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1. VLMine: Long-Tail Data Mining with Vision Language Models

Author

Ye, Mao, Meyer, Gregory P., Zhang, Zaiwei, Park, Dennis, Mustikovela, Siva Karthik, Chai, Yuning, and Wolff, Eric M

Subjects
Computer Science - Computer Vision and Pattern Recognition, Computer Science - Artificial Intelligence
Abstract

Ensuring robust performance on long-tail examples is an important problem for many real-world applications of machine learning, such as autonomous driving. This work focuses on the problem of identifying rare examples within a corpus of unlabeled data. We propose a simple and scalable data mining approach that leverages the knowledge contained within a large vision language model (VLM). Our approach utilizes a VLM to summarize the content of an image into a set of keywords, and we identify rare examples based on keyword frequency. We find that the VLM offers a distinct signal for identifying long-tail examples when compared to conventional methods based on model uncertainty. Therefore, we propose a simple and general approach for integrating signals from multiple mining algorithms. We evaluate the proposed method on two diverse tasks: 2D image classification, in which inter-class variation is the primary source of data diversity, and on 3D object detection, where intra-class variation is the main concern. Furthermore, through the detection task, we demonstrate that the knowledge extracted from 2D images is transferable to the 3D domain. Our experiments consistently show large improvements (between 10\% and 50\%) over the baseline techniques on several representative benchmarks: ImageNet-LT, Places-LT, and the Waymo Open Dataset.

Published
2024

2. VLM-KD: Knowledge Distillation from VLM for Long-Tail Visual Recognition

Author

Zhang, Zaiwei, Meyer, Gregory P., Lu, Zhichao, Shrivastava, Ashish, Ravichandran, Avinash, and Wolff, Eric M.

Subjects
Computer Science - Computer Vision and Pattern Recognition
Abstract

For visual recognition, knowledge distillation typically involves transferring knowledge from a large, well-trained teacher model to a smaller student model. In this paper, we introduce an effective method to distill knowledge from an off-the-shelf vision-language model (VLM), demonstrating that it provides novel supervision in addition to those from a conventional vision-only teacher model. Our key technical contribution is the development of a framework that generates novel text supervision and distills free-form text into a vision encoder. We showcase the effectiveness of our approach, termed VLM-KD, across various benchmark datasets, showing that it surpasses several state-of-the-art long-tail visual classifiers. To our knowledge, this work is the first to utilize knowledge distillation with text supervision generated by an off-the-shelf VLM and apply it to vanilla randomly initialized vision encoders.

Published
2024

3. Cohere3D: Exploiting Temporal Coherence for Unsupervised Representation Learning of Vision-based Autonomous Driving

Author

Xie, Yichen, Chen, Hongge, Meyer, Gregory P., Lee, Yong Jae, Wolff, Eric M., Tomizuka, Masayoshi, Zhan, Wei, Chai, Yuning, and Huang, Xin

Subjects
Computer Science - Computer Vision and Pattern Recognition, Computer Science - Machine Learning
Abstract

Due to the lack of depth cues in images, multi-frame inputs are important for the success of vision-based perception, prediction, and planning in autonomous driving. Observations from different angles enable the recovery of 3D object states from 2D image inputs if we can identify the same instance in different input frames. However, the dynamic nature of autonomous driving scenes leads to significant changes in the appearance and shape of each instance captured by the camera at different time steps. To this end, we propose a novel contrastive learning algorithm, Cohere3D, to learn coherent instance representations in a long-term input sequence robust to the change in distance and perspective. The learned representation aids in instance-level correspondence across multiple input frames in downstream tasks. In the pretraining stage, the raw point clouds from LiDAR sensors are utilized to construct the long-term temporal correspondence for each instance, which serves as guidance for the extraction of instance-level representation from the vision-based bird's eye-view (BEV) feature map. Cohere3D encourages a consistent representation for the same instance at different frames but distinguishes between representations of different instances. We evaluate our algorithm by finetuning the pretrained model on various downstream perception, prediction, and planning tasks. Results show a notable improvement in both data efficiency and task performance.

Published
2024

6. Driving in Real Life with Inverse Reinforcement Learning

Author

Phan-Minh, Tung, Howington, Forbes, Chu, Ting-Sheng, Lee, Sang Uk, Tomov, Momchil S., Li, Nanxiang, Dicle, Caglayan, Findler, Samuel, Suarez-Ruiz, Francisco, Beaudoin, Robert, Yang, Bo, Omari, Sammy, and Wolff, Eric M.

