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A list of talks related to sustainability and the environment
URL: http://talks.cam.ac.uk/show/index/22840
Updated: 40 min 44 sec ago

Wed 12 Mar 14:00: Spatio-temporal Melt and Basal Channel Evolution on Pine Island Glacier Ice Shelf from CryoSat-2

Mon, 24/02/2025 - 09:59
Spatio-temporal Melt and Basal Channel Evolution on Pine Island Glacier Ice Shelf from CryoSat-2

Ice shelves buttress the grounded ice sheet, restraining its flow into the ocean. Mass loss from these ice shelves occurs primarily through ocean-induced basal melting, with the highest melt rates occurring in regions that host basal channels – elongated, kilometre-wide zones of relatively thin ice. While some models suggest that basal channels could mitigate overall ice shelf melt rates, channels have also been linked to basal and surface crevassing, leaving their cumulative impact on ice-shelf stability uncertain. Due to their relatively small spatial scale and the limitations of previous satellite datasets, our understanding of how channelised melting evolves over time remains limited. In this study, we present a novel approach that uses CryoSat-2 radar altimetry data to calculate ice shelf basal melt rates, demonstrated here as a case study over Pine Island Glacier (PIG) ice shelf. Our method generates monthly Digital Elevation Models (DEMs) and melt maps with a 250 m spatial resolution. The data show that near the grounding line, basal melting preferentially melts a channel’s western flank 50% more than its eastern flank. Additionally, we find that the main channelised geometries on PIG are inherited upstream of the grounding line and play a role in forming ice shelf pinning points. These observations highlight the importance of channels under ice shelves, emphasising the need to investigate them further and consider their impacts on observations and models that do not resolve them.

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Thu 06 Mar 11:30: Reactions in Porous Rocks

Mon, 24/02/2025 - 09:42
Reactions in Porous Rocks

Abstract not available

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Thu 27 Feb 11:30: Green Carbon for the Chemical Industry: Decoupling Polymers from Fossil Resources

Mon, 24/02/2025 - 09:30
Green Carbon for the Chemical Industry: Decoupling Polymers from Fossil Resources

Reducing reliance on fossil carbon is central to the concepts of sustainable development and material stewardship. Whereas decarbonization of the energy sector is feasible through the development of renewable energy, the chemicals sector needs carbon as a building block. The lasting and growing demand for this embedded carbon, especially for production of polymers, must be met in the future through utilization of renewable feedstocks such as biomass, CO2 and recycling of carbon-containing waste. In this context, the transition from fossil to renewable polymers provides a major challenge. Advances in renewable polymers will be exemplified through case studies of two of the most promising bio-based platforms for plastics: lactic acid (LA) and hydroxymethylfurfural (HMF).

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Tue 18 Feb 11:00: Searching for Life in Stranger Seas https://teams.microsoft.com/l/meetup-join/19%3ameeting_N2YxZjU5NTgtYzIwNi00MTY2LThkY2ItZjQyMTJmNjdkMWQw%40thread.v2/0?context=%7b%22Tid%22%3a%2249a50445-bdfa-4b79-ade3-547b4f3986e9%22%2c%22Oid%22%3a...

Mon, 17/02/2025 - 11:35
Searching for Life in Stranger Seas

With a planet teaming with life all around us, it is tempting to think that any life on other worlds must be like Earth life. But is that true, and if it is not, what limits can we place on where we might look for life on other worlds? Starting from the still-controversial possibility of the presence of phosphine in the clouds of Venus, I will discuss what we know (not much) can model (some) and speculate about how the chemistry of life might work on other worlds under conditions very different from Earth. In particular, different atmospheres give different chemistries, possibly chemistries that use solvents other than water as their base. Alternative solvents open up the possibility of life on many bodies previously considered uninhabitable, such as the clouds of Venus, the surface of Mars, even the Moon. I will end with some thoughts on complex, even intelligent, life and where we might find it.

https://teams.microsoft.com/l/meetup-join/19%3ameeting_N2YxZjU5NTgtYzIwNi00MTY2LThkY2ItZjQyMTJmNjdkMWQw%40thread.v2/0?context=%7b%22Tid%22%3a%2249a50445-bdfa-4b79-ade3-547b4f3986e9%22%2c%22Oid%22%3a%2253b919d9-f8a7-4f56-9bb0-baaf0ba7404d%22%7d

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Thu 20 Feb 11:30: Bubble growth in alkaline electrolysis

Mon, 17/02/2025 - 10:03
Bubble growth in alkaline electrolysis

In the production of hydrogen via electrolysis, bubbles of hydrogen and oxygen must grow and detach from the electrode. Discussion of factors effecting rate of bubble growth and final detachment volume, and their contribution to overall efficiency.

