Antartic Ice Dynamics

Oliver Marsh presented his research on Antarctic ice dynamics and climate change, discussing the rapid changes occurring in the ice sheet system and the importance of understanding tipping points to predict future behavior. He explained various monitoring techniques and research projects being conducted at the British Antarctic Survey's research stations, including studies on ice shelf properties, fracture behavior, and iceberg tracking. The discussion covered climate modeling challenges, the impact of climate change on sea levels, and the limitations of various geoengineering solutions, with particular emphasis on the role of ice shelves in Antarctica's dynamic environment.

Oliver Marsh, a glaciologist at the British Antarctic Survey, presented on his research focusing on iceberg formation, ice shelf dynamics, and the use of new monitoring technologies in Antarctica. He discussed the rapid changes occurring in the climate system, as highlighted by the Intergovernmental Panel on Climate Change, and emphasized the acceleration of ice sheet and glacier contributions to sea level rise. Oliver explained the concept of tipping points in the Antarctic ice sheet system and the need to understand these thresholds to predict future changes.

Oliver discussed the stability of Antarctic ice configurations, noting that past glacial maximums and warm periods have shown different ice sheet states, with some configurations involving significant ice loss that could lead to 6 meters of sea level rise. He explained the marine ice sheet instability process, where warm water melts ice shelves, causing a positive feedback loop of ice loss in areas with a seabed below sea level, particularly in West Antarctica. Oliver highlighted the importance of ice shelves, which are sensitive to climate change and act as a cork holding back inland ice, and mentioned recent observations of substantial melting and thinning of ice shelves, some losing up to 20% of their thickness in the last two decades. He also described Hallie, a British Antarctic Survey research station on the Brunt Ice Shelf, as an ideal location to study ice shelf processes due to its unique setting.

Oliver explained the process of raising the Halley research station in Antarctica to avoid being buried by snow, which involves hydraulics and takes about two days each season. He described the station's various scientific activities, including atmospheric monitoring, space weather research, and glaciological studies. Oliver also discussed the station's recent relocation due to cracks forming in the ice shelf, which led to a change in its operational system. He explained how they monitor the ice shelf's movement and strain rates using GPS-like instruments and satellite data, which helps predict potential threats to the station.

Oliver discussed the use of various instruments to study ice shelf behavior, focusing on a phase-sensitive radar system that measures crack width and a GPS system to track iceberg drift. He explained how tides influence ice shelf dynamics, with a recent carving event of 1,500 square kilometers occurring during spring tides. Oliver also described other monitoring techniques, including ground-based radar systems and satellite data, emphasizing the importance of ground validation for satellite measurements.

Oliver presented on his research studying ice shelf properties and fracture behavior in Antarctica. He explained their drilling project 40 miles from Halley Station, which involves collecting ice samples to study physical properties like grain size and crystal structure, rather than focusing on chemical analysis. Oliver described their development of a phase field model to simulate ice fracture over decades to centuries, which they are now applying to predict future behavior of the ice shelf. He noted that the Stank and Wales ice tongue has reached its largest extent in observed history, suggesting an overdue major calving event could occur soon, though he hesitated to make specific predictions without running the model for the area.

Oliver explained the trajectory of icebergs, noting that southern hemisphere icebergs travel in a predictable anti-clockwise route but often get grounded or break up in the Southern Ocean. He clarified that while ice shelf calving does not contribute to sea level rise, other factors like thermal expansion and melting of land-based ice are significant contributors. Dick inquired about measuring ice shelf formation rates, and Oliver described how satellite data is used to track ice movement and replenishment despite challenges in the grounding zone region.

Oliver discussed the challenges of assessing climate tipping points, explaining that while thresholds can sometimes be modeled, measuring when they are crossed remains difficult, particularly for ice sheet instabilities. He described his research on developing a physics-based model to predict ice sheet behavior without relying on observed data, which could help predict future changes in Antarctica. The discussion concluded with practical details about fieldwork in Antarctica, including the logistics of setting up instruments across cracks and the challenges of acclimatizing to extreme temperatures.

Oliver explained that past CO₂ levels were higher than today's, and his team is analyzing ice cores that could date back to an interglacial period. He discussed the impact of climate change on sea levels, noting that coastal cities and low-lying areas like Bangladesh could face displacement issues. Shelly raised questions about satellite measurements of sea level rise and a recent study on reduced cloud cover's correlation with temperature rise, which Oliver attributed to the IPCC report's comprehensive review process. Bob mentioned potential links between industrial pollution and reduced cloud formation, while Shelly and Bob debated the IPCC's modeling of clouds and its reliance on large grid systems.

Dick inquired about the research on water vapor's role in climate change, noting its abundance in the atmosphere compared to other greenhouse gases. Shelly and Oliver discussed water vapor's significant impact as a greenhouse gas and its interaction with other gases, while Carl explained its role as an amplifying factor rather than an originating one. Shelly mentioned a recent study challenging the accuracy of man-made CO₂ contributions, highlighting natural sources. Oliver addressed the feasibility of using icebergs as a water resource, noting economic challenges and seasonal variability in Antarctica's sea ice. A member suggested reviewing a previous talk on geodesy and space measurements for further insights, and Oliver clarified temperature profiles and melting processes in ice shelves.

Oliver discussed the challenges and limitations of geoengineering schemes to combat climate change, emphasizing the feasibility and cost issues. He highlighted the importance of his research station in Antarctica, which supports space weather forecasting and provides unique data on ice shelf monitoring. Oliver also explained the differences between ice dynamics in Antarctica and Greenland, noting that Antarctica has greater potential for rapid ice loss due to marine ice sheet instabilities. The discussion concluded with a brief mention of a historical method for transporting ice.