Glaciology is the study of glaciers, from small alpine valley glaciers with complex hydrology and influence over the local environment to large ice sheets with significant importance to global climate and sea-level. The majority of the world's glaciers are found in the polar regions and they have fundamental impacts on almost all areas of polar research. There are strong interdisciplinary links in particular with geology, hydrology, oceanography and atmospheric sciences.
There are a number of sub-disciplines or areas of research within Glaciology, often linking into other disciplines such as earth-sciences and physics. Here are a few; click on them to learn more about these exciting areas of study.
Glacial geomorphology involves the study of glacial landforms. It is important to understand how glaciers have behaved in the past in order to predict what will occur in the future. Glacial geomorphologists combine a knowledge of glacial processes with observation of landforms to infer glacier behaviour over the last decades to millions of years.
Remote sensing is an important technique for observing present day glacier change. Satellite remote sensing has developed rapidly over recent years with the launch of satellites such as ICESat and Cryosat designed specifically for monitoring polar ice. These satellites are complemented by airborne and ground-based remote sensing techniques. Changes in the mass of polar ice sheets can now be measured using satellites such as GRACE to record small variations in the earth's gravity; changes in ice volume are measured by high precisions altimeters and changes in the mass budget of the ice sheets are measured by feature tracking and interferometric synthetic aperture radar (InSAR).
Glacier modelling is used to predict the future of ice sheets and glaciers. Developing useful glacier models is vital in predicted the influence of changing climate on global sea-level and water resources. Ice sheet and glacier models vary in scale from high resolution simulations of iceberg calving and ice shelf fracture mechanisms to full approximations of ice sheet response to climate over thousands of years.
Ice Core Studies:
Permafrost is recognized by the World Climate Research Programme (WCRP/WMO) and Climate and Cryosphere (CliC) as a key element of the Earth System. Permafrost is present in ca. 25% of the Northern Hemisphere continental area and on all the ice-free areas of the Antarctic continent, including wide areas under the ice-sheet. Permafrost is central to the carbon cycle and hence to the climate system, especially due to methane and carbon dioxide release following permafrost degradation. This issue is especially sensitive in the Arctic, but detailed studies are lacking in the Antarctic. Therefore, especially in the ice-free areas, the warming of permafrost (climatic and human-induced) can generate problems to existing or planned research facilities, which can be potentially subject to risk. Permafrost monitoring is therefore also an important issue relating to environmental impact assessment and mitigation in ice-free terrain Antarctic facilities.
Sea ice is defined as ice that grows in the ocean. It is an integral component in an intricate ecosystem that provides stability and nourishment in the food web in the Arctic and Antarctic regions. Though this is a significant component in ecological, biogeochemical, and geophysical systems at the poles, it also influences oceanic and atmosphere interaction on a global level. The physical structure of sea ice provides a significant contribution to Earth's ability to reflect and absorb incoming solar radiation. The reflectivity studied is known as albedo, which is the ratio of outgoing reflected radiation from the surface to incoming radiation. Optical properties in the different sea ice types, such as brine inclusions, air, and solid salts, govern the portion of incoming radiation that is reflected,absorbed, and scattered. Another important aspect of sea ice thickness pertains to the sea ice brine flux and its effect on thermohaline circulation (THC) affecting deepwater formation and upper ocean stability through saltwater and freshwater fluxes.
Within the past few decades, global climate change has led to widespread changes in the mass and aerial extent of the Earth's glaciers, ice sheets, and sea ice as well as changes in the temperature and circulation of the oceans. This research feature focuses on the interactions between glaciers, ice sheets, sea ice and the oceans, the feedbacks inherent to the coupled systems, and the broader impacts of changes in ice-ocean interactions. The following two sections provide a brief overview of ice-ocean interactions at/near glacier margins and beneath sea ice.
Glacier ice-ocean interactions: Glaciers that terminate in the ocean (i.e., marine-terminating or tidewater glaciers) lose mass at their marine margins through iceberg calving, meltwater runoff and submarine melting. The stability of a glacier is dependent on a balance between mass entering and exiting a catchment. In contrast with land-terminating glaciers, marine-terminating glaciers are able to undergo rapid changes in mass because changes in ocean forcing can lead to rapid changes in the calving and/or submarine melt rates, which can influence glacier flow dynamics by controlling the location and shape of the glacier terminus (which can be grounded or floating). The location and shape of the terminus influences the balance of stresses controlling ice flow; thus, changes in ice-ocean interactions have the potential to strongly influence a glacier’s mass balance.
