About

Dr. Richard Alley is an Evan Pugh University Professor of Geosciences at Penn State. He earned his Ph.D. in Geology from Wisconsin-Madison in 1987. His research focuses on studying the great ice sheets to help predict future changes in climate and sea level. Dr. Alley has made multiple trips to Antarctica, Greenland, Alaska, and other locations to conduct his research. He has been honored for his contributions to research, including election to the US National Academy of Sciences and Foreign Membership in the Royal Society. Dr. Alley participated in the UN Intergovernmental Panel on Climate Change, which was awarded the Nobel Peace Prize in 2007, and has provided advice to numerous government officials across different administrations. He has authored or coauthored over 300 refereed scientific papers and is known for his work on climate change, ice cores, and sea level rise. Additionally, he has been a presenter for the PBS miniseries 'Earth: The Operators’ Manual' and authored the book 'The Two-Mile Time Machine'.

Research topics

• Oceanography
• Geology
• Climatology
• Geography
• Geomorphology
• Physical geography
• Environmental science
• Remote sensing
• Atmospheric sciences
• Physics
• Paleontology

Selected publications

• Heterogeneous subglacial sediments beneath Thwaites Glacier, West Antarctica, inferred from seismic data

  2026-04-09 · 1 citations

  articleOpen access

  Constraining the properties of subglacial materials is key to the accurate parameterisation of glacial slip in ice sheet models and is therefore important for accurate projections of sea level rise. The bed of Thwaites Glacier, West Antarctica, is particularly important because Thwaites is key to the stability of the West Antarctic Ice Sheet. We report the results of active-source seismic surveys undertaken during the 2023/24 Antarctic field season, immediately upstream of the subglacial ridge known as Ghost ridge. These include a 14.4 km profile of normal-incidence data and wide angle data over sections totalling ∼ 5 km. Estimation of basal acoustic impedance reveals that the bed in this region is composed of sediments, with regions of dilatant sediments and regions of stiffer sediments present. Amplitude-versus-angle (AVA) analysis of wide angle data supports this interpretation, with soft bed regions displaying high Poisson’s ratios (> 0.45). We image bedforms which are interpreted as sedimentary depositional bedforms, one of which we interpret as a crag and tail formation, and the other of which appears as a sedimentary tail emerging from rolling topography upstream. The tails of these features are probably composed of dilatant till. We apply Viscous Grain Shearing (VGS) theory to results obtained from AVA analysis to constrain the porosity and effective pressure of the subglacial sediments. VGS analysis suggests that the changes in reflectivity along our seismic profile may be primarily controlled by changes in effective pressure at the ice base rather than porosity.

  PublisherDOI

• Rift‐Related Sedimentary Basin and Deeper‐Seated Mafic Intrusions Modeled Beneath Thwaites Glacier, West Antarctica: Influence on Glacier Dynamics

  Journal of Geophysical Research Solid Earth · 2025-09-26 · 1 citations

  articleOpen access

  Abstract Thwaites Glacier in West Antarctica has been identified as a route to destabilization of the whole West Antarctic Ice Sheet, potentially leading to several meters of sea‐level rise. However, future evolution of Thwaites Glacier remains uncertain due to a lack of detailed knowledge about its basal boundary that will affect how its retreat proceeds. Here we aim to improve understanding of the basal boundary in the lower part of Thwaites Glacier by modeling the crustal structures that are related to the bed‐type distribution and therefore influence the basal slip. We combine long‐offset seismic, and gravity‐ and magnetic‐anomaly data to model the crustal structures along two 120 km lines roughly parallel to ice flow. We find a sedimentary basin 40 km in length in the along‐flow direction, with a maximum thickness of 1.7 0.2 km, and two mafic intrusions at 5–10 km depth that vary in maximum thickness between 3.8 and 8.6 km. The sedimentary basin and major mafic intrusions we modeled are likely related to the multi‐stage tectonic evolution of the West Antarctic Rift System. Thwaites Glacier flows across a tectonic boundary within our study site, indicating it flows across tectonically formed structures. The varying geology and resulting variations in bed types demonstrate the influence of tectonics on Thwaites Glacier dynamics.

  PublisherOA PDFDOI

• Recent Variability in Fracture Characteristics and Ice Flow of Thwaites Ice Shelf, West Antarctica

