Prof. em. Kolumban (Koli) Hutter passed away on December 20, 2024, at the age of 83 at his home in Zurich, surrounded by his family. Koli leaves behind his widow Barbara, and their daughters, Bettina and Katja, together with their families.
Koli was one of the most outstanding glaciologists of his time, often recognized as one of the Fathers of Theoretical Glaciology, together with his colleagues Andrew Fowler (Oxford) and Leslie Morland (Norwich). Koli came to glaciology from theoretical and applied mechanics, a career move he used to mention as “I was only asked to help out a little in glaciology” in his typical understating fashion. In the late 1970s and early 1980s, Koli developed a ground-breaking framework for the theoretical analysis of ice sheet dynamics: he approached the complex problem of ice sheet flow with methods from the perturbation theory, known from classical fluid dynamics, and introduced the Shallow Ice Approximation (SIA) framework to glaciology. The SIA enabled the first modern numerical simulations of continental-scale dynamics of ice sheet flow, including quantification of ice mass loss contributing to global sea level rise. It was later described in detail in Koli´s book “Theoretical Glaciology” (1983) [1], nicknamed “the bible”, as it became a glaciological milestone by setting new standards of mathematical rigor and formally introducing the name of this field into glaciology, as we know it today. These achievements placed Koli in the line of giants on whose shoulders would stand the next generation of numerical glaciologists and modelers, and scientists serving on expert assessment panels, such as the Intergovernmental Panel for Climate Change (IPCC).
Today, more than 40 years after the introduction of the SIA, and in a totally different world with regards to computing infrastructure, much more complex ice sheet models are used on an everyday basis across the scientific community. This does not mean, however, that SIA models have lost their relevance: they remain invaluable in many situations, and for many students they continue to be the first ice sheet models they learn. The importance of Koli’s contribution to glaciology was already expressed in the late 1980s by Garry Clarke (Vancouver), who acknowledged that it was work like Koli’s revolutionary thinking (rather than technological advances) that spurred progress in glaciology at a time when routine glaciological measurements differed only in speed and accuracy with which they could be taken decades ago. Apart from the SIA, notable work ahead of its time included Koli’s theoretical contributions to crystallography of ice, which inform strength and other mechanical properties of cryospheric bodies at microscale and macroscale. In recognition of his outstanding contributions to glaciology, the International Glaciological Society (IGS) awarded its Seligman Crystal to Koli in 2003. Koli was also dedicated to providing what today is referred to as “service to the community”: He was Chief Editor for four volumes of the Annals of Glaciology over a period of 10 years, Scientific Editor of numerous Annals of Glaciology, IGS Vice President for two terms, a member of the IGS Council during 1996–2000, and a member of both the Publications Committee and the Awards Committee at various times.
Koli’s work was by no means restricted to glaciology, however. It extended into the fields of continuum mechanics and rational thermodynamics, physical limnology, mechanics and dynamics of geophysical porous and granular materials, among others. Together with Ingo Müller (Berlin) he founded the journal “Continuum Mechanics and Thermodynamics” in 1989, which rose to become one of the most authoritative journals on the field under his co-lead as Chief Editor until 2005. His pioneering work in granular flow dynamics in 1989, known as the Savage–Hutter model, became a landmark in the field and continues to be widely utilized as a foundation in various advanced granular dynamic models. Koli’s work was also leading in physical limnology. He, together with his PhD students and colleagues, investigated the dynamic behaviour of more than ten of the most important lakes in Europe and the world, including their surface, internal and topographic waves and wind-induced movements. Over his career, he published nearly 500 journal articles and book contributions, as well as more than 20 books. Even after his retirement, Koli, together with his collaborators, published two more book series, “Physics of Lakes” and “Fluid and Thermodynamics”, three volumes each. In recognition of the importance of his work, Koli was also awarded the Max-Planck Research Prize in 1994 and the Alexander von Humboldt Prize in 1998.
Koli’s journal and book publications are too numerous to list, and even to pick highlights is difficult because there are so many of them. A selection made by Koli himself can be found in his speech when receiving the Seligman Crystal in 2003 [2], while an older selection is contained in Garry Clarke’s 1987 “short history” paper [3]. It is a really rewarding undertaking, especially from a 2025 perspective, to read the transcript of an almost three hour long interview that William Thomas, Niels Bohr Library and Archives, American Institute of Physics, conducted with Koli in Zurich in 2012 [4]: In this interview, Koli was ahead of his time by not only focusing on work achievements, but also addressing the many challenges that an academic career can imply, and how he felt about it – reflections that now start to take regular place in academic work life discussion inspired by the Equity, Diversity and Inclusion (EDI) framework.