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Thu 27 Feb 16:00: Antarctic Atmospheric Rivers in the Present and Future Climates

Mon, 17/02/2025 - 07:42
Antarctic Atmospheric Rivers in the Present and Future Climates

Despite occurring only ~1% of the time, Antarctic atmospheric rivers (ARs) contribute 10% of the annual precipitation and are major drivers for heatwaves, foehn events, and surface melting on ice shelves. While snowfall is currently the dominant impact of ARs on Antarctica, the relative contribution of ARs to snowfall, rainfall, and surface melt may change in a warming climate, along with the frequency and intensity of AR events themselves. Here, we use a suite of global climate models, including the Community Earth System Model version 2 (CESM2) Large Ensemble and the US Department of Energy’s Exascale Earth System Model version 2 (E3SMv2), to detect ARs during the current period (1980–2014) and future climate (2015–2100) under the SSP370 radiative forcing scenario. We use an AR detection threshold for the current period based on the 98th percentile of the meridional component of integrated vapor transport (vIVT). To account for projected future increases in atmospheric moisture content (Clausius-Clapeyron effect) and its impacts on vIVT, we scale our AR detection threshold for the future period by the relative change in integrated water vapor compared to the present-day climatology. We then describe how the frequency and variability of Antarctic ARs changes by the end of the 21st century by region, with links to changes in the large-scale atmospheric circulation accompanying ARs. Finally, we quantify AR-attributed precipitation, precipitation variability, and trends in the future climate, ultimately providing an early assessment of future AR-driven changes to Antarctic surface mass balance.

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Wed 26 Feb 15:30: The Impacts of Freshwater Transport on the Weddell Gyre Carbon Budget

Fri, 14/02/2025 - 17:36
The Impacts of Freshwater Transport on the Weddell Gyre Carbon Budget

The Weddell Gyre mediates carbon exchange between the abyssal ocean and atmosphere, which is critical to global climate. This region also features large and highly variable freshwater fluxes due to seasonal sea ice, net precipitation, and glacial melt; however, the impact of these freshwater fluxes on the regional carbon cycle has not been fully explored. Using a novel budget analysis of dissolved inorganic carbon (DIC) mass in the Biogeochemical Southern Ocean State Estimate and revisiting hydrographic analysis from the ANDREX cruises, we highlight two freshwater-driven transports. Where freshwater with minimal DIC enters the ocean, it displaces DIC -rich seawater outwards, driving a lateral transport of 75±5 Tg DIC /year. Additionally, sea ice export requires a compensating import of seawater, which carries 48±11 Tg DIC /year into the gyre. Though often overlooked, these freshwater displacement effects are of leading order in the Weddell Gyre carbon budget in the state estimate and in regrouped box-inversion estimates. Implications for evaluating basin-scale carbon transports are considered. [Time permitting, I’ll also share some results on the role of heat addition in driving circulation change and warming patterns in the Indian sector of the Southern Ocean.]

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Thu 20 Feb 16:30: Innovations in Nuclear Energy

Fri, 14/02/2025 - 16:11
Innovations in Nuclear Energy

Join the Nuclear Energy Master programme as we explore recent innovations and developments in advance nuclear reactor design, presented by NEWCLEO ’s Daniel Finnigan and the application of nuclear energy in maritime propulsion by COREPOWER ’s Ioannis Kourasis and Oscar Hamilton.