  Journal of Geophysical Research Earth Surface · 2025-05-01 · 4 citations

  articleOpen access

  Abstract The rapidly changing Thwaites Ice Shelf is crucial for understanding ice‐shelf dynamical processes and their implications for sea‐level rise from Antarctica. Fractures, particularly their vertical structure, are key to ice‐shelf structural integrity but remain poorly measured. To address this, we developed a fracture‐characterization workflow using ICESat‐2 ATL03 geolocated photon heights, producing the first time‐series vertical measurements of fractures across Thwaites from 2018 to 2024. We introduced the fracture depth/freeboard ratio as a normalized metric to quantify vertical fracture extent, serving as an indicator of structural damage. This metric enabled us to track fracture evolution in both the eastern ice shelf and western glacier tongue. In the eastern section, fracturing intensified along the northwestern shear zone and near the grounding line, in a positive feedback loop between enhanced fracturing and accelerated flow. The western section maintained an active rift formation zone about 15 km downstream of the historical grounding line. Flow velocity changes in this section were primarily confined to the unconstrained downstream portion, exhibiting an overall deceleration trend, while the upstream area remained stable. This contrast highlights the role of lateral margin conditions in governing ice‐shelf fracture and flow behavior. Changes in the eastern section showed some correspondence with warm winter air temperatures, reduced sea ice, and persistent warm ocean anomalies at shallower depths, suggesting that atmosphere‐sea ice‐ocean interactions influence ice‐shelf structural integrity through basal processes. Future research should integrate satellite‐derived fracture observations with numerical models of ice fracture and flow to better capture the dynamics of ice‐shelf weakening and retreat.

  PublisherOA PDFDOI

• Uncovering Basal Sliding Mechanisms at the Grounding Line of Rutford Ice Stream, West Antarctica: Big Data Analysis of Sticky Spots

  2025-02-06

  preprintOpen access
  PublisherOA PDFDOI

• Characteristics, origin and significance of chessboard subgrain boundaries in the WAIS divide ice core

  Annals of Glaciology · 2025-01-01

  articleOpen access

  Abstract Observation of thin sections of the WAIS (West Antarctic Ice Sheet) Divide ice core in cross-polarized light reveals a wealth of microstructures and textural characteristics indicative of strain and recovery in an anisotropic crystalline substance undergoing high-temperature plastic deformation. The appearance of abundant subgrain domains—relatively strain-free regions inside crystals (grains) surrounded by walls of dislocations across which small structural orientation changes occur—is particularly noticeable in the depth range associated with the brittle ice (∼650–1300 m). Here we describe a subgrain texture, not previously reported in ice, that resembles chessboard-pattern subgrains in β-quartz. This chessboard texture at WAIS Divide is strongly associated with the presence of bubbles. We hypothesize that chessboard-subgrain development may affect grain-size evolution, the fracture of ice cores recovered from the brittle ice zone and perhaps grain-boundary sliding as well.

  PublisherOA PDFDOI

• Drivers of global glacial erosion rates

  Nature Geoscience · 2025-08-01 · 4 citations

  articleOpen accessSenior author

  Glacial erosion must be quantified to better constrain numerous geomorphic and orogenic processes; however, accurate models of glacial erosion have been limited by sparse data. Here we use machine learning tools to develop equations that integrate glacial erosion and glaciological, topoclimatic and geological variables based on a global-scale synthesis of 181 contemporary glacier-derived erosion rates. The results reveal environment-specific erosion rate equations for surge-type, marine- and land-terminating glacial settings. We demonstrate that glacial velocity is not the most statistically important predictor of glacial erosion in any environment. Instead, an improved prediction of glacial erosion is attained when velocity is considered with additional glaciological, topoclimatic and geological variables, with the most dominant influences exhibited by precipitation, glacial elevation, length, latitude and the underlying geology. Using these equations, we estimate erosion rates for 85% of contemporary glaciers, with 99% eroding between 0.02 and 2.68 mm yr−1. Our results suggest a need to adjust how we predict or hindcast glacial erosion rates and highlight their sensitivity not only to changes in glacial sliding velocity but also to additional glaciological, topoclimatic and geological influences. Considering glaciological, topoclimatic and geological variables in addition to glacial velocity improves the prediction of glacial erosion rates according to a machine learning-based global analysis.

  PublisherOA PDFDOI

• Evolution of sub-ice-shelf channels reveals changes in ocean-driven melt in West Antarctica

  Journal of Glaciology · 2024-01-01 · 13 citations

  articleOpen access

  Abstract Basal channels, which are troughs carved into the undersides of ice shelves by buoyant plumes of water, are modulators of ice-shelf basal melt and structural stability. In this study, we track the evolution of 12 large basal channels beneath ice shelves of the Amundsen and Bellingshausen seas region in West Antarctica using the Landsat record since its start in the 1970s through 2020. We observe examples of channel growth, interactions with ice-shelf features, and systematic changes in sinuosity that give insight into the life cycles of basal channels. We use the last two decades of the record, combined with contemporary ice-flow velocity datasets, to separate channel-path evolution into components related to advection by ice flow and those controlled by other forcings, such as ocean melt or surface accumulation. Our results show that ice-flow-independent lateral channel migration is overwhelmingly to the left when viewed down-flow, suggesting that it is dominated by Coriolis-influenced ocean melt. By applying a model of channel-path evolution dominantly controlled by ice flow and ocean melt, we show that the majority of channels surveyed exhibit non-steady behavior that serves as a novel proxy for increased ocean forcing in West Antarctica starting at least in the early 1970s.

