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A list of talks related to sustainability and the environment
URL: http://talks.cam.ac.uk/show/index/22840
Updated: 13 min 27 sec ago

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

Thu, 30/01/2025 - 09:59
Antarctic Atmospheric Rivers in the Present and Future Climates

Abstract not available

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Thu 06 Mar 17:00: West Antarctic Ice Sheet readvance in the Holocene

Thu, 30/01/2025 - 09:58
West Antarctic Ice Sheet readvance in the Holocene

Sea-level rise is accelerating, predominantly due to the ice sheets shrinking. There is significant uncertainty as to how this will continue. Understanding how ice sheets have changed in the past can improve our predictions of future change by highlighting important processes and helping to test and tune ice-sheet models. This talk is about how West Antarctica changed during the Holocene. Until recently, it was assumed that the West Antarctic Ice Sheet shrank monotonically from an expanded state at the Last Glacial Maximum (LGM), to its current state, which it then maintained through most of the Holocene. In this talk I will describe a decade of work by myself and many others suggesting that after the LGM the ice sheet instead shrank to a size significantly smaller than today, then regrew to its current size in the Weddell and Ross sea sectors. In places, the grounding line may have reached more than 200 km inland of its current position.

The cause of the retreat and readvance is debated. Potential causes include glacial isostatic adjustment (GIA) and climate fluctuations. Which proves the best explanation has implications for our understanding of these sectors’ sensitivity to future climate-driven changes.

I will discuss a wide range of evidence for retreat and readvance. This includes englacial structure mapped with ice-penetrating radar, englacial temperatures measured in boreholes, radiocarbon in subglacial water and sediments, and indicators of relative sea-level change. I will also discuss what these observations tell us about the timing of retreat and readvance and several modelling studies aimed at determining the cause of these changes. Finally, I will discuss future work that could improve our understanding of these sectors of the ice sheet and their climate sensitivity.

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Thu 20 Mar 16:00: Just Ice For All: Global Ice-Thickness Inversions and Committed Ice Loss to 2050

Thu, 30/01/2025 - 09:58
Just Ice For All: Global Ice-Thickness Inversions and Committed Ice Loss to 2050

Abstract not available

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Wed 29 Jan 14:00: Modelling sea ice dynamics using brittle dynamics: impact in pack ice and marginal ice zones

Wed, 29/01/2025 - 11:02
Modelling sea ice dynamics using brittle dynamics: impact in pack ice and marginal ice zones

Sea ice dynamics are highly complex and generally poorly resolved by sea ice models. This is problematic, as they modulate the amount of momentum exchanged between the atmosphere and the ocean in polar regions, as well as play a key role in heat and light fluxes through the opening/closing of sea ice leads. A solution to improve simulated sea ice dynamics is to use a brittle rheology to represent the mechanical behaviour of sea ice. Such rheology is included in the sea ice model neXtSIM, and we demonstrated its ability to capture the observed characteristics and complexity of fine-scale sea ice deformations.Here, we present two cases where we coupled this sea ice model to better understand the role of ice dynamics in ice-ocean interactions.

In the first case, we set up a 12km resolution ocean—sea-ice coupled model, using OPA , the ocean component of NEMO . We investigate the sea ice mass balance of the model for the period 2000-2018. We estimate the contribution of leads and polynyas to winter ice production. We find this contribution to add up from 25% to 35% of the total ice growth in pack ice in winter, showing a significant increase over the 18 years covered by the model simulation.

In the second case, we focus on the marginal ice zone (MIZ) and couple neXtSIM with the wave model WAVEWATCH III . We investigate how wave-induced breakup impacts sea ice dynamics in the MIZ . We show how, using the “damage” quantity that is at the core of the brittle rheology framework, we can represent the loss of ice strength associated with wave-induced breakup, and how breakup can increase the mobility of the thickest ice in the MIZ after storms. For both cases, we will also discuss briefly how using a brittle sea ice model could impact the modelling of Antarctic sea ice using preliminary results from a new configuration.

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Wed 12 Feb 14:00: Short-term, high-resolution sea ice forecasting with diffusion model ensembles

Tue, 28/01/2025 - 09:21
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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Tue 04 Mar 11:00: High-Resolution PM2.5 Mapping Across Malaysia Using Multi-Satellite Data and Machine Learning Techniques https://teams.microsoft.com/l/meetup-join/19%3ameeting_MTQ5N2Q5ZDYtODRmYi00MzJhLTg0ZjctNjc2NGVlZDUzYmUx%40thread.v2/0?context=%7b...