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Wed 26 Feb 15:30: Freshwater displacement effect on the Weddell Gyre carbon budget

Fri, 14/02/2025 - 11:13
Freshwater displacement effect on the Weddell Gyre carbon budget

The Weddell Gyre mediates carbon exchange between the abyssal ocean and atmosphere, which is critical to global climate. This region also features large and highly variable freshwater fluxes due to seasonal sea ice, net precipitation, and glacial melt; however, the impact of these freshwater fluxes on the regional carbon cycle has not been fully explored. Using a novel budget analysis of dissolved inorganic carbon (DIC) mass in the Biogeochemical Southern Ocean State Estimate and revisiting hydrographic analysis from the ANDREX cruises, we highlight two freshwater-driven transports. Where freshwater with minimal DIC enters the ocean, it displaces DIC -rich seawater outwards, driving a lateral transport of 75±5 Tg DIC /year. Additionally, sea ice export requires a compensating import of seawater, which carries 48±11 Tg DIC /year into the gyre. Though often overlooked, these freshwater displacement effects are of leading order in the Weddell Gyre carbon budget in the state estimate and in regrouped box-inversion estimates. Implications for evaluating basin-scale carbon transports are considered. [Time permitting, I’ll also share some results on the role of heat addition in driving circulation change and warming patterns in the Indian sector of the Southern Ocean.]

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Wed 21 May 14:30: Title to be confirmed

Thu, 13/02/2025 - 11:50
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Abstract not available

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Wed 23 Apr 14:00: Title to be confirmed

Thu, 13/02/2025 - 11:48
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Abstract not available

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Wed 09 Apr 15:00: Title to be confirmed

Thu, 13/02/2025 - 11:48
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Abstract not available

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Wed 19 Mar 14:00: Tipping points of the Ross and Filchner-Ronne Ice Shelves: how worried should we be?

Thu, 13/02/2025 - 11:47
Tipping points of the Ross and Filchner-Ronne Ice Shelves: how worried should we be?

Ocean models consistently project that with sufficient climate change forcing, the Ross and Filchner-Ronne ice shelf cavities could abruptly transition from a cold state to a warm state. Crossing these tipping points would have profound consequences for basal melt rates, buttressing of ice streams, and ultimately sea level rise. Here we analyse over 14,000 years of “overshoot” simulations with the UK Earth System Model, which includes a fully coupled Antarctic Ice Sheet. As the climate warms, stabilises at different temperatures, and cools again, we simulate many examples of the cavities tipping and recovering. We find that global warming thresholds of around 3.5°C and 5°C tip the Ross and Filchner-Ronne respectively. We also find evidence of hysteresis: the climate must cool back down beyond the tipping thresholds in order for each cavity to return to its original cold state. Even if the oceanography recovers, the ice sheet does not: sea level contribution from each catchment takes centuries even to stabilise, and the ice does not begin to regrow on this timescale. Therefore, if the Ross or Filchner-Ronne Ice Shelves cross tipping points, the resulting sea level rise will be effectively irreversible.

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Wed 26 Mar 15:30: Title to be confirmed

Thu, 13/02/2025 - 11:46
Title to be confirmed

Abstract not available

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Wed 12 Mar 14:00: Title to be confirmed

Thu, 13/02/2025 - 11:46
Title to be confirmed

Abstract not available

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Wed 26 Feb 15:30: Title to be confirmed

Thu, 13/02/2025 - 11:43
Title to be confirmed

Abstract not available

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Mon 17 Mar 13:00: Volcanic fissure localisation and lava delta formation: Modelling of volcanic flows undergoing rheological evolution

Tue, 11/02/2025 - 17:18
Volcanic fissure localisation and lava delta formation: Modelling of volcanic flows undergoing rheological evolution

In this talk, I will present two volcanologically motivated modelling problems. In the first, I will detail how thermoviscous localisation of volcanic eruptions is influenced by the irregular geometry of natural volcanic fissures. Fissure eruptions typically start with the opening of a linear fissure that erupts along its entire length, following which activity localises to one or more isolated vents within a few hours or days. Previous work has proposed that localisation can arise through a thermoviscous fingering instability driven by the strongly temperature dependent viscosity of the rising magma. I will show that, even for relatively modest variations of the fissure width, a non-planar geometry supports strongly localised steady states, in which the wider parts of the fissure host faster, hotter flow, and the narrower parts of the fissure host slower, cooler flow. This geometrically-driven localisation differs from the spontaneous thermoviscous fingering localisation observed in planar geometries, and is potentially more potent for parameter values relevant to volcanic fissures.

