Catastrophic ice shelf breakup as the source of Heinrich event icebergs

Abstract

[1] Heinrich layers of the glacial North Atlantic record abrupt widespread iceberg rafting of detrital carbonate and other lithic material at the extreme-cold culminations of Bond climate cycles. Both internal (glaciologic) and external (climate) forcings have been proposed. Here we suggest an explanation for the iceberg release that encompasses external climate forcing on the basis of a new glaciological process recently witnessed along the Antarctic Peninsula: rapid disintegrations of fringing ice shelves induced by climate-controlled meltwater infilling of surface crevasses. We postulate that peripheral ice shelves, formed along the eastern Canadian seaboard during extreme cold conditions, would be vulnerable to sudden climate-driven disintegration during any climate amelioration. Ice shelf disintegration then would be the source of Heinrich event icebergs.

On the reconstruction of palaeo-ice sheets: Recent advances and future challenges

“…Despite recent advances, there is no clear consensus about the timing and amount of meltwater and sediment flux during Heinrich events (Alley and MacAyeal, 1994;Johnson and Lauritzen, 1995;Hemming, 2004;Hulbe et al, 2004;Marshall and Koutnik, 2006;Marcott et al, 2011). Insufficient data have been collected near the different glacial outlets (Section 2.6), so that use of marine records has overemphasised Heinrich events and the postHeinrich event 1 deglaciation.…”

Simulating Heinrich event 1 with interactive icebergs

“…Given the fact that non-cooling icebergs do not have such a strong impact on the thickness of the sea-ice, and the fact that a closed sea-ice cover minimises the (sea-surface) erosion aspect of iceberg deterioration, this is probably due to the cooling of deeper, sub-surface, layers by the CF icebergs. In this context we would like to point out that Hulbe et al (2004) have postulated, on the basis of climate controlled meltwater infilling of surface crevices, that ''peripheral ice shelves, formed along the eastern Canadian seaboard during extreme cold conditions, would be vulnerable to sudden climate-driven disintegration during any climate amelioration. Ice shelf disintegration then would be the source of Heinrich event icebergs.''…”

“…5 HIC) illustrates that the climatological feedbacks could also play an important role in the growth of ice-shelves. In turn, catastrophically disintegrating ice-shelves can become a source of iceberg armadas (Hulbe et al 2004;Moros et al 2002;Polyak et al 2001).…”

The structural glaciology of southwest Antarctic Peninsula Ice Shelves (ca. 2010)

“…Swithinbank et al, 1988) and streaklines (e.g. Hulbe et al, 2004) are extended features aligned parallel to the principal ice-flow direction and are observed as dark and light couplets caused by shaded surface relief (Figure 2(C)). They are ubiquitous around Antarctica (Glasser & Gudmundsson, 2012) and typically exist in regions of 'active' ice, with their cumulative length governed by the timescale of decay relative to the time taken for ice to travel a certain distance, yet their genesis is unclear.…”