Bearing a tall and puissant figure, penetrating gaze, and strong personality, Koli would make his presence noticed wherever he entered. All his endeavours were performed with unflagging vigour, whether he was giving a lecture, writing a book, travelling to and fro between Zurich and Darmstadt, or simply walking to work. Keeping up with his pace was no task for the rambler. His daily schedule was so demanding that it required great discipline and hard work starting already in the wee hours of the morning. His office was his temple, furnished with a beautifully carved wooden desk, backed by an impressive scientific library and facing a larger-than-life bust of one of his greatest icons, Albert Einstein. Whoever visited Koli’s villa in Zurich would listen to him proudly telling that Einstein lived just 300 m from his home. At conferences and meetings, it could hardly be missed that Koli’s knowledge spanned more disciplines than one can easily list. From project evaluation meetings of the German Science Foundation (Deutsche Forschungsgemeinschaft) it is remembered that more often than not Koli would know more about many a proposer’s project than the proposer themselves. With his knowledge, Koli initiated well-meaning, in-depth and challenging, enriching, and enjoyable discussions among peers, always aimed at advancing science.
Koli’s reviews, whether of student reports or manuscripts submitted to prestigious peer-reviewed scientific journals, were always utterly rigorous – and always utterly factual and fair. To our knowledge, he never hid behind anonymity. When his postdoctoral researchers were tasked to act as reviewers, Koli would stick his head into their offices with the reminder that whatever critique there was to be made, words should be chosen with great care, and arguments were to be formulated such that one felt comfortable signing with one’s name, rather than anonymous. And indeed, for many of us that had the privilege of being reminded of this by Koli, “anonymous” has since never been an option when acting as reviewers.
Apart from setting the highest standards in reviewing and editing, the above is also but one example of Koli’s unwavering efforts to teach the next generation of scientists. Despite his many accolades, Koli indeed always regarded his students as his real treasure. During his whole career, he would make no distinction about age, gender, race, nationality, culture or religion. He regarded all of his students as equally worthy. As their supervisor, Koli was very demanding, but also extremely generous. Whenever the situation required it, he would offer his help and support to a student in need, even offering his own place as shelter, and he would spare no means to defend his students in conflicting situations.
Koli would even stand up for other colleague’s students, in the most amazing ways. One telling example is from an occasion when Koli was asked to be an external, and the only international, examiner at a PhD defence. Prior to the defence, the PhD candidate had been very fortunate to already have been offered a good position at another university, to continue on the academic career track. However, the starting date for this position was rather soon, which left little time for the candidate to finish the last details of the thesis prior to the defence. At the actual defence, Koli was very forward in expressing his concern about certain aspects of the PhD thesis and requested these to be corrected before the thesis would pass. The candidate was very upset but Koli was adamant. After the defence, the other national examination committee members were chastising Koli for being so tough on the candidate. His reply was re-iterative, that there had been mistakes in the dissertation that had to be corrected. It is quite likely that his sternness was interpreted as arrogance, but nothing could be further from the truth: After the examination committee had parted, Koli contacted his secretary, informing her that he would not be back at university for at least a week, and then extended his hotel stay in the city where the PhD defence had taken place. All costs associated with the extended stay, hotel and rescheduled flights, were paid by Koli out of his own pocket. Koli then spent the whole week working with the PhD candidate — going through the dissertation in detail and explaining what needed to be corrected, and providing guidelines on how it should be corrected. After this very long and intense week, the PhD candidate was not only able to hand in a thesis that was approved, but also to show up at his new place of work in time to take up his employment.
Perhaps never thinking that it would be used to describe him at some point, Koli would often say that the success of a scientist should be measured neither by his accolades, nor by the number of publications he amasses, but rather by the success of his students. Reckoning the impressive number of leading scientists spread over the world, who happen to be Koli’s alumni, we can state with conviction that Koli was indeed an exceptionally successful scientist.
As a passionate researcher, supervisor, teacher and editor throughout his active work life, few glaciologists may not have come into contact with Koli in one way or the other. We remember him as a colleague whom one with great certainty could meet in his university office before 6 a.m., drinking tea from a thermos bottle and inviting one to step in, but only interrupting his intense production of handwritten notes on backsides of misprinted pages fetched from the printer when the topic offered for the morning discussion was deemed sufficiently interesting. But most of all, we remember Koli as a true friend, and we are infinitely grateful for the time we were given to spend with him.
Nina Kirchner, Sérgio Henrique Faria, Ralf Greve, Willi Hager, Ute Herzfeld, Magnús Már Magnússon, Leslie Morland, Yongqi Wang
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[1] Hutter, K. (1983) Theoretical Glaciology. Dordrecht: Springer, doi: 10.1007/978-94-015-1167-4
[2] https://www.igsoc.org/wp-content/uploads/2022/03/ice_135_2004.pdf
[3] Clarke, G.K.C., 1987. A short history of scientific investigations on glaciers. Journal of Glaciology 33 (S1), 4-24, doi:10.3189/S0022143000215785
[4] https://www.aip.org/history-programs/niels-bohr-library/oral-histories/40452