My research program aims to determine how ice sheets flow and fall apart. Understanding ice sheet dynamics on Earth is critical for the prediction of past and future global ice volumes, which have direct implications for global sea level. At present, the question that drives our research is: How does ice-sheet melting modulate ice-sheet flow? To approach this question, we pair geophysical observations with time-dependent inverse methods and computational modeling. We investigate Greenland and Antarctic ice sheet, ice shelf, and outlet glacier flow dynamics to better understand the physical mechanisms that destabilize ice sheets with increased surface meltwater production in our warming climate.
18-month Postdoctoral Research Position: With an anticipated start date in late 2023 or early 2024, the post holder will be responsible for carrying out research on numerical modelling of subglacial hydrology within the research group funded by NERC award: “NSFGEO-NERC: Understanding surface-to-bed meltwater pathways across the Greenland Ice Sheet using machine-learning and physics-based models.” The post holder will report to Laura Stevens (Earth Sciences) and Prof. Ian Hewitt (Mathematical Institute), and also work with international collaborators on the project located at Stanford and Kansas Universities. The job description and selection criteria can be found here (see PDF linked at bottom of page). If you have questions about the project, please get in touch via e-mail prior to submitting an application. Application closing date: 25 September 2023 !
Supraglacial lake on the western margin of the Greenland Ice Sheet (L. Stevens).
Current research projects include:
Understanding surface-to-bed meltwater pathways across the Greenland Ice Sheet using machine-learning and physics-based models
Jointly supported by the US NSF and UK NERC, this project will begin in September 2023 and aims to better understand surface-to-bed meltwater pathways across the entire Greenland Ice Sheet using machine-learning and physics-based models. The three-year project will use a combination of remote-sensing observations, deep learning, and physics-based models with aims to: (1) detect continent-wide surface fractures, moulins and supraglacial lake drainage events within satellite imagery; (2) determine the ice-sheet conditions required to trigger supraglacial lake drainage via hydrofracture; and (3) model the impact of supraglacial lake drainage events on ice-flow dynamics at a regional scale. Lead by Prof. Ching-Yao Lai (Princeton U.), additional collaborators include Profs. Leigh Stearns (U. Kansas) and Ian Hewitt (U. Oxford Mathematical Institute). Previous work that motivates this proposal is published in Lai et al. (2021) and Stevens et al. (2015; 2018) listed below.
Greenland Ice Sheet dynamic response to the inland expansion of a hydrologically active ice-sheet bed.
This project combines on-ice geodetic and radar observations with geophysical inverse and forward modeling techniques to investigate stress transmission between neighboring supraglacial lakes and moulins on the western margin of the Greenland Ice Sheet. Field observations of ice-sheet surface and englacial deformation will be collected over a 16-month period from May 2022 through August 2023. Collaborators include Drs. Meredith Nettles, Jonathan Kingslake, and Stacy Larochelle (Columbia University) and Marianne Okal (UNAVCO, Inc.).
Antarctic ice-shelf instability caused by active surface meltwater production, movement, ponding, and hydro-fracture.
Funded by NSFGEO–NERC, this project combines field observations, numerical modeling, and remote sensing techniques to better understand ice-shelf flexure and fracture due to surface meltwater loading. Field observations of ice-shelf surface height, local weather conditions, and water body depths are currently being collected on the George VIth Ice Shelf, Antarctic Peninsula through February 2023. This project is jointly supported by the US NSF and UK NERC, with field support provided by the British Antarctic Survey in coordination with the United States Antarctic Program. Collaborators include Drs. Alison Banwell (University of Colorado Boulder), Rebecca Dell (University of Cambridge), Douglas MacAyeal (University of Chicago), and Ian Willis (University of Cambridge).
Velocity fluctuations driven by surface melt and lake drainage at Helheim Glacier, East Greenland.
Investigating dynamics at the ice-ocean boundary brings together researchers in seismology, geodesy, applied mathematics, and oceanography. In my postdoctoral research supported by the Lamont-Doherty Earth Observatory, we worked to mechanistically understand tidally and atmospherically driven tidewater glacier flow of Helheim Glacier, one of Greenland’s fastest outlet glaciers. Through stochastic analysis of geodetic, environmental, and oceanographic observations, we characterized glacier-wide diurnal velocity variations and the glacier’s flow response to a rapid lake-drainage event. This work is published in Stevens et al. (2021) and Stevens et al. (2022) listed below.
View Selected Publications
- Stevens, L.A., Nettles, M., Davis, J.L., Creyts, T.C., Kingslake, J., Hewitt, I.J., and A. Stubblefield (2022). Tidewater-glacier response to supraglacial lake drainage. Nature Communications, 13:6065. doi:10.1038/s41467-022-33763-2.
