Research
What processes govern the rate of ice flow? How will ice sheets accelerate in the future?
The flow of ice from grounded regions to the ocean is a major control on the rate of ice loss from ice sheets. The flow and deformation of ice is complex, affected by the microstructure and material properties of the ice itself, and the environment the ice is flowing in. However, these processes are currently not well understood or incorporated into ice sheet models. In our group, we apply theories of the deformation of polycrystalline materials developed in materials science, metallurgy, and rock mechanics to ice sheets in order to develop a comprehensive theory of ice flow and models for the effects of physical processes on ice viscosity.
Selected Publications & Projects:
Publication: Ranganathan, M. & Minchew, B. A modified viscous flow law for natural glacier ice: Scaling from laboratories to ice sheets, Proceedings of the National Academy of Sciences, 121(23), doi:10.1073/pnas.2309788121
Publication: Ranganathan, M., Minchew, B., Meyer, C., & Pec, M., (2021). Recrystallization of ice enhances the creep and vulnerability to fracture of ice shelves, Earth and Planetary Science Letters, 576:117219. doi:10.1016/j.epsl.2021.117219.
How does ice fracture, and how does damage in ice sheets affect the rate of ice flow?
Ice is a unique material that both flows and fractures at natural conditions (stresses and temperatures), which provides an added challenge for modeling ice sheet dynamics: we have to understand when ice flows and when it fractures, and we have to be able to model both processes simultaneously. In our group, we apply continuum damage mechanics concepts to ice sheets to understand (1) under what conditions ice fractures instead of flows, (2) what physical processes sets this boundary between brittle and ductile behavior, (3) how ice flow and ice fracture influence each other.
Selected Publications and Projects:
Publication: Ranganathan, M., Minchew, B., Meyer, C., & Pec, M., (2021). Recrystallization of ice enhances the creep and vulnerability to fracture of ice shelves, Earth and Planetary Science Letters, 576:117219. doi:10.1016/j.epsl.2021.117219.
Project: Ranganathan, M., Robel, A., Assessing the role of feedbacks between ice flow and fracture in future Antarctic mass loss and global sea-level rise, NOAA Climate & Global Change Postdoctoral Fellowship, 2022-2024
How do we quantify and constrain uncertainty in ice sheet models?
Uncertainty is a key element in our ability, as a society, to understand the future effects of ice sheet change. A necessary part of adaptation efforts to sea-level change is knowing how much sea levels might change, and how certain those projections are. In our group, we apply applied mathematics methods for data assimilation and uncertainty quantification to (1) improve our understanding of the underlying uncertainties in ice sheet projections, and (2) constrain those uncertainties using observations.
Selected Publications and Projects:
Publication: Ranganathan, M., Minchew, B., Gudmundsson, G.H., & Meyer, C., (2021) A new approach to inferring basal drag and ice rheology in ice streams, with applications to West Antarctic Ice Streams. Journal of Glaciology, 67(262), 229-242. doi:10.1017/jog.2020.95
Justice, decolonization, diversity, equity, and inclusion in the geosciences
The geosciences are an important force for good as our climate changes, but currently are also one of the least diverse STEM disciplines. From a research perspective, we seek to (1) quantify the loss of diversity along the academic track and identify the transitions at which attrition is high, and (2) identify structural and institutional factors causing this attrition. From an educational perspective, we seek to introduce conversations around the geosciences and colonialism into geoscience curricula. From a group perspective, we are committed to improving diversity through recruitment and training of students, equitable and inclusive mentoring, and building a positive group culture. Please feel free to reach out to Dr. Ranganathan to learn more about this commitment.
Selected Publications and Projects:
Publication: Ranganathan, M., Lalk, E., Freese, E.M., Freilich, M.A., Wilcots, J., Duffy, M.L., Shivamoggi, R., (2021). Trends in the representation of women amongst geoscience faculty from 1999-2020: the long road towards gender parity, AGU Advances, 2(3). doi:10.1029/2021AV000436
Course: Racism, Colonialism, and Extraction in the Geosciences, co-developed by M. Ranganathan, J. Wilcots, M. Freilich, L. Freese, M. Fendrock for MIT EAPS, syllabus available here.