Giant Tabular Icebergs as Surrogate Ice Shelves in Field Studies of Antarctica's Response to Environmental Warming.

The past 3 years have witnessed approximately 6000 km³ of ice calved from the Antarctic ice sheet as a handful of extremely large tabular icebergs in the Ross and Weddell Seas. Several of these icebergs are comparable to many of the smaller, fringing ice shelves that surround the continent, and which have become the subject of concern since the recent sudden break-up of Larsen B ice shelf on the Antarctic Peninsula. While the drift and melting of these giant icebergs over the coming decades will undoubtedly have some impact on oceanic conditions beyond the Antarctic, the principal interest in these great wandering ice masses is motivated by the "natural experiments" their evolution in response to northward drift entails. In particular, the melting (both surficial and basal) and fragmentation of these icebergs in response to warmer conditions encountered in the Southern Ocean beyond Antarctica may closely resemble the effects future climate change may have on the stationary ice shelves along the coast of Antarctica. In recognition of this opportunity, we have been maintaining a suite of instruments, including GPS, automatic weather stations, ice-sounding sonars and seismometers on two icebergs in the Ross Sea (B15a and C16), and intend to place such a suite on the Drygalski Ice Tongue in anticipation of it's future calving (to be performed in October, 2003). Our poster summarizes the observations made so far, and discusses the potential for deploying new sensors and undertaking additional field campaigns to examine how these icebergs will ultimately disintegrate.