Speaker Dr. Eugene Domack: Polar Perspective of Rapid Environmental Change and Relevance to Deep Time Records of Icehouse to Greenhouse Transitions

September 1, 2017
Monday, September 18, 2017 - 3:00pm
BPCRC Auditorium (240 Scott Hall)
Eugene Domack

Rates of environmental change in the polar cryosphere have been profound and relatively well recorded by satellite remote sensing and surface observations over the past four decades. Such changes include: rapid declines in sea ice, ice shelf extent, retreat of grounding line positions, and increase in ocean temperature; all of which pose questions of how such events are recorded in the existing seafloor sediment and biota. Answers to these questions are not only important to gauge the reach of change in the modern Earth system, but also how the stratigraphic and fossil record might have recorded similarly paced changes in the past, such as during transitions from so called “icehouse” to “greenhouse” states. For example, sedimentation rates, and patterns and biotic response within the Larsen Ice Shelf system of Antarctica are uniquely constrained in space and time due to foresight in international research efforts over the past decade or more. Following ice shelf collapse, sedimentation rates and organic matter flux across portions of the seafloor increase by four orders of magnitude or more. This dramatic purging of sediment sources (via ice rafting and hemi-pelagic sedimentation) is accompanied by significant changes in pelagic and benthic communities which include both diversity and abundance patterns of specific organisms. While oscillations in the persistence of the ice shelf breakout continue, under decadal patterns of climate variability the overall pattern is clear following catastrophic loss of ice shelf cover. The stratigraphic signature of this event can be compared to ancient glaciomarine sections in the Cryogenian Period, such as from the Pan-glacial Neoproterozoic “Snowball” intervals (the Sturtian and Marinoan at  ~720 and ~635 Ma) and the late Paleozoic Gondwanan succession in the earliest Permian (at 298 Ma). These comparisons are informative on how rapid changes in environment, while considered catastrophic in “our modern vernacular,” served to initiate rapid changes in biodiversity and evolutionary pace in the ancient Earth system.

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