ago

Wed 05 May 16:00: Title to be confirmed

Wed, 14/04/2021 - 21:47
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Wed 28 Apr 16:00: Core formation on Earth and Mars

Wed, 14/04/2021 - 20:46
Core formation on Earth and Mars

The terrestrial planets accreted in a series of increasingly large and violent impacts, which caused large-scale melting of the mantle. This allowed the core to segregate during accretion, undergoing high pressure, high temperature metal–silicate partitioning reactions that set the modern-day compositions of the core and mantle. This talk will present a model of Earth’s core formation, which builds upon a suite of N-body accretion simulations and experimental partitioning data, with applications to the composition of Earth’s core and the core formation process. Modeling of the Hf–W isotopic system will then be discussed, which can place tighter constraints on the core formation process in the Earth. Finally, a model of Martian core formation will be presented, which can be used to compare and contrast this process on the two planets.

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Wed 05 May 16:00: Title to be confirmed

Tue, 13/04/2021 - 11:40
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Wed 16 Jun 16:00: Title to be confirmed

Mon, 12/04/2021 - 14:08
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Wed 02 Jun 16:00: Title to be confirmed

Mon, 12/04/2021 - 14:04
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Wed 26 May 16:00: Title to be confirmed

Mon, 12/04/2021 - 14:04
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Wed 19 May 16:00: Title to be confirmed

Mon, 12/04/2021 - 14:03
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Wed 12 May 16:00: Title to be confirmed

Mon, 12/04/2021 - 14:02
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Wed 28 Apr 16:00: Title to be confirmed

Mon, 12/04/2021 - 14:00
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Thu 22 Apr 15:00: Reconstructing a deep time Earth system: The penultimate ice house

Wed, 24/03/2021 - 10:55
Reconstructing a deep time Earth system: The penultimate ice house

Earth system science, the study of our planet as an integrated set of subsystems that drive planetary function is applicable to the geologic past, i.e., the deep time, made possible by the advent of high precision radioisotope dating, the potential for astronomically calibrating stratigraphic intervals, and the application of Earth System (climate) Models and process-based ecosystem models to deep time studies. In this talk we discuss three components of our collective effort to develop a ‘whole-Earth’ reconstruction of the penultimate icehouse—the Late Paleozoic Ice Age (LPIA), 300 Ma. For the first component, we present a multi-proxy record of atmospheric CO2 over 40 million years of this icehouse and its turnover to a permanent greenhouse revealing CO2 variability (160 and 750 ppm) in-step with the glaciation history and with repeated restructuring of Pangaean tropical biomes on the eccentricty to million-year scales. In the second component, we couple the atmospheric composition records with plant fossil measurements and process-based ecosystem modelling to reconstruct the paleo-physiology/functioning of the extinct plants and to suggest possible ecosystem-scale vegetation-climate-CO2 feedbacks that would have influenced water cycling, surface runoff and weatherability, and organic carbon burial. In the third component, we use an isotope-enabled Earth system model to simulate the influence of glacial-interglacial fluctuations in atmospheric CO2 on epicontinental to global-scale ocean circulation and oxygen isotopic composition. This ‘systems’ perspective of the Earth’s penultimate icehouse reveals unique insights into the response of land-atmosphere-ocean interactions to a range of atmospheric CO2 within that projected for our future.

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Thu 08 Apr 15:00: The small and mighty: the role of microbes and minerals in melting the Greenland Ice Sheet

Wed, 24/03/2021 - 10:54
The small and mighty: the role of microbes and minerals in melting the Greenland Ice Sheet

The rapid melting of the Greenland Ice Sheet and the associated sea level rise is controlled by changes in albedo, which is primarily a consequence of increased light absorbing particulates (LAP) on snow and ice surfaces. Among LAPs, and included in climate models is black carbon. However, other LAPs so far not included in climate models because their role is poorly quantified, are mineral dust and pigmented glacier algae. We will show pigmented algae can reduce albedo by up to ~ 20 %, and that a necessary interplay between geochemical, mineralogical and microbiological parameters helps trigger the annual mineral-nutrient fuelled glacial algal blooms. We ground truth and link surface, airborne and satellite data and determine the role and consequences of water-mineral-microbe interface reactions in shaping large-scale processes across the Greenland Ice Sheet.

