About this Research Topic
The polar regions have experienced substantial change over the last two decades. Surface temperature increases in the Arctic are more than double the global average commensurate with increases in anthropogenic greenhouse gas emissions. Impacts of this warming include reduced sea ice and snow cover, increased atmospheric water vapor, and enhanced pole-ward transport of heat via the ocean. The southern polar regions have experienced less uniform warming with the largest increases over West Antarctica and the Antarctic Peninsula. Over the last 50 years, both the Antarctic and Greenland Ice Sheets have demonstrated accelerated solid mass discharge and runoff resulting in increased contributions to sea-level rise. Changes in these ice sheet systems are influenced by several factors that have caused the loss of ice shelves/ tongues, enhanced calving at marine-terminating outlet glaciers, increased surface melting, and changes in the modes and seasonal timing of hydrologic processes. A critical component of these ice sheet systems are shear margins, which regulate mass flux. An understanding of these changes are paramount to improving prognostic assessments of ice sheet mass loss. This proposed Research Topic seeks to highlight advances in our understanding of how both Antarctic marine-terminating and ice stream systems as well as Greenland’s outlet glaciers have responded to contemporary polar warming.
Outlet glaciers, ice streams and shelves are vital arteries for transporting ice from the interior of large ice masses to the ocean, contributing to sea-level rise. The long-term behavior of these systems are modulated by several complex interacting factors that are not well understood. This results in large uncertainty in the estimates of sea level rise because models lack the necessary physics to account for rapid changes, feedbacks and scaling effects that can augment the force-balance responsible for changes in mass flux. Many of these systems are defined by the presence of shear margins, which can either be topographically or bed controlled. We have seen dramatic changes in outlet glaciers and ice streams over Greenland and Antarctica. Changes in these ice masses have been driven by infiltration of copious surface melt water which can reduce the magnitude of resistance to flow, enhance acceleration-induced strain heating, and lead to damage, thereby altering ice rheology.
Recent works are exploring this problem-space, producing exciting new theories to explain observations and establish a foundation for prognostic assessment of ice sheet response to global warming. This Research Topic seeks to highlight research on shear margin observations and processes across the Greenland and Antarctic ice sheets forced by multi-scale variability in oceanic and atmospheric processes consistent with observed changes in polar climate.
This Research Topic solicits papers with topical focus on the changes in marine-terminating outlet glaciers, ice streams, ice shelves, and suture zones across Antarctica and Greenland. We solicit work examining the themes described above covering a range of methods, and a broad spectrum of spatial and temporal scales. This includes remote sensing, field observations, as well as theoretical, process, and modeling studies.
Keywords: Shear Margins, Ice Dynamics, Glaciology, Hydrology, Process
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