The magnitude and timing of iceberg calving can be quantified using remote sensing and in situ observations (e.g., satellite imagery, time lapse photography, scanning lidar, and seismic measurements), however the processes controlling calving are poorly understood. Observations and modeling suggest that calving is a two-stage process: (1) fracture/detachment and (2) seaward transport. Transport of the detached ice can be influenced by both the thickness of the glacier relative to the depth of the neighboring ocean and the rigidity of ice mélange (a mixture of sea ice and icebergs).
Due to the difficulty in predicting the magnitude and timing of calving events, the proglacial environment of a tidewater glacier is not easily accessible and direct measurements of submarine melting and subglacial runoff are difficult to collect. Numerical and physical models used to look at this relationship have found that the enhancement of submarine melting occurs when cold fresh buoyant meltwater from the subglacial system entrains warm saline ocean water as it moves up the glacier terminus towards the ocean surface. As such, the magnitude of submarine melting will vary with both the ocean water temperature and the strength of the rising subglacial meltwater plume. Estimated melt rates suggest that submarine melting can be on the order of meters per day for some glaciers but vary widely between glaciers. It has also been suggested that an increase in submarine melt rates in the 1990s and 2000s may have triggered the recent rapid changes in ice flow at numerous outlet glaciers draining the Greenland and West Antarctic ice sheets. However, the construction of submarine melt rate time series is hindered by the scarcity of in situ hydrographic observations and the limitations of remote sensing techniques, preventing a thorough analysis of temporal changes in submarine melting with respect to changes in glacier behavior.
Tidewater glacier stability and the impact of tidewater glaciers on their environment is complex due to the numerous feedbacks occurring in the glacier ice-ocean system. The impact of changes in the glacier-ocean system is not only limited to sea level rise, but also smaller scale changes such as local biologic communities that rely on calved icebergs for breeding or nutrient-rich meltwater plumes for food. Thus, it is imperative that research efforts continue to focus on developing a better understanding of glacier ice-ocean interactions.
Sea Ice-ocean interactions: Sea ice is a key indicator of the global climate change. Recent decades have been marked by rapid sea ice decline in the Arctic Ocean. In contrast, no significant decrease in Southern Ocean sea ice has been observed. Although the widespread changes in sea ice are concurrent with changing atmospheric and oceanographic conditions, sea ice-climate models are generally not capable of properly simulating the observed variability of Arctic and Antarctic sea ice cover. The failure of these models is likely due to the poor understanding of processes governing sea ice-ocean interactions. As such, a better understanding of sea ice-ocean interactions and an improved parameterization in climate and sea ice in Earth system models must be developed.
An important aspect of sea ice-ocean interactions that warrants further exploration and model development is the interaction of sea ice and the ocean with the atmospheric boundary layer. The formation and melting of sea ice in the polar regions are critical processes that must be included in Earth system models because the associated heat, moisture, momentum and gas exchanges at the ocean-sea ice-atmosphere interface are strongly influenced by changes in sea ice cover. Additionally, changes in sea ice cover influence the penetration of solar radiation and wind-induced turbulent mixing of the upper ocean layer, which will influence the biogeochemical cycling and ecosystem functioning in the upper ocean layer and lower atmosphere.
It is important to remember that the current state of knowledge regarding sea ice-ocean interactions was developed over the past several decades; a time period marked by a shift from relatively stable sea ice cover to the most recent period of declining sea ice extent and thickness. As such, the recent changes in sea ice extent, thickness, and distribution (particularly in the Arctic Ocean) have revealed knowledge gaps that must be addressed by the scientific community in a timely manner. For example, the recent transition from widespread multi-year sea ice towards predominantly first-year ice in the Arctic may enable the penetration of a more solar radiation beneath the ice than observed in the past. Consequently, the upper-ocean warming associated with increased penetration of solar radiation can contribute to enhanced melting of sea ice, further enhancing absorption of solar radiation by the upper ocean layer (i.e., positive feedback loop). Changes in sea ice cover and associated changes in the upper ocean temperature and salinity can lead to changes in sea ice algae/phytoplankton productivity, which will in turn influence the marine food web and carbon cycling. Interconnections such as these make the study of sea ice-ocean interactions an inherently multidisciplinary task.