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Thu 25 Mar 15:00: Global climate change mitigation under the COVID-19 new normal

Wed, 24/03/2021 - 10:53
Global climate change mitigation under the COVID-19 new normal

The global economy is facing a serious recession due to COVID -19, with implications for CO2 emissions. Here, using a global adaptive multiregional input–output model and scenarios of lockdown and fiscal counter measures, we show that global emissions from economic sectors will decrease by 3.9 to 5.6% in 5 years (2020 to 2024) compared with a no-pandemic baseline scenario (business as usual for economic growth and carbon intensity decline). Global economic interdependency via supply chains means that blocking one country’s economic activities causes the emissions of other countries to decrease even without lockdown policies. We stimulate possible post-covid recovery pathways (grey vs. green) under different fiscal stimuli packages for developed, emerging economies and low income countries, respectively.

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Fri 26 Mar 10:35: Volcanic crystals as archives of pre-eruptive processes

Wed, 17/03/2021 - 14:11
Volcanic crystals as archives of pre-eruptive processes

Volcanic crystals provide detailed records of the inner workings of volcanoes and improve our understanding of the depths, processes and timescales of magma transport, storage and eruption. The growth stratigraphy of minerals sampled by erupted magmas provides a unique archive of processes leading to eruption, including mixing, replenishment, differentiation and mobilisation of mantle-to-crustal reservoirs. The identification of eruption triggers from the mineral record has implications for the understanding of trans-crustal magma feeder systems, the monitoring of active volcanoes and their associated hazards. This talk will interrogate magmatic systems from a crystal perspective, highlighting recent technical advances and future directions.

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Thu 18 Mar 15:00: How are water isotopes influencing our understanding of Antarctic climate variability over the past 2000 years?

Tue, 16/03/2021 - 14:09
How are water isotopes influencing our understanding of Antarctic climate variability over the past 2000 years?

Under the current global warming trend, the Arctic is warming the fastest, and strangely, many parts of Antarctica are not warming at all. The delayed response of the high latitudes of Southern Hemisphere to the Greenhouse warming is an important observation that is not reproduced by the current generation of global climate models. One of the leading hypotheses to explain this discrepancy is that natural variability is particularly large in the southern high latitudes, masking the anthropogenic forcing, and that this large variability is not well reproduced by models. Quantifying internal variability and understanding its cause is important for our understanding of the potential response of Antarctica to climate change, and to improve projections. Here, we will review our knowledge of Antarctic climate variability from ice cores covering the past 2000 years. This is an interval sufficiently short to have observations from many places in Antarctica, and sufficiently long to investigate variability at decadal and longer timescales. Temperature reconstructions come mainly from water isotopes, but they are not a perfect temperature recorder. The central thread of this talk will be to discuss how our vision of climate variability is distorted by the water-isotopes lens. We will discuss the importance of precipitation bias on the deposited ice water isotope signal, using isotope enabled climate models over the reanalysis period (1979-present), and illustrate the impact of this sampling bias by contrasting the expression of circulation modes (such as the SAM ) on temperature and d18O. In the second part of the talk, we will review evidence from other temperature proxies, especially borehole temperature records and temperature reconstructions from inert gas isotopes (d15N-excess), and discuss how the different records can be reconciled into a coherent view of Antarctic climate evolution over the past 2ka. If time allows, we will briefly discuss model-data comparisons over the last millennium, and review hypothesis about why models (OA-GCM) under-estimate internal variability in the high latitude Southern Hemisphere.

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