Glacier moss balls exhibit mysterious herd-like motion

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Glacier moss balls are globular, ~10 cm masses of moss, with small amounts of sediment found on some glaciers. These enigmatic, rare components of glacier biology have seen some study at select glaciers around the world, but their longevity on glaciers and patterns of motion have been entirely unknown until now.

Glacier moss balls on the Root Glacier, Alaska

Starting in 2009, before I’d begun my Ph.D. program, now-UIdaho professor of wildlife biology, Sophie Gilbert, and I studied an unusually dense concentration of glacier moss balls on the Root Glacier, in Wrangell-St. Elias National Park and Preserve, Alaska. We tagged individual glacier moss balls with unique colored glass beads to identify them, then revisited the colony every 5-7 days to study their motion. We also returned in subsequent years to re-identify individuals. Dr. Gilbert and I later teamed up with Dr. Scott Hotaling to publish this work.

We found that moss balls exhibited consistent, herd-like motion, changing both their speeds and travel directions together. Moss balls moved on average 2.5 cm per day, at rates somewhat controlled by the amount of glacier surface ablation. Early during our 1.5 month study period in 2009, moss balls rolled predominantly towards the south, but later moved towards the west. We weren’t able to explain this migratory, herd-like motion by considering the downhill, wind, or solar radiation directions. Thus, the changing directions of their motion remains a mystery. By revisiting our site in the three subsequent years, we were able to find that moss ball growth is relatively slow and that individual moss balls can persist on the glacier for many years- at least six but potentially much longer.

This work was published in May 2020 in the journal Polar Biology. A twitter thread about this work, with more photos, is here.

The moss ball colony we studied, where moss balls rolled around in herd-like fashion over the dirty ice surface.
Cross section of a typical Root Glacier moss ball

Chris Miele defends dissertation proposal, advances to Ph.D. candidate

posted in: Research, Teaching | 0

Ph.D. student Chris Miele, in the UI Glacier Dynamics lab, successfully defended his dissertation proposal today. His dissertation, titled “Transition zones in floating glacier ice in Greenland,” is focused around better understanding the dynamics and iceberg calving of marine terminating glaciers. To an audience of over 35 Zoom attendees, Chris did a great job presenting his work with both physical rigor and engaging humor. Chris subsequently passed his comprehensive exam, and advanced to Ph.D. candidacy.

Great work, Chris! Congratulations!

Thanks are also due to Chris’ advisory committee members, Dr. Ellyn Enderlin, Dr. Eric Mittelstaedt, and Dr. Gabriel Potirniche.

UI grad students present at Northwest Glaciologists meeting

posted in: Greenland, Research | 0

Three UI students, Chris Miele, Emma Swaninger, and Abby Lute, attended the 2019 Northwest Glaciologists meeting in Corvallis, Oregon, last week. Chris and Emma are students in the Glacier Dynamics lab and shared their work focused on understanding dynamic changes around iceberg calving, whereas Abby is a collaborating student in the lab, advised by John Abatzoglou in the Geography Department. Chris, Emma, and Abby did great jobs communicating their work and fielded questions from an engaged audience. As a whole, the lab had a great time sharing science and connecting with friends old and new.

In the attached pictures, Chris and Emma present their research.

Lab group prepares for Northwest Glaciologists’ meeting

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Members of the Glacier Dynamics lab at UIdaho are preparing this week for next week’s gathering of Northwest Glaciologists. Chris Miele will present a theory-based analysis on the interplay between submarine melt and iceberg calving, and how calving varies with the spatial pattern of submarine melt. Emma Swaninger will present on the response of Rink Glacier to the brief formation of ice melange within its West Greenland fjord. And Abby Lute, a Ph.D. student on whose committee Tim serves, will present her work on the climatic and other environmental factors controlling the distribution of rock glaciers.

It’s an exciting time as we hustle to prepare results, and we’re looking forward to meeting next week with friends and colleagues in Corvallis, Oregon.

