1
Introduction

1.1 Research Context and Academic Background

Glaciers and permafrost constitute two of the most important elements of the global cryosphere, a dynamic component of the Earth system dominated by cold climatic conditions and water in its solid form. Modern-day glaciers and ice sheets alone are estimated to cover a total area of over 16?million?km2 with the majority occurring in the form of the Antarctic and Greenland Ice Sheets (covering c. 14?million and 1.7?million?km2, respectively; NSIDC, 2019), with the remaining ice being distributed between 198,000 smaller glaciers and ice caps (Pfeffer et al., 2014). Meanwhile, permafrost regions are estimated to occupy an additional area of almost 23?million?km2 in the Northern Hemisphere alone, which equates to almost 24% of the Earth's exposed land area (Zhang et al., 2003). In combination therefore, the global cryosphere can be estimated to currently cover a total area of almost 40?million?km2, occurring primarily within the polar regions and high-altitude continental interiors.

In spite of their obvious geographical associations within similar climatic settings, surprisingly little research activity has focused on an examination of the nature and potential significance of the interactions between glaciers and permafrost. Part of the reason for this limited interest in glacier-permafrost interactions within the glaciological research community in particular relates to two widely held assumptions. First, that glaciers and permafrost are largely mutually exclusive with substantial thicknesses of glacier ice insulating any underlying permafrost from the prevailing climatic conditions and the heat generated by basal processes rapidly degrading any permafrost present. Second, where glaciers are observed to rest on permafrost, the resulting cold-based thermal regime is thought to preclude the operation of processes such as basal sliding and subglacial-sediment deformation that are in turn associated with dynamic ice flow and significant landscape modification. In addition to explaining the lack of targeted research activity, both assumptions emphasise the central importance of basal thermal regimes to any consideration of the connections between glaciers and permafrost (Section 3.2).

Cold-based glaciers occurring in areas of permafrost are therefore commonly conceptualised as being frozen to rigid and undeformable beds and to be both slow moving and geomorphologically impotent. They have consequently been disregarded as being of limited intrinsic research interest. In combination with their tendency to occur within remote regions that are typically difficult and costly to access, this has resulted in glacier scientists historically tending to focus primarily on temperate or warm-based glaciers, inducing a research bias that has resulted in our understanding of the behaviour of cold-based glaciers remaining limited in comparison. The same situation also applies to ancient glacial environments where glacial geomorphologists and geologists have tended to study areas glaciated by warm-based ice or characterised by hard bedrock, for example the Fennoscandian and Canadian Shields. In contrast, only a handful of studies have been published in international research journals that consider the potential interactions between cold-based ice sheets and the permafrozen sediments that underlie huge swathes of western Siberia and Arctic Canada and where permafrost is believed to have persisted throughout entire glacial cycles (e.g. Astakhov et al., 1996, section 5.4.3).

Some have argued that the limited interest in glacier-permafrost interactions is a reflection of a more fundamental and deep-seated dichotomy that has developed and persisted within the cryospheric sciences. Harris & Murton (2005) note that whilst the term 'geocryology' had originally been introduced to encompass both glaciers and permafrost, the introduction of the term 'periglacial' by Lozinski in the early 20th century resulted in a split between those interested in the study of glaciers and those interested in the study of frozen ground. These two communities have subsequently worked largely if not entirely in isolation, such that studies into the processes and products that occur at the interface between glaciers and permafrost have rarely received the focused and systematic research attention they deserve. They have instead been largely limited to isolated studies that have for example considered the potential role played by permafrost in promoting the development of large push moraines (e.g. Rutten, 1960; section 5.3.2). This enduring schism between the two disciplines is further illustrated by the usage of the term glaciology. Whilst this literally means the study of ice, it is widely regarded as referring more exclusively to the study of glaciers whilst the study of glaciers and ice sheets has been seen to be beyond the remit of permafrost scientists.

As a rare example of someone who has worked extensively across this research divide, Haeberli (2005) has argued that this schism has been to the detriment of both disciplines, resulting in terminological confusion and a hampering of research progress in both fields that have ultimately limited the credibility of cryospheric research as a whole. The lack of collaborative research appears particularly perverse when one considers shared research interests in the behaviour of ice-sediment mixtures for example (e.g. Waller et al., 2009a). Glacier scientists recognise the potential influence of the debris-rich ice that commonly occurs at the base of glaciers and ice sheets on their dynamic behaviour, sediment transport and geomorphic impact. At the same time, permafrost researchers have made significant progress in describing the nature, origin and engineering properties of different types of ground ice commonly found within permafrost regions. However, in spite of these overlapping areas of mutual interest relating to the study of essentially identical materials using similar techniques, the amount of collaborative research has remained limited until relatively recently (Section 2.5.1).

The resolution of a series of major research challenges relating for example to hazard mitigation in cold-climate regions, the secure burial of radioactive waste in cold regions and the potential impacts of future climate change on the global cryosphere have led to the recognition of a pressing need for a more integrated approach to the study of the cryosphere and renewed calls for the two research communities to collaborate more actively. This provides the opportunity to open up a 'new scientific land' (Haeberli, 2005, p36) in which workers in both communities can recognise and actively incorporate rather than ignore and exclude the findings of the other discipline. Such collaborative approaches are essential for the resolution of a range of interdisciplinary research questions that span the two subject areas. These include the accurate interpretation of buried ice within permafrost environments hypothesised to constitute buried glacier ice that has been preserved within the permafrost since deglaciation (Section 5.3.4). Similarly, recent work exploring the link between the dynamic behaviour of ice streams, basal freezing and till rheology has benefitted from the application of pre-existing models of frost heave originally devised by permafrost engineers (Section 4.3.3). These two brief examples provide an insight into the potential benefits that could be enabled by a more integrated approach. Most importantly, the fostering of a more interdisciplinary approach can prevent the promulgation of misconceptions and theoretical shortcomings that could have devastating implications in the context of natural hazards in high mountain areas (Section 5.6.1).

Whilst there are signs of a growing awareness of the importance of glacier-permafrost interactions, coupled with attempts to bridge the existing gap between glacier science and permafrost research, the fact remains that 'the geological and geomorphological processes at the interface between glaciers and permafrost have received less attention than they warrant, and the influence of the one on the other has been largely neglected' (Haeberli, cited by Harris & Murton, 2005, p2). It is hoped that this book will go some way to appreciating, emphasising and promoting the importance of glacier-permafrost interactions through a consideration of the historical roots of these interactions and its attempts to review recent developments, the state of current knowledge, the key gaps in our understanding and profitable avenues for future research.

1.2 Overview of the Significance of Glacier-Permafrost Interactions

As mentioned in the previous section, one of the principal reasons behind a lack of research interest in glacier-permafrost interactions has stemmed from the assumption that glacier-permafrost interactions are of limited extent and that glaciers resting on permafrost are slow moving and geomorphologically ineffectual. Research over the past 30?years in particular has however demonstrated that these assumptions are by no means universally applicable. The rebuttal of these assumptions has in turn stimulated renewed interest in the nature and significance of glacier-permafrost interactions that are...