- Zhang, H., Davis, T., Katz, R.F., Stevens, L.A., and D. May (2022). Basal hydrofractures near sticky patches. Journal of Glaciology, 1-12. doi:10.1017/jog.2022.75.
- Stevens, L.A., Nettles, M., Davis, J.L., Creyts, T.C., Kingslake, J., Ahlstrøm, A.P., and T.B. Larsen (2021). Helheim Glacier diurnal velocity fluctuations driven by surface melt forcing. Journal of Glaciology, 1-13. doi:10.1017/jog.2021.74.
- Lai, C.-Y., Stevens, L.A., Chase, D.L., Creyts, T.C., Behn, M.D., Das, S.B., and H.A. Stone (2021). Hydraulic transmissivity inferred from ice-sheet relaxation fol- lowing Greenland supraglacial lake drainages. Nature Communications, 12:3955. doi:10.1038/s41467-021-24186-6.
- Stevens, L.A., Hewitt, I., Das, S.B., Behn, M.D. (2018). Relationship between Greenland Ice Sheet surface speed and modeled eﬀective pressure. Journal of Geophysical Research: Earth Surface, 123. doi:10.1029/2017JF004581.
- Stevens, L.A., Behn, M.D., Das, S.B., Joughin, I., Noel, B. P. Y., van den Broeke, M., and T. Herring (2016). Greenland Ice Sheet ﬂow response to runoﬀ variability. Geophysical Research Letters, 43:11,295–11,303. doi:10.1002/2016GL070414.
- Stevens, L.A., Straneo, F., Das, S.B., Plueddemann, A.J., Kukulya, A.L., and M. Morlighem (2016). Linking glacially modiﬁed waters to catchment-scale subglacial discharge using autonomous underwater vehicle observations. The Cryosphere, 10:417–432. doi:10.5194/tc-10-417-2016.
- Stevens, L.A., Behn, M.D., McGuire, J.J., Das, S.B., Joughin, I., Herring, T., Shean, D.E., and M.A. King (2015). Greenland supraglacial lake drainages triggered by hydrologically induced basal slip. Nature, 522:73–76. doi:10.1038/nature14480.
View Extended Publications
- Wearing, M.G., Stevens, L.A., Dutrieux, P., and J. Kingslake (2021). Ice-shelf basal melt channels stabilized by secondary flow. Geophysical Research Letters, 48:1-11. doi:10.1029/2021GL094872.
- MacAyeal, D.R., Sergienko, O.V., Banwell, A.F., Macdonald, G.J., Willis, I.C., and L.A. Stevens (2021). Treatment of ice-shelf evolution combining flow and flexure. Journal of Glaciology, 67(265):885-902. doi:10.1017/jog.2021.39.
- Banwell, A.F., Datta, R.T., Dell, R.L., Moussavi, M., Brucker, L., Picard, G., Shuman, C.A., and L.A. Stevens (2021). The 32-year record-high surface melt in 2019/2020 on north George VI Ice Shelf, Antarctic Peninsula. The Cryosphere, 15:909–925. doi:10.5194/tc-15-909-2021.
- Keisling, B.A., Bryant, R., Golden, N., Stevens, L.A., and E. Alexander (2020). Does our Vision of Diversity Reduce Harm and Promote Justice? Geological Society of America (GSA) Today. 30. doi:10.1130/GSATG429GW.1.
- Wagner, T. J. W., Straneo, F., Rickards, C. G., Slater, D., Stevens, L. A., Das, S. B., Singh, H. (2019). Large spatial variations in the ﬂux balance along the front of a Greenland tidewater glacier. The Cryosphere, 13:911–925. doi:10.5194/tc-13-911-2019.
- Chaput, J., Aster, R.C., McGrath, D., Baker, M.G., Anthony, R.E., Gerstoft, P., Bromirski, P., Nyblade, A., Stephen, R.A., Wiens, D., Das, S.B., and Stevens, L.A. (2018). Near-surface environmentally forced changes in the Ross Ice Shelf observed with ambient seismic noise. Geophysical Research Letters, 45:181–187. doi:10.1029/2018GL079665.
- Carmichael, J.D., Joughin, I., Behn, M.D., Das, S.B., King, M.A., Stevens, L.A., and D. Lizarralde (2015). Seismicity on the Western Greenland Ice Sheet: Surface Fracture in the Vicinity of Active Moulins. Journal of Geophysical Research: Earth Surface, 120:1082–1106. doi:10.1002/2014JF003398.