Subjects
Computer Science - Robotics, Computer Science - Artificial Intelligence, Computer Science - Machine Learning, I.2.6, I.2.9
Abstract

In this paper, we introduce the first learning-based planner to drive a car in dense, urban traffic using Inverse Reinforcement Learning (IRL). Our planner, DriveIRL, generates a diverse set of trajectory proposals, filters these trajectories with a lightweight and interpretable safety filter, and then uses a learned model to score each remaining trajectory. The best trajectory is then tracked by the low-level controller of our self-driving vehicle. We train our trajectory scoring model on a 500+ hour real-world dataset of expert driving demonstrations in Las Vegas within the maximum entropy IRL framework. DriveIRL's benefits include: a simple design due to only learning the trajectory scoring function, relatively interpretable features, and strong real-world performance. We validated DriveIRL on the Las Vegas Strip and demonstrated fully autonomous driving in heavy traffic, including scenarios involving cut-ins, abrupt braking by the lead vehicle, and hotel pickup/dropoff zones. Our dataset will be made public to help further research in this area.

Published
2022

7. Multimodal Trajectory Prediction Conditioned on Lane-Graph Traversals

Author

Deo, Nachiket, Wolff, Eric M., and Beijbom, Oscar

Subjects
Computer Science - Computer Vision and Pattern Recognition, Computer Science - Robotics
Abstract

Accurately predicting the future motion of surrounding vehicles requires reasoning about the inherent uncertainty in driving behavior. This uncertainty can be loosely decoupled into lateral (e.g., keeping lane, turning) and longitudinal (e.g., accelerating, braking). We present a novel method that combines learned discrete policy rollouts with a focused decoder on subsets of the lane graph. The policy rollouts explore different goals given current observations, ensuring that the model captures lateral variability. Longitudinal variability is captured by our latent variable model decoder that is conditioned on various subsets of the lane graph. Our model achieves state-of-the-art performance on the nuScenes motion prediction dataset, and qualitatively demonstrates excellent scene compliance. Detailed ablations highlight the importance of the policy rollouts and the decoder architecture.

Published
2021

8. NuPlan: A closed-loop ML-based planning benchmark for autonomous vehicles

Author

Caesar, Holger, Kabzan, Juraj, Tan, Kok Seang, Fong, Whye Kit, Wolff, Eric, Lang, Alex, Fletcher, Luke, Beijbom, Oscar, and Omari, Sammy

Subjects
Computer Science - Computer Vision and Pattern Recognition
Abstract

In this work, we propose the world's first closed-loop ML-based planning benchmark for autonomous driving. While there is a growing body of ML-based motion planners, the lack of established datasets and metrics has limited the progress in this area. Existing benchmarks for autonomous vehicle motion prediction have focused on short-term motion forecasting, rather than long-term planning. This has led previous works to use open-loop evaluation with L2-based metrics, which are not suitable for fairly evaluating long-term planning. Our benchmark overcomes these limitations by introducing a large-scale driving dataset, lightweight closed-loop simulator, and motion-planning-specific metrics. We provide a high-quality dataset with 1500h of human driving data from 4 cities across the US and Asia with widely varying traffic patterns (Boston, Pittsburgh, Las Vegas and Singapore). We will provide a closed-loop simulation framework with reactive agents and provide a large set of both general and scenario-specific planning metrics. We plan to release the dataset at NeurIPS 2021 and organize benchmark challenges starting in early 2022., Comment: Minor updates to Related Work

Published
2021

10. Motion Prediction using Trajectory Sets and Self-Driving Domain Knowledge

Author

Boulton, Freddy A., Grigore, Elena Corina, and Wolff, Eric M.

Subjects
Computer Science - Machine Learning, Computer Science - Computer Vision and Pattern Recognition, Computer Science - Robotics, Statistics - Machine Learning, 68T07 (Primary) 68T40, 68T45 (Secondary), I.2.6, I.2.9, I.2.10, I.5
Abstract

Predicting the future motion of vehicles has been studied using various techniques, including stochastic policies, generative models, and regression. Recent work has shown that classification over a trajectory set, which approximates possible motions, achieves state-of-the-art performance and avoids issues like mode collapse. However, map information and the physical relationships between nearby trajectories is not fully exploited in this formulation. We build on classification-based approaches to motion prediction by adding an auxiliary loss that penalizes off-road predictions. This auxiliary loss can easily be pretrained using only map information (e.g., off-road area), which significantly improves performance on small datasets. We also investigate weighted cross-entropy losses to capture spatial-temporal relationships among trajectories. Our final contribution is a detailed comparison of classification and ordinal regression on two public self-driving datasets.

