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Project Progress

1. Low-temperature life.
Warren and his student, Stephen Hudson, wrote a comment that casts doubt on a published claim of bacterial activity in South Polar snow, because of the lack of liquid water: Warren, S.G., and S.R. Hudson, 2003: Bacterial activity in South Pole snow is questionable. Applied and Environmental Microbiology, 69, 6430-6431.

2. Snowball Earth review.
Warren is drafting a paper "Ocean surfaces on Snowball Earth: implications for survival of surface life.". This paper identifies 13 different surface types that would occur at different times and latitudes during a snowball event, and recommends their albedos for use in climate modeling. Warren presented a poster on this topic at the conference on "Challenges in the Climate Sciences," Blois , France , 23 May 2004 .

3. Laboratory experiments relevant to Snowball Earth.
During a Neoproterozoic "Snowball Earth" event, the ocean surface conditions would determine both the surface climate and the locations for survival of surface life. A process that may be important in the tropical zones (where evaporation exceeds precipitation), as sea ice sublimates, is accumulation of a crust of sea-salt on the ice surface. This can only happen on ice below the eutectic temperature of NaCl brine, -22.9° C, but such temperatures are expected on Snowball Earth, even at the equator. No modern surrogate is known to exist in nature now, but we can investigate these processes in our cold-room laboratories. The salt that would accumulate is not NaCl but rather NaCl^.2H₂O, "hydrohalite," which has not received much investigation. Bonnie Light is collaborating with Warren on this project. She has begun preparations for laboratory studieson (a) migration rates of brine inclusions and salt crystals in ice at low temperatures, (b) the accumulation of salt on sublimating artificial sea ice, (c) suppression of sublimation by a salt crust, (d) cohesive properties of hydrohalite crystals (to determine whether wind will dislodge them), and (e) the absorption spectrum of hydrohalite.