Mon, 27/01/2025 - 22:44
High-Resolution PM2.5 Mapping Across Malaysia Using Multi-Satellite Data and Machine Learning Techniques

Air pollution assessment in urban and rural areas is really challenging due to high spatio-temporal variability of aerosols and pollutants and the uncertainties in measurements and modelling estimates. Nevertheless, accurate determination of the pollution sources and distribution of PM2 .5 concentrations is especially important for source apportionment and mitigation strategies. This study provides estimates of PM2 .5 concentrations across Malaysia in high spatial resolution, based on multi-satellite data and machine learning (ML) models, namely Random Forest (RF), Support Vector Regression (SVR) and extreme Gradient Boosting (XGBoost), also covering remote areas without measurement networks. The study aims to develop ML models that are simpler than previous works and demonstrate computational efficiency. Six sub-models were developed to represent different locations and seasons in Malaysia. Model 1 includes all data from 65 air-quality stations, Models 2 and 3 characterize urban/industrial and suburban sites, respectively, while Models 4 to 6 correspond to dry, wet, and inter-monsoon seasons, respectively. The RF technique exhibited slightly better performance compared to the XGBoost and SVR approaches. More specifically, for model 1, it exhibited a high correlation with a coefficient of determination (R2) of 0.64 and RMSE of 12.17 μg m−3, while similar results were obtained for models 3, model 4 and model 5. The lower performance (R2 = 0.16-0.94) observed in the wet and inter-monsoon seasons is due to fewer numbers of data used in model calibration. Integration of two Aerosol Optical Depth products from the Advanced Himawari Imager and Visible Infrared Imaging Radiometer Suite (VIIRS) sensors together with gases pollutants from Sentinel 5P enabled seamless seasonal PM2 .5 mapping over Malaysia, even for a short period of time. However, usage of data with insufficient information during the model training procedure, and lack of satellite data due to cloud contamination, can limit the PM2 .5 prediction accuracy.

https://teams.microsoft.com/l/meetup-join/19%3ameeting_MTQ5N2Q5ZDYtODRmYi00MzJhLTg0ZjctNjc2NGVlZDUzYmUx%40thread.v2/0?context=%7b%22Tid%22%3a%2249a50445-bdfa-4b79-ade3-547b4f3986e9%22%2c%22Oid%22%3a%228b208bd5-8570-491b-abae-83a85a1ca025%22%7d

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Tue 04 Feb 11:00: Could stratospheric aerosol injection produce meaningful global cooling without novel aircraft? https://teams.microsoft.com/l/meetup-join/19%3ameeting_ZjVmYTU2YmItNmMyZC00NGYzLTllZmMtNGU5OWJiMjlhNDAy%40thread.v2/0?context=%7b%22Tid%22...

Mon, 27/01/2025 - 22:33
Could stratospheric aerosol injection produce meaningful global cooling without novel aircraft?

Stratospheric aerosol injection (SAI) is a proposed method of cooling the planet and reducing the impacts of climate change by adding a layer of small particles to the high atmosphere where they would reflect a fraction of incoming sunlight. While it is likely that SAI could reduce global temperature, it has many serious risks and would not perfectly offset climate change. For SAI to be effective, injection would need to take place in the stratosphere. The height of the transition to the stratosphere decreases with latitude, from around 17km near the equator to 8km near the poles. The required injection height would therefore also decrease for higher latitude injection. In this talk, I will present simulations of SAI in an earth system model, UKESM , which quantify how impacts would vary with the injection location and timing, focusing on low-altitude high-latitude injection strategies. Our results suggest that SAI could meaningfully cool the planet even if limited to using existing large jets and injecting at around 13km altitude, if this injection is in the high latitudes during spring and summer. However, relative to a more optimal deployment with novel aircraft at 20km, this strategy requires three times more sulphur dioxide injection and so would strongly increase some side-effects.

https://teams.microsoft.com/l/meetup-join/19%3ameeting_ZjVmYTU2YmItNmMyZC00NGYzLTllZmMtNGU5OWJiMjlhNDAy%40thread.v2/0?context=%7b%22Tid%22%3a%2249a50445-bdfa-4b79-ade3-547b4f3986e9%22%2c%22Oid%22%3a%228b208bd5-8570-491b-abae-83a85a1ca025%22%7d