Published
2020

11. CoverNet: Multimodal Behavior Prediction using Trajectory Sets

Author

Phan-Minh, Tung, Grigore, Elena Corina, Boulton, Freddy A., Beijbom, Oscar, and Wolff, Eric M.

Subjects
Computer Science - Machine Learning, Computer Science - Robotics, Statistics - Machine Learning, 68, I.2
Abstract

We present CoverNet, a new method for multimodal, probabilistic trajectory prediction for urban driving. Previous work has employed a variety of methods, including multimodal regression, occupancy maps, and 1-step stochastic policies. We instead frame the trajectory prediction problem as classification over a diverse set of trajectories. The size of this set remains manageable due to the limited number of distinct actions that can be taken over a reasonable prediction horizon. We structure the trajectory set to a) ensure a desired level of coverage of the state space, and b) eliminate physically impossible trajectories. By dynamically generating trajectory sets based on the agent's current state, we can further improve our method's efficiency. We demonstrate our approach on public, real-world self-driving datasets, and show that it outperforms state-of-the-art methods.

Published
2019

15. Laser ablation inductively coupled plasma mass spectrometry measurements for high-resolution chemical ice core analyses with a first application to an ice core from Skytrain Ice Rise (Antarctica).

Author

Hoffmann, Helene, Day, Jason, Rhodes, Rachael H., Grieman, Mackenzie, Humby, Jack, Rowell, Isobel, Nehrbass-Ahles, Christoph, Mulvaney, Robert, Gibson, Sally, and Wolff, Eric

Abstract

Conventional methods of inorganic impurity analysis do not provide high enough depth resolution for many scientific questions in ice core science. In this study, we present a setup of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for high-resolution glacier ice impurity analysis to the sub-millimetre scale. This setup enables ice core chemical impurity analysis to a depth resolution of ∼182 µm while consuming only very small amounts of ice. The system performs simultaneous analysis of sodium, magnesium and aluminium incorporated in the ice matrix. In this case study within the framework of the WACSWAIN (WArm Climate Stability of the West Antarctic Ice Sheet in the last INterglacial) project, our method is applied to a selection of samples from the Skytrain ice core (West Antarctica) over a total length of 6.7 m consisting of about 130 single samples. The main goal of this study is to use the new LA-ICP-MS method to extract meaningful climate signals on a depth resolution level beyond the limits of continuous-flow analysis (CFA). A comparison between low-resolution CFA data and the high-resolution LA-ICP-MS data reveals generally good agreement on the decimetre scale. Stacking of parallel laser measurements together with frequency analysis is used to analyse the high-resolution LA-ICP-MS data at millimetre resolution. Spectral analysis reveals that despite effects of impurity accumulation along ice crystal grain boundaries, periodic concentration changes in the Skytrain ice core on the millimetre scale can be identified in ice from 26.8 ka (kiloyears before present, i.e. 1950 CE). These findings open new possibilities for climate data interpretation with respect to fast changes in the last glacial period and beyond, for example within the Beyond EPICA oldest-ice project. [ABSTRACT FROM AUTHOR]

Published
2024
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17. Reconciling ice core CO2 and land use change following New World-Old World contact

Author

King, Amy C.F., Bauska, Thomas K., Brook, Edward J., Kalk, Mike, Nehrbass-Ahles, Christoph, Wolff, Eric W., Strawson, Ivo, Rhodes, Rachael H., Osman, Matthew B., King, Amy C.F., Bauska, Thomas K., Brook, Edward J., Kalk, Mike, Nehrbass-Ahles, Christoph, Wolff, Eric W., Strawson, Ivo, Rhodes, Rachael H., and Osman, Matthew B.

Abstract

Ice core records of carbon dioxide (CO2) throughout the last 2000 years provide context for the unprecedented anthropogenic rise in atmospheric CO2 and insights into global carbon cycle dynamics. Yet the atmospheric history of CO2 remains uncertain in some time intervals. Here we present measurements of CO2 and methane (CH4) in the Skytrain ice core from 1450 to 1700 CE. Results suggest a sudden decrease in CO2 around 1610 CE in one widely used record may be an artefact of a small number of anomalously low values. Our analysis supports a more gradual decrease in CO2 of 0.5 ppm per decade from 1516 to 1670 CE, with an inferred land carbon sink of 2.6 PgC per decade. This corroborates modelled scenarios of large-scale reorganisation of land use in the Americas following New World-Old World contact, whereas a rapid decrease in CO2 at 1610 CE is incompatible with even the most extreme land-use change scenarios.

