Douglas R. MacAyeal Professor, Department of the Geophysical Sciences and the College Department of the Geophysical Sciences 5734 S. Ellis Ave. HGS 413 Chicago, IL 60637 USA Phone: 773/702-8027 E-mail: drm7@uchicago.edu Publications Professor MacAyeal's Website

My work at the University differs from that of other climate-dynamics colleagues in the department by being oriented toward "field-data collection and processing." My approach to climate related science uses this field data as the means to establish proper, rational models of the physical processes governing climate. My field efforts in Antarctica (I've worked on the Ross Ice Shelf and in the Ross Sea for 10 field seasons) yield a range of physical models concerning the dynamics of large ice masses. For example, my work of about 10 years ago focussed on the processes of ice-stream flow, and the nature of the subglacial boundary layer that facilitates ice-stream basal lubrication. My models of ice streams were subsequently built upon by students at the U. of C. and colleagues elsewhere to determine the role of ice-stream surging in abrupt climate change of the North Atlantic (e.g., Heinrich events, when great armadas of icebergs plied the North Atlantic dropping ice-rafted debris and shutting down North Atlantic Deep Water production).

My current research passion involves the break-up of ice shelves and the subsequent transport of icebergs into the surrounding ocean. In 2002, the Larsen B Ice Shelf broke up by a melting-triggered ice-shelf fragmentation process (a figure from one of my recent papers, co-authored with a former student, Prof. Christina Hulbe, now at Portland State University, is provided below). My students and I plan to perform field work on the remaining Larsen B and Larsen C ice shelves to verify the hypothesis suggesting how ice shelves are linked to climate.

Projects:

• Giant Icebergs of the Ross Sea: Field work continues through winter, 2006. The picture shown above is of me standing next to one of the iceberg-tracking stations placed on iceberg B15A.
• Sensors and Sensor Networks: I am working to develop a wireless sensor network to monitor the seismicity and basal melting rates of icebergs as they drift through the Southern Ocean. This work, if funded, will be performed with colleages at Stanford University, Northwestern University, Kansas Universeity and the University of Wisconsin.
• Inverse methods in Glaciology: I occasionally advise colleagues interested in performing "adjoint trajectory" models of the Antarctic Ice Sheet for the estimation of otherwise unobservable parameters. The colleagues who do this work are located at NASA's JPL, GSFC and also University of Washington. To learn more about my research, consult my website.

Teaching:

• Ice-Age Earth: Much of what I teach is intended as general education for undergraduates at the U. of C., i.e., it is part of the "core curriculum." This popular class covers the subject of Pleistocene climate change, the methods involved in its discovery and its causes. I interact with approximately 6 graduate students from the department in the process of teaching this 1-quarter class, as all labs are run by graduate student assistants.
• Dynamic Environment: This class is an extension of the Ice-Age Earth class and is focussed on the emergence of recent, post-glacial climate and the impact of climate on human history. We study the evolutionary biology of hominid evolution, the peopleing of the globe during periods of reduced sea level, and finally, the onset of agriculture in the wake of the Younger Dryas Event.
• Settlement Systems: This is part 2 of the class above, and focusses on the development of irrigated agriculture in the post-glacial world. Much of what is taught in this class engages the student in geo-archaeology. To facilitate the teaching of this class, I interact with several students and colleagues at the Oriental Institute of the U. of C., one of the world's most impressive institutes devoted to the archaeology of the Near East.

Education:

• Ph.D., Princeton University, 1983

To find out more about me, my research and my teaching. Please log on to my website (listed above).

Caption: A figure from a recent publication (MacAyeal, et al., 2003) depicting (panels 1, 2 and 3 on left) satellite imagery of the collapse of Larsen B in Feb-March 2002. The 3,600 square kilometer ice shelf literally exploded into uncountable small fragments. Panel 1 depicts the ice shelf prior to the summer melt season (November, 2001). Panel 2 depicts the ice shelf in February, 2002, prior to break-up. Small meltwater ponds are visible as mottled streaks running toward the open Weddell Sea (black area on right of the ice shelf's calving front). Panel 3 depicts the ice shelf in late March, 2002, after break-up. Streaklines represent englacial debris that was not visible prior to break-up, indicating that many of the ice-shelf fragments have tipped over, or capsized. Panels a-d on the right show a sequence of schematic diagrams indicating how ice-shelf fragment capsize would enhance the explosive nature of the break-up. As fragments capsize, their capsize moment introduces an expansion stress in the remaining, unfragmented ice shelf (analagous to how expanding CO2 gas in champagne bubbles cause the fluid in a champagne bottle to expand and froth from the top of the bottle). This capsize/ice-shelf expansion feedback constitutes the driving mechanism of the process. Ice-shelf melting, in response to increased surface temperatures around the Antarctic, is the ultimate trigger, however, for ice-shelf break-up of this nature. This is because surface meltwater, through its propensity to wedge open various surface crevasses, is required as an agent needed to create the first ice-shelf fragments that begin to capsize. To see more about this topic, refer to my website.