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Mon 10 Mar 13:00: Ice Shelves: Antarctica’s Gatekeepers

Mon, 27/01/2025 - 15:13
Ice Shelves: Antarctica’s Gatekeepers

Abstract not available

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Mon 24 Feb 13:00: Human Judgement and Decision-Making Under Uncertainty

Fri, 24/01/2025 - 16:50
Human Judgement and Decision-Making Under Uncertainty

A weather forecast is only useful if appropriate decisions are made on the basis of the forecast. This presents a challenge, because weather forecasts are innately uncertain. How do we ensure that the likelihood of an event, particularly for extreme and impactful weather, is understood and acted upon? This is where psychology meets physics, and where the application of mathematical understanding is key.

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Wed 19 Mar 17:30: Rise and fall of Bronze Age Mediterranean societies: a new geoarchaeological and chronostratigraphic sequence of Nuragic Sardinia

Fri, 24/01/2025 - 04:34
Rise and fall of Bronze Age Mediterranean societies: a new geoarchaeological and chronostratigraphic sequence of Nuragic Sardinia

Around the beginning of the Late Holocene (4,200 years BP) across the western Mediterranean regions, Bronze Age societies developed unique socio-economic and political complexity reflected in the construction of monumental stone architecture. New geoarchaeological and chronostratigraphic research in Sardinia, Italy, exposes for the first time the environmental underpinnings of the expansion and decline of the Nuragic Bronze Age monument-building society. These findings also highlight the role of prehistoric societies in shaping the landscape of the Mediterranean region over the Holocene. Multi-proxy geoarchaeological analyses—including soil micromorphology, XRD mineralogy, magnetic susceptibility, and geochemistry—reveal that the Bronze Age climax soil type of basaltic mesas in Sardinia was a dark Vertisol rich in primary nutrients and montmorillonite clay. These fertile soils sustained grassland ecosystems and played a key role in the distribution of early Middle Bronze Age Nuragic monuments across Sardinia’s basaltic landscapes. However, prolonged and intensified land use, particularly animal herding and agriculture, to support monument construction led to soil erosion and, ultimately, the replacement of deep, nutrient-rich Vertisol cover with a thin, oxidised and vertic Cambisol one. These processes resulted in a significant increase in sediment supply in the catchment east of the mesa, causing a new major phase of alluviation in the valley bottoms during the Late Holocene. These landscape changes triggered a socio-environmental crisis marked by the abandonment of the mesa at the end of the Middle Bronze Age, hence excluding the influence of a climate change in causing the local societal collapse.

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Wed 19 Mar 17:30: Rise and fall of Bronze Age Mediterranean societies: a new geoarchaeological and chronostratigraphic sequence of Nuragic Sardinia

Fri, 24/01/2025 - 04:34
Rise and fall of Bronze Age Mediterranean societies: a new geoarchaeological and chronostratigraphic sequence of Nuragic Sardinia

Around the beginning of the Late Holocene (4,200 years BP) across the western Mediterranean regions, Bronze Age societies developed unique socio-economic and political complexity reflected in the construction of monumental stone architecture. New geoarchaeological and chronostratigraphic research in Sardinia, Italy, exposes for the first time the environmental underpinnings of the expansion and decline of the Nuragic Bronze Age monument-building society. These findings also highlight the role of prehistoric societies in shaping the landscape of the Mediterranean region over the Holocene. Multi-proxy geoarchaeological analyses—including soil micromorphology, XRD mineralogy, magnetic susceptibility, and geochemistry—reveal that the Bronze Age climax soil type of basaltic mesas in Sardinia was a dark Vertisol rich in primary nutrients and montmorillonite clay. These fertile soils sustained grassland ecosystems and played a key role in the distribution of early Middle Bronze Age Nuragic monuments across Sardinia’s basaltic landscapes. However, prolonged and intensified land use, particularly animal herding and agriculture, to support monument construction led to soil erosion and, ultimately, the replacement of deep, nutrient-rich Vertisol cover with a thin, oxidised and vertic Cambisol one. These processes resulted in a significant increase in sediment supply in the catchment east of the mesa, causing a new major phase of alluviation in the valley bottoms during the Late Holocene. These landscape changes triggered a socio-environmental crisis marked by the abandonment of the mesa at the end of the Middle Bronze Age, hence excluding the influence of a climate change in causing the local societal collapse.