Published
2024

18. Melt-Affected Ice Cores for Polar Research in a Warming World

Author

Moser, Dorothea Elisabeth, Thomas, Elizabeth R., Nehrbass-Ahles, Christoph, Eichler, Anja, Wolff, Eric, Moser, Dorothea Elisabeth, Thomas, Elizabeth R., Nehrbass-Ahles, Christoph, Eichler, Anja, and Wolff, Eric

Abstract

Melting polar and alpine ice sheets in response to global warming pose ecological and societal risks but will also hamper our ability to reconstruct past climate and atmospheric composition across the globe. Since polar ice caps are crucial environmental archives but highly sensitive to ongoing climate warming, the Arctic and Antarctic research community is increasingly faced with melt-affected ice cores, which are already common in alpine settings of the lower latitudes. Here, we review the characteristics and effects of near-surface melting on ice-core records, focusing on a polar readership and making recommendations for melt-prone study regions. This review first covers melt layer formation, identification and quantification of melt, and structural characteristics of melt features. Subsequently, it discusses effects of melting on records of chemical impurities, i.e. major ions, trace elements, black carbon, and organic species as well as stable water isotopic signatures, gas records, and applications of melt layers as environmental proxies. Melting occurs during positive surface energy balance events, which are shaped by global to local meteorological forcing, regional orography, glacier surface conditions and subsurface characteristics. Meltwater flow ranges from homogeneous wetting to spatially heterogeneous preferential flow paths and is determined by temperature, thermal conductivity and stratigraphy of the snowpack. Melt layers and lenses are the most common consequent features in ice cores and are usually recorded manually or using line scanning. Chemical ice-core proxy records of water-soluble species are generally less preserved than insoluble particles such as black carbon or mineral dust due to their strong elution behaviour during percolation. However, high solubility in ice as observed for ions like F−, Cl−, NH+4 or ultra-trace elements can counteract the high mobility of these species due to burial in the ice interior. Stable water isotope records l

Published
2024

20. New estimates of sulfate diffusion rates in the EPICA Dome C ice core.

Author

Rhodes, Rachael H., Bollet-Quivogne, Yvan, Barnes, Piers, Severi, Mirko, and Wolff, Eric W.

Subjects
INTERGLACIALS, ANTARCTIC ice, ICE cores, GLACIATION, CRYSTAL grain boundaries
Abstract

To extract climatically relevant chemical signals from the deepest, oldest Antarctic ice, we must first investigate the degree to which chemical ions diffuse within solid ice. Volcanic sulfate peaks are an ideal target for such an investigation because they are high-amplitude, short-duration (∼3 years) events with a quasi-uniform structure. Here we present an analysis of the EPICA Dome C sulfate record over the last 450 kyr. We identify volcanic peaks and isolate them from the non-sea-salt sulfate background to reveal the effects of diffusion: amplitude damping and broadening of peaks in the time domain with increasing depth and age. Sulfate peak shape is also altered by the thinning of ice layers with depth that results from ice flow. Both processes must be simulated to derive effective diffusion rates. This is achieved by running a forward model to diffuse idealised sulfate peaks at different rates while also accounting for ice thinning. Our simulations suggest a median effective diffusion rate of sulfate ions of 2.4±1.7×10-7 m 2 yr -1 in Holocene ice, slightly faster than suggested by previous work. The effective diffusion rate observed in deeper ice is significantly lower, and Holocene ice shows the highest rate of the last 450 kyr. Beyond the Holocene, there is no systematic difference between the effective diffusion rates of glacial and interglacial periods despite variations in soluble ion concentrations, dust loading, and ice grain radii. Effective diffusion rates for 40 to 200 ka are relatively constant and of the order 1×10-8 m 2 yr -1. Our results suggest that the diffusion of sulfate ions within volcanic peaks is relatively fast initially, perhaps through an interconnected vein network, but slows significantly after 40 kyr. In the absence of clear evidence for a controlling influence of temperature on sulfate diffusivity with depth and age, we hypothesise that the rapid decrease in effective diffusion rate from the time of deposition to ice of 50 ka age may be due to a switch in the mechanism of diffusion resulting from the changing location of sulfate ions within the ice microstructure and/or interconnectedness of veins and grain boundaries. [ABSTRACT FROM AUTHOR]

Published
2024
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24. Laser Ablation – ICP-MS measurements for high resolution chemical ice core analyses with a first application to an ice core from Skytrain Ice Rise (Antarctica)

Author

Hoffmann, Helene, primary, Day, Jason, additional, Rhodes, Rachael, additional, Grieman, Mackenzie, additional, Humby, Jack, additional, Rowell, Isobel, additional, Nehrbass-Ahles, Christoph, additional, Mulvaney, Robert, additional, Gibson, Sally, additional, and Wolff, Eric, additional