Conference symposium highlights latest in Glacier Seismology

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At the International Union of Geodesy and Geophysics meeting in Montreal, Canada, Bartholomaus co-convened and presented during a symposium on Glacier Seismology. The well-attended symposium featured talks from authors around the world on topics as diverse as ice shelves, basal sliding, and avalanches. Bartholomaus presented his most recent work on the use of seismology to reveal the workings of the subglacial hydrologic system of Lemon Creek Glacier, Alaska.

Bartholomaus-mentored Ph.D. student wins Early Career Award for outstanding paper

Denis Felikson has been awarded the 2019 Early Career Award by the International Association of Cryospheric Sciences. Tim Bartholomaus had the privilege of working with Denis while the two of them were at the University of Texas in Austin, and worked with Ginny Catania. During that time, Denis published a paper with Bartholomaus that demonstrated how glacier geometry in Greenland controls the spatial pattern of ice loss from the ice sheet. Denis is now a postdoc at the NASA Goddard Space Flight Center. Congratulations, Denis! The citation is found here.

Tristan Amaral defends M.S. thesis

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UI Glacier Dynamics lab member Tristan Amaral recently gave an excellent summary of his master’s thesis research, “Validation of iceberg calving models on Greenland outlet glaciers.” During his presentation, Tristan discussed the challenges of identifying a universal calving law, appropriate for the diversity of tidewater glaciers in Greenland, his strategy for assessing these calving laws, and the relative accuracy and reliability of different calving laws.

Following his graduation, Tristan is working on completing the final revisions to his paper, to be submitted for peer review this summer at the Journal of Geophysical Research. In a month, he’ll be headed up to Alaska to work at Denali National Park for the summer, as an intern through the GSA Geoscientists in the Parks program.

Ph.D. opportunity in Greenland tidewater glacier dynamics

The Glaciers Dynamics lab at the University of Idaho seeks a curious, hard-working, quantitatively-oriented Ph.D. student to study tidewater glacier dynamics around the Greenland Ice Sheet.  Following Saturday’s successful launch of ICESat-2, the successful applicant will draw on the satellite’s high spatial- and temporal-resolution elevation data to understand outlet glacier change.  Potential research targets include iceberg calving, ice-ocean interactions, crevassing, and glacier bed coupling.  The successful applicant will contribute to a NASA-funded project, co-led with Dr. Ginny Catania of the University of Texas, and will begin with at least three years of salary and tuition support as a research assistant.

Highly motivated candidates with backgrounds in geophysics, earth science, physics, mathematics, engineering, or other quantitative fields are encouraged to apply.  Programming experience with Python, R, Matlab, or similar is regarded well.  Our group values the diverse backgrounds of our members, and individuals identifying with groups underrepresented in the Earth Sciences are especially encouraged to apply.  Student support is available starting January 1, 2019, for which applicants are encouraged to apply by October 1, 2018.  However, start dates later in 2019 are possible, with later application deadlines.

The University of Idaho, in Moscow, ID, is located in the northern panhandle of Idaho, in the picturesque, vibrant, walkable, small town of Moscow (population of 25,000;  UI has an enrollment of 12,000 students and is the state’s flagship research university.  Moscow features access to the mountains and rivers of the northern Rockies and a low cost of living.  Additional information about our group can be found at  Information about the Department of Geological Sciences at the University of Idaho, including how to apply, is here:  To learn more, please send a CV and short expression of interest to

And finally, congratulations to the NASA ICESat-2 team on their successful launch over the weekend!  (

Image credit: NASA


Student researchers advance understanding of iceberg calving

posted in: Greenland, Research | 0

Thanks to the hardworking team of student researchers who worked together over the summer on our NASA-funded project to understand iceberg calving around the Greenland Ice Sheet.  Undergraduate researchers Danny Bugingo and Rian Brumfield worked with M.S. candidate Tristan Amaral to compile and process the remote sensing imagery necessary to test and validate “calving laws.”  These calving laws represent the numerical rules applied in ice sheet models to define the terminus boundary of glaciers that flow directly into the ocean.  As such, evaluating their performance and selecting the best calving laws for inclusion in ice sheet models is a critical component of accurate forecasts of future ice sheet change.  This project represents the focus of Tristan’s M.S. research.