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Fri 24 Jan 17:30: Bits with Soul

Thu, 23/01/2025 - 14:53
Bits with Soul

When people think of codes, coding, and computers, they often think of socially challenged nerds like me, writing “code” (whatever that might be) in a darkened basement, all soulless ones and zeros and glowing screens. But in fact computer science (the study of information, computation, and communication) gives us an enormously rich new lens through which to look at and explore the world. By encoding everything in the same, digital bits, we can mechanise the analysis and transformation of that information; we can explore it in ways that are simply inaccessible to manual techniques; we can engage our creativity to write programs whose complexity rivals the most sophisticated artefacts that human beings have produced—and yet fit on a USB drive; we can even learn from data in ways that have made “ChatGPT” into a verb practically overnight.

Given how closely digital technology is interwoven in our lives, having a visceral sense of how this stuff works, what it can do well, and how it can fail, is essential for us to survive and thrive, and should be part of every child’s education.

In my talk I will share some of the joy, beauty, and creativity of computer science. This is serious, because it impinges on our daily lives. But it is also rich, beautiful, and fun.

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Mon 03 Feb 13:00: The atmospheric response to Arctic amplification: Insights from idealised models

Wed, 22/01/2025 - 10:59
The atmospheric response to Arctic amplification: Insights from idealised models

Over recent decades the Arctic has warmed about three times as much as the global average, a phenomenon known as Arctic amplification (AA). There has been much interest in the extent to which AA can influence mid-latitude climate, with some studies suggesting that it may drive more frequent or long-lived weather extremes. However, general circulation models (GCMs) simulate widely diverging responses to polar heating, both in the mean atmospheric circulation and its variability. In this talk I will present two examples of recent work from my group, in which an idealised model, Isca, helps to explain some of the causes of this uncertainty. In the first, I will discuss the response of the persistence of surface temperature anomalies to AA. I will show that this response is large but absent in most GCM experiments due to the method by which they remove sea-ice. The persistence response is largest in the Arctic, but extends to mid-latitudes, where it is dynamically-driven, caused by a slowing of meridional wind anomalies. In the second example, I will discuss the ‘stratospheric pathway’, by which AA may dynamically impact lower latitudes. I will show that, by varying a single parameter that controls the mean strength of the stratospheric polar vortex, a range of stratospheric responses (both a strengthening and a weakening of the polar vortex) can be obtained, similar to the range seen in GCMs. These range of stratospheric responses, in turn, significantly impact the magnitude of the shift of the eddy-driven jet.

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Wed 12 Feb 17:30: The impact of climate-ice sheet interactions on abrupt climate changes in the long-term past and their importance for the future climate

Tue, 21/01/2025 - 14:56
The impact of climate-ice sheet interactions on abrupt climate changes in the long-term past and their importance for the future climate

The simulation of the last deglaciation (about 20.000 years before present to present) represents a hitherto unsolved challenge for comprehensive state-of-the-art climate models. During my presentation, I will introduce our novel coupled atmosphere-ocean-vegetation-ice sheet-solid earth model that is used to simulate the transient climate. An ensemble of transient model simulations successfully captures the main features of the last deglaciation, as depicted by proxy estimates. In addition, our model simulates a series of abrupt climate changes, which can be attributed to different drivers that will be discussed throughout the presentation. I will furthermore show, how the model can be applied for simulations of the long-term future. The future simulations show, that parts of the Antarctic ice sheet become unstable even under low-emission scenarios, with significant implications for the modelled climate response. Sensitivity experiments additionally show that, the Greenland ice sheet may exhibit multiple steady-states under pre-industrial climate conditions. This has significant implications for a potential regrowth, once disintegrated entirely.

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Wed 19 Feb 17:30: Reconstructing levels of volcanism in the late Pleistocene

Tue, 21/01/2025 - 14:55
Reconstructing levels of volcanism in the late Pleistocene

Volcanism is known to act as a driver of change to the Earth system on a range of scales. Degassing of greenhouse gases may act to drive global warming, whilst the weathering of fresh volcanic material may enhance the silicate weathering feedback and aid cooling of Earth’s climate. At the same time, the intensity of volcanism responds to other aspects of the Earth system. For example, low sea levels and low ice volumes may both act to increase levels of volcanic activity through the release of pressure on magma chambers. These interactions in turn may control the level of impact volcanism has as a driver of change. To fully understand the interaction between volcanic activity and climate, however, reliable records of changing volcanic intensity through time are required. Such records have been, to date, either regional or of low resolution. Here, I will discuss two approaches to this problem, firstly through the compilation of volcanic material occurrence in deep sea sediment cores. Secondly, I will present the application of inversion of atmospheric carbon dioxide records as an approach to reconstructing periods of imbalance and likely volcanic activity in the carbon cycle. Both approaches highlight a shift in the late Pleistocene at around 400 ka, whereby more volcanic activity is reconstructed, and the activity becomes cyclical in nature. This may be linked to Mid Brunhes Transition, a period of strengthening in amplitude of glacial-interglacial cycles, and indicates how Earth system changes may impact volcanic intensity.