Published
2024
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27. Methods for biogeochemical studies of sea ice: The state of the art, caveats, and recommendations

Author

Miller, Lisa A, Fripiat, Francois, Else, Brent GT, Bowman, Jeff S, Brown, Kristina A, Collins, R Eric, Ewert, Marcela, Fransson, Agneta, Gosselin, Michel, Lannuzel, Delphine, Meiners, Klaus M, Michel, Christine, Nishioka, Jun, Nomura, Daiki, Papadimitriou, Stathys, Russell, Lynn M, Sørensen, Lise Lotte, Thomas, David N, Tison, Jean-Louis, van Leeuwe, Maria A, Vancoppenolle, Martin, Wolff, Eric W, and Zhou, Jiayun

Subjects
Life Below Water
Abstract

Over the past two decades, with recognition that the ocean's sea-ice cover is neither insensitive to climate change nor a barrier to light and matter, research in sea-ice biogeochemistry has accelerated significantly, bringing together a multi-disciplinary community from a variety of fields. This disciplinary diversity has contributed a wide range of methodological techniques and approaches to sea-ice studies, complicating comparisons of the results and the development of conceptual and numerical models to describe the important biogeochemical processes occurring in sea ice. Almost all chemical elements, compounds, and biogeochemical processes relevant to Earth system science are measured in sea ice, with published methods available for determiningbiomass, pigments, net community production, primary production, bacterial activity, macronutrients, numerous natural and anthropogenic organic compounds, trace elements, reactive and inert gases, sulfur species, the carbon dioxide system parameters, stable isotopes, and water-ice-Atmosphere fluxes of gases, liquids, and solids. For most of these measurements, multiple sampling and processing techniques are available, but to date there has been little intercomparison or intercalibration between methods. In addition, researchers collect different types of ancillary data and document their samples differently, further confounding comparisons between studies. These problems are compounded by the heterogeneity of sea ice, in which even adjacent cores can have dramatically different biogeochemical compositions. We recommend that, in future investigations, researchers design their programs based on nested sampling patterns, collect a core suite of ancillary measurements, and employ a standard approach for sample identification and documentation. In addition, intercalibration exercises are most critically needed for measurements of biomass, primary production, nutrients, dissolved and particulate organic matter (including exopolymers), the CO2 system, air-ice gas fluxes, and aerosol production. We also encourage the development of in situ probes robust enough for long-Term deployment in sea ice, particularly for biological parameters, the CO2 system, and other gases.

Published
2015

29. Review article: Melt-affected ice cores for polar research in a warming world.

Author

Moser, Dorothea Elisabeth, Thomas, Elizabeth R., Nehrbass-Ahles, Christoph, Eichler, Anja, and Wolff, Eric

Subjects
ICE cores, ANTARCTIC ice, MELTWATER, GLOBAL warming, CONSCIOUSNESS raising, MINERAL dusts, GLACIAL melting, POLAR vortex
Abstract

Melting polar and alpine ice sheets in response to global warming pose ecological and societal risks but will also hamper our ability to reconstruct past climate and atmospheric composition across the globe. Since polar ice caps are crucial environmental archives but highly sensitive to ongoing climate warming, the Arctic and Antarctic research community is increasingly faced with melt-affected ice cores, which are already common in alpine settings of the lower latitudes. Here, we review the characteristics and effects of near-surface melting on ice-core records, focusing on a polar readership and making recommendations for melt-prone study regions. This review first covers melt layer formation, identification and quantification of melt, and structural characteristics of melt features. Subsequently, it discusses effects of melting on records of chemical impurities, i.e. major ions, trace elements, black carbon, and organic species as well as stable water isotopic signatures, gas records, and applications of melt layers as environmental proxies. Melting occurs during positive surface energy balance events, which are shaped by global to local meteorological forcing, regional orography, glacier surface conditions and subsurface characteristics. Meltwater flow ranges from homogeneous wetting to spatially heterogeneous preferential flow paths and is determined by temperature, thermal conductivity and stratigraphy of the snowpack. Melt layers and lenses are the most common consequent features in ice cores and are usually recorded manually or using line scanning. Chemical ice-core proxy records of water-soluble species are generally less preserved than insoluble particles such as black carbon or mineral dust due to their strong elution behaviour during percolation. However, high solubility in ice as observed for ions like F - , Cl - , NH 4+ or ultra-trace elements can counteract the high mobility of these species due to burial in the ice interior. Stable water isotope records like δ18 O are often preserved but appear smoothed if significant amounts of meltwater are involved. Melt-affected ice cores are further faced with questions about the permeability of the firn column for gas movement, and gas concentrations can be increased through dissolution and in situ production. Noble gas ratios can be useful tools for identifying melt-affected profile sections in deep ice. Despite challenges for ice-core climate reconstruction based on chemical records, melt layers are a proxy of warm temperatures above freezing, which is most sensitive in the dry snow and percolation zone. Bringing together insights from snow physics, firn hydrology, and ice-core proxy research, we aim to foster a more comprehensive understanding of ice cores as climate and environmental archives, provide a reference on how to approach melt-affected records, and raise awareness of the limitations and potential of melt layers in ice cores. [ABSTRACT FROM AUTHOR]