The second problem concerns lava delta formation. A lava delta arises when a volcanic lava flow enters a body of water, extending the pre-eruption shoreline via the creation of new, relatively flat land. A combination of cooling induced rheological changes and the reduction in gravitational driving forces controls the morphology and evolution of the delta. I will present shallow-layer continuum models for this process, highlighting how different modes of delta formation manifest in different late-time behaviours. In particular, I will derive a steady state shoreline extent when the delta formation is driven only by buoyancy forces, and late time similarity solutions for the evolution of the shoreline when the viscous lava fragments and forms `hyaloclastic’ debris on contact with the water.

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Mon 03 Mar 13:00: Intensified shelf break exchange through submarine canyons: upwelling, internal tides, and turbidity currents

Mon, 10/02/2025 - 16:46
Intensified shelf break exchange through submarine canyons: upwelling, internal tides, and turbidity currents

Submarine canyons are a ubiquitous feature of continental margins worldwide and their complex geomorphology controls several physical processes that intensify the exchange of water masses, nutrients and carbon across the shelf break – from shallow shelf seas to the deep open ocean, and vice versa. In this seminar, I will illustrate three important shelf break exchange processes that are strongly controlled by submarine canyon geomorphology and discuss their interdisciplinary impacts. I will then highlight some previous and current research into these processes, applied to an exemplar submarine canyon close to the UK, and introduce two exciting upcoming projects that will further elucidate our understanding.

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Wed 12 Feb 13:00: Short-term, high-resolution sea ice forecasting with diffusion model ensembles

Mon, 10/02/2025 - 15:27
Short-term, high-resolution sea ice forecasting with diffusion model ensembles

Sea ice plays a key role in Earth’s climate system and exhibits significant seasonal variability as it advances and retreats across the Arctic and Antarctic every year. The production of sea ice forecasts provides great scientific and practical value to stakeholders across the polar regions, informing shipping, conservation, logistics, and the daily lives of inhabitants of local communities. Machine learning offers a promising means by which to develop such forecasts, capturing the nonlinear dynamics and subtle spatiotemporal patterns at play as effectively—if not more effectively—than conventional physics-based models. In particular, the ability of deep generative models to produce probabilistic forecasts which acknowledge the inherent stochasticity of sea ice processes and represent uncertainty by design make them a sensible choice for the task of sea ice forecasting. Diffusion models, a class of deep generative models, present a strong option given their state-of-the-art performance on computer vision tasks and their strong track record when adapted to spatiotemporal modelling tasks in weather and climate domains. In this talk, I will present preliminary results from a IceNet-like [1] diffusion model trained to autoregressively forecast daily, 6.25 km resolution sea ice concentration in the Bellingshausen Sea along the Antarctic Peninsula. I will also touch on the downstream applications for these forecasts, from conservation to marine route planning, which are under development at the British Antarctic Survey (BAS). I welcome ideas and suggestions for improvement and look forward to discussing opportunities for collaboration within and beyond BAS .

[1] Andersson, Tom R., et al. “Seasonal Arctic sea ice forecasting with probabilistic deep learning.” Nature communications 12.1 (2021): 5124. https://www.nature.com/articles/s41467-021-25257-4

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Fri 21 Feb 17:30: Eve's Byte of the Apple

Sun, 09/02/2025 - 12:42
Eve's Byte of the Apple

Abstract:

In “Eve’s Byte of the Apple”, Sandi Toksvig will be taking an alternative look at the evolution of information, at how the knowledge of women and about women is encoded, and what comes from those codes. Since 2023 Sandi has been a Bye-Fellow at Christ’s College, Cambridge working on The Mappa Mundi Project, creating a global interactive digital platform telling women’s stories worldwide. In this lecture, she considers how the evolution of information technology has been historically biased against women, continuing that bias to the present day. Most importantly, she asks what might be done about it.

Biography:

Sandi Toksvig was born in Copenhagen, Denmark but grew up travelling the world. After graduating with a first-class degree from Cambridge, Sandi began a career on stage, television and radio. As a political and women’s rights activist, she was co-founder of the Women’s Equality Party in 2015. Sandi has written stage plays, journalism and over 25 books including fact and fiction for both children and adults. Her latest novel Friends of Dorothy was published in 2024.

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