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Mon 10 Feb 13:00: The structure and lifecycle of stratified mixing in forced shear flows

Tue, 21/01/2025 - 12:02
The structure and lifecycle of stratified mixing in forced shear flows

Our environment is shaped by stably stratified air and water masses and the turbulent mixing of heat and chemicals within them. This talk addresses the challenge of understanding and predicting the density-stratified turbulent mixing driven by shear instabilities at high Reynolds numbers (Re > 10^5). These shear instabilities are a key process in the turbulent energy cascade in the ocean, spanning a great range of scales, from coherent instabilities at kilometre scales to the smallest eddies at micrometre scales. We present observational data taken by collaborators from the Woods Hole Oceanographic Institution at the mouth of the Connecticut River, a shallow salt-wedge estuary. Multi-beam echo-sounding imagery provides access to the spatial structure and temporal evolution of the intense interfacial mixing with unprecedented detail. The data demonstrate that mixing occurs primarily by turbulence in the ‘braids’ connecting the ‘cores’ of Kelvin-Helmholtz billows, rather than within the cores themselves. This secondary braid turbulence appears to be continuously forced by the baroclinic generation of shear in the tilted braid. This finding challenges the prevailing paradigm built upon direct numerical simulations (DNS) at lower Reynolds and Prandtl numbers, where mixing tends to occur primarily by overturning in the billow cores. This distinction may represent a shift in our understanding of mixing in highly dissipative hotspots driven by large-scale shear — not only in estuaries but also in wind-driven surface currents and deep oceanic overflows.

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Fri 14 Feb 17:30: Epigenetics: A Code upon a Code?

Tue, 21/01/2025 - 08:05
Epigenetics: A Code upon a Code?

Abstract

On top of the heritable genetic code that is our DNA , sits another layer of information that influences our genes. Studying the properties and functions of this ‘epi-genetic’ information has revealed a whole new aspect of genome biology with implications for health and disease, providing compelling explanations for how we might respond to our environment, and making us consider whether DNA is the only code we transmit from one generation to the next.

In her lecture, Anne will consider the influence of epigenetics on our genes, share a few insights into how understanding epigenetics is contributing to modern medicine, and encourage us to question at least some of what we think we might know about epigenetics.

Biography

Professor Anne Ferguson-Smith is the Executive Chair of the Biotechnology and Biological Sciences Research Council (BBSRC). Before this appointment she served as Pro-Vice-Chancellor (Research and International Partnerships) at the University of Cambridge. A renowned mammalian developmental geneticist, genome biologist and epigeneticist, Professor Ferguson-Smith is the Balfour Professor of Genetics in the University of Cambridge’s Department of Genetics where she served as Head of Department from 2013-2020. She is also a Fellow of Darwin College.

At the University of Cambridge, Professor Ferguson-Smith leads a research group comprised of experimental and computational scientists. They focus on the epigenetic control of genome function, particularly on models of epigenetic inheritance with implications for health and disease. Committed to the training and professional development of new talent, her team’s current work includes investigating how genetic, epigenetic and environmental factors influence cellular and developmental processes.

In 2017, Anne was elected a Fellow of the Royal Society and in 2021 received their Buchanan Medal for her pioneering work on epigenetics. In 2023, she was named Commander of the British Empire (CBE) for her research contributions.

Photo – Dasha Tenditna

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Mon 17 Feb 13:00: Stratification and mixing regimes in the global coastal ocean: classifications and trends from models and observations

Mon, 20/01/2025 - 15:27
Stratification and mixing regimes in the global coastal ocean: classifications and trends from models and observations

Abstract not available

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Thu 20 Feb 11:30: TBC

Mon, 20/01/2025 - 08:57
TBC

Abstract not available

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Thu 27 Feb 11:30: TBC

Mon, 20/01/2025 - 08:53
TBC

Abstract not available

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