Published
2024
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30. TCT-424 In Vitro Investigation of Polymer Damage on Drug-Eluting Stents Resulting From Intravascular Lithotripsy

Author

Beatty, Brian, primary, Shin, Doosup, additional, Wolff, Eric, additional, Shearer, Mickey, additional, Sarah, Malik, additional, Singh, Mandeep, additional, Tsioulias, Anna, additional, Saggio, Gregory, additional, Shlofmitz, Evan, additional, Jeremias, Allen, additional, Maehara, Akiko, additional, Moses, Jeffrey, additional, Shlofmitz, Richard, additional, and Ali, Ziad, additional

Published
2023
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31. Lead, Follow, or Go Your Own Way: Empirical Evidence Against Leader-Follower Behavior in Electronic Markets

Author

Clay, Karen, Smith, Michael, and Wolff, Eric

Subjects
Computer Science - Computers and Society, K.4.m Miscellaneous
Abstract

Low search costs in Internet markets can be used by consumers to find low prices, but can also be used by retailers to monitor competitors' prices. This price monitoring can lead to price matching, resulting in dampened price competition and higher prices in some cases. This paper analyzes price data for 316 bestselling, computer, and random book titles gathered from 32 retailers between August 1999 and January 2000. In contrast to previous studies we find no evidence of leader-follow behavior for the vast majority of retailers we study. Further, the few cases of leader-follow behavior we observe seem to be associated with managerial convenience as opposed to anti-competitive behavior. We offer a methodology that can be used by future academic researchers or government regulators to check for anti-competitive price matching behavior in future time periods or in additional product categories., Comment: 29 TPRC Conference, 2001

Published
2001

41. Reconciling ice core CO2 and land-use change following New World-Old World contact.

Author

King, Amy C. F., Bauska, Thomas K., Brook, Edward. J., Kalk, Mike, Nehrbass-Ahles, Christoph, Wolff, Eric. W., Strawson, Ivo, Rhodes, Rachael H., and Osman, Matthew B.

Subjects
ICE cores, CARBON cycle, ATMOSPHERIC carbon dioxide, CARBON dioxide
Abstract

Ice core records of carbon dioxide (CO2) throughout the last 2000 years provide context for the unprecedented anthropogenic rise in atmospheric CO2 and insights into global carbon cycle dynamics. Yet the atmospheric history of CO2 remains uncertain in some time intervals. Here we present measurements of CO2 and methane (CH4) in the Skytrain ice core from 1450 to 1700 CE. Results suggest a sudden decrease in CO2 around 1610 CE in one widely used record may be an artefact of a small number of anomalously low values. Our analysis supports a more gradual decrease in CO2 of 0.5 ppm per decade from 1516 to 1670 CE, with an inferred land carbon sink of 2.6 PgC per decade. This corroborates modelled scenarios of large-scale reorganisation of land use in the Americas following New World-Old World contact, whereas a rapid decrease in CO2 at 1610 CE is incompatible with even the most extreme land-use change scenarios. Ice core records of gradually declining atmospheric carbon dioxide (CO2) for the period 1450–1700 CE support modelled scenarios of large-scale reorganisation of land use in the Americas following New World-Old World contact. [ABSTRACT FROM AUTHOR]

Published
2024
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42. Laser Ablation - ICP-MS measurements for high resolution chemical ice core analyses with a first application to an ice core from Skytrain Ice Rise (Antarctica).

