Stephen G Warren PI, Richard E Brandt, Regina C Carns
Department of Atmospheric Sciences Box 351640
University of Washington, Seattle, 98195-1640 USA
The climatic changes of the Neoproterozoic time, 600−800 million years ago, included episodes of
extreme glaciation, during which ice may have covered nearly the entire ocean for several
million years, according to the "snowball earth" hypothesis. The proposed work is to study
processes that would have been important on an ice−covered ocean during such an event. In
tropical regions of net sublimation, ice surfaces may have included (a) bare, cold sea ice
(perhaps cold enough that sodium chloride precipitated), (b) sea ice with a salt crust formed as
a lag deposit, and (c) cold glacier ice exposed by sublimation of "sea−glaciers"
(self−sustaining ice shelves) flowing from polar seas into the dry tropics. These ice types
would have been widespread on the tropical ocean of a Snowball Earth, but they now exist only in
Antarctica. Their albedos and surface properties will be investigated on naturally−occurring
modern analogues: (a) bare cold sea ice near the coast of Antarctica in early spring; (b) a
salt−encrusted lake in the McMurdo Dry Valleys; (c) "blue ice" areas of the Transantarctic
Mountains that have not experienced melting.