  PublisherOA PDFDOI

• Icequake insights on transient glacier slip mechanics near channelized subglacial drainage

  Earth and Planetary Science Letters · 2024-01-11 · 6 citations

  articleOpen access
  PublisherOA PDFDOI

• A Novel Deep Learning-Based Approach for Rift and Iceberg Recognition From ICESat-2 Data

  IEEE Transactions on Geoscience and Remote Sensing · 2024-01-01 · 3 citations

  article

  The knowledge of rifts and icebergs in Antarctica is imperative for understanding drivers and mechanisms controlling ice-shelf retreat. The description of their 3-D structural features has been challenging before the recent launch of the Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2), whose goal is to collect high-resolution elevation measurements using a photon-counting laser altimeter system. The great advancements of deep learning in multifeature characterization enable the recognition of rifts and icebergs from the Global Geolocated Photon Data (ATL03) product. Considering the insufficient 3-D information on rifts and icebergs at an extended spatiotemporal scale, we propose a novel deep learning-based approach to recognize rifts and icebergs from ATL03 data. First, ATL03 data are converted into three feature spaces, including 3-D point clouds, 2-D images, and 2-D graphs. Second, we construct a scene classification network for scene label prediction. This model builds three deep neural networks (DNNs) to separately encode three feature spaces, simultaneously extracting 3-D and 2-D morphological features and topological features from ATL03 data. These heterogeneous features are further integrated through a feature fusion layer. Finally, we implement a presegmentation algorithm to segment unlabeled ATL03 data into separate scenes and use a trained classifier to predict scene labels. Case studies on Antarctic ice shelves are conducted to validate the effectiveness of the proposed approach in terms of performance and generalization capabilities.

  PublisherDOI

• Key Findings and Recommendations

  2024-01-01

  other1st authorCorresponding

  Paleoclimatic data provide a highly informative if incomplete history of Arctic climate. Temperature history is especially well recorded, and it commonly allows researchers to accurately reconstruct changes and rates of changes for particular seasons. Precipitation (rain or snow) and the extent of ice on land and sea are some of the many other climate variables that have also been reconstructed. The data also provide insight into the histories of many possible causes of the climate changes and feedback processes that amplify or reduce the resulting changes. Comparing climate with possible causes allows scientists to generate and test hypotheses, and those hypotheses then become the basis for projections of future changes. Arctic data show changes on numerous time scales and indicate many causes and important feedback processes. Changes in greenhouse gases appear to have been especially important in causing climate changes (Chapter 2, section 2.4; Chapter 3, sections 3.4.1 and 3.4.4; Chapter 4, sections 4.4.1 and 4.4.2). Global climate changes have been notably amplified in the Arctic (Chapter 3, section 3.5), and warmer times have melted ice on land and sea (Chapter 6). Statistically valid confidence levels often can be attached to scientific findings, but those confidence levels commonly require many independent samples from a large population. Such a standard can be applied to paleoclimatic data in only some cases, whereas in other cases the necessary archives or interpretative tools are not available. However, expert judgment can also be used to assess confidence. The key findings here cannot all be evaluated rigorously using parametric statistics, but on the basis of assessment by the authors, all of the key findings are at least “likely” as used by the Intergovernmental Panel on Climate Change (more than 66% chance of being correct); the authors believe that the most of the findings are “very likely” (more than a 90% chance of being correct).

  PublisherDOI

Recent grants

• Collaborative Research: Physical Properties of the WAIS Divide Deep Core

  NSF · $564k · 2006–2012

• Collaborative Research: Continued Study of Physical Properties of the WAIS Divide Deep Core

  NSF · $428k · 2011–2016

• Climate History and Flow Processes from Physical Analyses of the SPICECORE South Pole Ice Core

  NSF · $200k · 2016–2020

• Collaborative Research: A synthesis of rapid meltwater and ice discharge changes: large forcings from the ice with impacts on global sea level and North Atlantic freshwater budgets

  NSF · $194k · 2005–2010

• Development of a Viscoelastic Ice-flow Model for Process-based Prediction of Ice-Sheet Evolution

  NSF · $295k · 2009–2013

Frequent coauthors

• S. Anandakrishnan

  Pennsylvania State University

  218 shared

• B. R. Parizek

  Pennsylvania State University

  105 shared

• K. C. Taylor

  Nevada System of Higher Education

  87 shared

• Knut Christianson

  University of Washington

  86 shared

• Anthony J. Gow

  80 shared

• D. A. Meese

  University of Maine

  80 shared

• Ian Joughin

  Johns Hopkins University Applied Physics Laboratory

  78 shared

• Pieter Meiert Grootes

  Kiel University

  74 shared

Education

• Ph.D., Glaciology

  University of Wisconsin-Madison

  1983

• M.S., Glaciology

  University of Wisconsin-Madison

  1979

• B.S., Geology

  California Institute of Technology

  1977

Awards & honors

• Election to the US National Academy of Sciences
• Foreign Membership in the Royal Society
• Co-recipient of the 2007 Nobel Peace Prize (as part of the U…