Author

Hoffmann, Helene, Day, Jason, Rhodes, Rachael, Grieman, Mackenzie, Humby, Jack, Rowell, Isobel, Nehrbass-Ahles, Christoph, Mulvaney, Robert, Gibson, Sally, and Wolff, Eric

Abstract

For many ice core related scientific questions, like the analysis of fast changing climate signals, the depth resolution of conventional methods of analysis is not sufficient. In this study we present a setup of Laser Ablation Inductively Coupled Plasma - Mass Spectrometry (LA-ICP-MS) for high resolution glacier ice impurity analysis to the sub-millimetre scale. This setup enables chemical impurity ice core analysis to a depth resolution of ~ 80 µm while consuming only minimal amounts of ice. The system was used for simultaneous analysis of sodium, magnesium and aluminium incorporated in the ice structure. In a first case study within the framework of the WACSWAIN (WArm Climate Stability of the West Antarctic ice sheet in the last INterglacial) project, the method was applied to a selection of samples from Skytrain ice core (West Antarctica), on a total length of 6.7 m consisting of about 130 single samples. The main goal of this study was to use the new LA-ICP-MS method to extract meaningful climate signals on a depth resolution level beyond the limits of Continuous Flow Analysis (CFA). A comparison between low resolution CFA data and the high resolution LA-ICP-MS data reveals generally good agreement on the decimetre scale. Stacking of parallel laser measurements together with frequency analysis is used to analyse the high resolution LA-ICP-MS data on the millimetre scale. Spectral analysis revealed that despite effects of impurity accumulation in ice crystal grain boundaries, periodic concentration changes in the Skytrain ice core on the millimetre scale can be identified in ice from 26 ka BP (kilo years before present; 1950 CE) and also from the Last Interglacial (LIG). These findings can open new possibilities for climate data interpretation with respect to fast changes in the last glacial and beyond. [ABSTRACT FROM AUTHOR]

Published
2024
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43. Personal Jurisdiction And Foreign Corporation Registration Statutes: A Purple Haze, But The Sky Is Not Falling

Author

Wolff, Eric B.

Subjects
United States. Supreme Court -- Cases, Judicial opinions -- Cases, Foreign corporations -- Cases, Personal jurisdiction -- Cases, Due process of law -- Cases, Company legal issue, Business, international
Abstract

The U.S. Supreme Court has held--by a 5-4 margin--that it did not violate due process for a Pennsylvania court to exercise jurisdiction over an asbestos case with no connection to [...]

Published
2023

45. Palaeoclimate constraints on the impact of 2 °C anthropogenic warming and beyond

Author

Fischer, Hubertus, Meissner, Katrin J., Mix, Alan C., Abram, Nerilie J., Austermann, Jacqueline, Brovkin, Victor, Capron, Emilie, Colombaroli, Daniele, Daniau, Anne-Laure, Dyez, Kelsey A., Felis, Thomas, Finkelstein, Sarah A., Jaccard, Samuel L., McClymont, Erin L., Rovere, Alessio, Sutter, Johannes, Wolff, Eric W., Affolter, Stéphane, Bakker, Pepijn, Ballesteros-Cánovas, Juan Antonio, Barbante, Carlo, Caley, Thibaut, Carlson, Anders E., Churakova (Sidorova), Olga, Cortese, Giuseppe, Cumming, Brian F., Davis, Basil A. S., de Vernal, Anne, Emile-Geay, Julien, Fritz, Sherilyn C., Gierz, Paul, Gottschalk, Julia, Holloway, Max D., Joos, Fortunat, Kucera, Michal, Loutre, Marie-France, Lunt, Daniel J., Marcisz, Katarzyna, Marlon, Jennifer R., Martinez, Philippe, Masson-Delmotte, Valerie, Nehrbass-Ahles, Christoph, Otto-Bliesner, Bette L., Raible, Christoph C., Risebrobakken, Bjørg, Sánchez Goñi, María F., Arrigo, Jennifer Saleem, Sarnthein, Michael, Sjolte, Jesper, Stocker, Thomas F., Velasquez Alvárez, Patricio A., Tinner, Willy, Valdes, Paul J., Vogel, Hendrik, Wanner, Heinz, Yan, Qing, Yu, Zicheng, Ziegler, Martin, and Zhou, Liping

Published
2018
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46. The ST22 chronology for the Skytrain Ice Rise ice core – Part 1: A stratigraphic chronology of the last 2000 years

Author

Hoffmann, Helene M., Grieman, Mackenzie M., King, Amy C. F., Epifanio, Jenna A., Martin, Kaden, Vladimirova, Diana, Pryer, Helena V., Doyle, Emily, Schmidt, Axel, Humby, Jack D., Rowell, Isobel F., Nehrbass-Ahles, Christoph, Thomas, Elizabeth R., Mulvaney, Robert, Wolff, Eric W., Hoffmann, HM [0000-0002-7527-5880], Grieman, MM [0000-0001-9610-7141], King, ACF [0000-0002-1285-7568], Epifanio, JA [0000-0002-0430-5720], Vladimirova, D [0000-0002-1678-0174], Rowell, IF [0000-0003-0238-2340], Nehrbass-Ahles, C [0000-0002-4009-4633], Thomas, ER [0000-0002-3010-6493], Mulvaney, R [0000-0002-5372-8148], Wolff, EW [0000-0002-5914-8531], and Apollo - University of Cambridge Repository

Subjects
13 Climate Action, Global and Planetary Change, Stratigraphy, Paleontology, 37 Earth Sciences, 3705 Geology, 3709 Physical Geography and Environmental Geoscience
Abstract

A new ice core was drilled in West Antarctica on Skytrain Ice Rise in field season 2018/2019. This 651 m ice core is one of the main targets of the WACSWAIN (WArm Climate Stability of the West Antarctic ice sheet in the last INterglacial) project. A present-day accumulation rate of 13.5 cm w.e. yr−1 was derived. Although the project mainly aims to investigate the last interglacial (115–130 ka), a robust chronology period covering the recent past is needed to constrain the age models for the deepest ice. Additionally, this time period is important for understanding current climatic changes in the West Antarctic region. Here, we present a stratigraphic chronology for the top 184.14 m of the Skytrain ice core based on absolute age tie points interpolated using annual layer counting encompassing the last 2000 years of climate history. Together with a model-based depth–age relationship of the deeper part of the ice core, this will form the ST22 chronology. The chemical composition, dust content, liquid conductivity, water isotope concentration and methane content of the whole core was analysed via continuous flow analysis (CFA) at the British Antarctic Survey. Annual layer counting was performed by manual counting of seasonal variations in mainly the sodium and calcium records. This counted chronology was informed and anchored by absolute age tie points, namely, the tritium peak (1965 CE) and six volcanic eruptions. Methane concentration variations were used to further constrain the counting error. A minimal error of ±1 year at the tie points was derived, accumulating to ± 5 %–10 % of the age in the unconstrained sections between tie points. This level of accuracy enables data interpretation on at least decadal timescales and provides a solid base for the dating of deeper ice, which is the second part of the chronology.

Published
2022
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47. The ST22 chronology for the Skytrain Ice Rise ice core – Part 2: An age model to the last interglacial and disturbed deep stratigraphy

Author

Mulvaney, Robert, primary, Wolff, Eric W., additional, Grieman, Mackenzie M., additional, Hoffmann, Helene H., additional, Humby, Jack D., additional, Nehrbass-Ahles, Christoph, additional, Rhodes, Rachael H., additional, Rowell, Isobel F., additional, Parrenin, Frédéric, additional, Schmidely, Loïc, additional, Fischer, Hubertus, additional, Stocker, Thomas F., additional, Christl, Marcus, additional, Muscheler, Raimund, additional, Landais, Amaelle, additional, and Prié, Frédéric, additional

Published
2023
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49. A 1.5-million-year record of orbital and millennial climate variability in the North Atlantic

Author

Stratigraphy and paleontology, Stratigraphy & paleontology, Hodell, David A., Crowhurst, Simon J., Lourens, Lucas, Margari, Vasiliki, Nicolson, John, Rolfe, James E., Skinner, Luke C., Thomas, Nicola C., Tzedakis, Polychronis C., Mleneck-Vautravers, Maryline J., Wolff, Eric W., Stratigraphy and paleontology, Stratigraphy & paleontology, Hodell, David A., Crowhurst, Simon J., Lourens, Lucas, Margari, Vasiliki, Nicolson, John, Rolfe, James E., Skinner, Luke C., Thomas, Nicola C., Tzedakis, Polychronis C., Mleneck-Vautravers, Maryline J., and Wolff, Eric W.

Published
2023

50. Viability of chemical and water isotope ratio measurements of RAID ice chippings from Antarctica

Author

Rowell, Isobel F., Mulvaney, Robert, Rix, Julius, Tetzner, Dieter R., Wolff, Eric W., Rowell, Isobel F., Mulvaney, Robert, Rix, Julius, Tetzner, Dieter R., and Wolff, Eric W.

Abstract

The British Antarctic Survey's (BAS) Rapid Access Isotope Drill (RAID), designed for rapid drilling to survey prospective ice core sites, has been deployed at multiple Antarctic locations over 6 years. This drilling method creates ice chippings that can be discretely sampled and analysed for their chemical and water isotopic composition. Ice sampling methods have evolved since the first uses of the BAS RAID, enabling a more quantifiable sample resolution. Here, we show that water isotope records obtained from RAID ice are comparable to those of equivalent depth resolution from proximal ice cores. Records of chemical impurities also show good agreement with nearby cores. Our findings suggest that the RAID is suitable for both chemical and isotopic reconnaissance of drilling sites. Residual contamination of certain ions is discussed, with proposed design changes to avoid this issue with future use.

Published
2023

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