IEDA
Project Information
Ocean Surfaces on Snowball Earth
Start Date:
2012-09-01
End Date:
2015-08-31
Description/Abstract
The climatic changes of late Precambrian 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. These episodes would hold an important place in Earth?s evolutionary history; they could have encouraged biodiversity by trapping life forms in small isolated ice-free areas, or they could have caused massive extinctions that cleared the path for new life forms to fill empty niches. What caused the Earth to become iced over, and what later caused the ice to melt? Scientific investigation of these questions will result in greater understanding of the climatic changes that the Earth can experience, and will enable better predictions of future climate. This project involves Antarctic field observations as well as laboratory studies and computer modeling.

The aim of this project is not to prove or disprove the Snowball Earth hypothesis but rather to quantify processes that are important for simulating snowball events in climate models. The principal goal is to identify the types of ice that would have been present on the frozen ocean, and to determine how much sunlight they would reflect back to space. Reflection of sunlight by bright surfaces of snow and ice is what would maintain the cold climate at low latitudes. The melting of the ocean required buildup of greenhouse gases, but it was probably aided by deposition of desert dust and volcanic ash darkening the snow and ice. With so much ice on the Earth?s surface, even small differences in the amount of light that the ice absorbed or reflected could cause significant changes in climate. The properties of the ice would also determine where, and in what circumstances, photosynthetic life could have survived. Some kinds of ice that are rare on the modern Earth may have been pivotal in allowing the tropical ocean to freeze. The ocean surfaces would have included some ice types that now exist only in Antarctica: bare cold sea ice with precipitated salts, and "blue ice" areas of the Transantarctic Mountains that were exposed by sublimation and have not experienced melting. Field expeditions were mounted to examine these ice types, and the data analysis is underway. A third ice type, sea ice with a salt crust, is being studied in a freezer laboratory. Modeling will show how sunlight would interact with ice containing light-absorbing dust and volcanic ash. Aside from its reflection of sunlight, ice on the Snowball ocean would have been thick enough to flow under its own weight, invading all parts of the ocean. Yet evidence for the survival of photosynthetic life indicates that some regions of liquid water were maintained at the ocean surface. One possible refuge for photosynthetic organisms is a bay at the far end of a nearly enclosed tropical sea, formed by continental rifting and surrounded by desert, such as the modern Red Sea. A model of glacier flow is being developed to determine the dimensions of the channel, connecting the sea to the ocean, necessary to prevent invasion by the flowing ice yet maintain a water supply to replenish evaporation.
Personnel
Person Role
Warren, Stephen Investigator
Light, Bonnie Co-Investigator
Campbell, Adam Co-Investigator
Carns, Regina Co-Investigator
Dadic, Ruzica Co-Investigator
Mullen, Peter Co-Investigator
Brandt, Richard Co-Investigator
Waddington, Edwin D. Co-Investigator
Funding
Antarctic Integrated System Science Award # 1142963
Antarctic Integrated System Science Award # 0739779
AMD - DIF Record(s)
Data Management Plan
None in the Database
Product Level:
Not provided
Datasets
Repository Title (link) Format(s) Status
PI website Ice on the Oceans of Snowball Earth Project Data None exist
Publications
  1. Hoffman, P. F., Abbot, D. S., Ashkenazy, Y., Benn, D. I., Brocks, J. J., Cohen, P. A., … Warren, S. G. (2017). Snowball Earth climate dynamics and Cryogenian geology-geobiology. Science Advances, 3(11), e1600983. (doi:10.1126/sciadv.1600983)
  2. Light, B., Carns, R. C., & Warren, S. G. (2015). “Albedo dome”: a method for measuring spectral flux-reflectance in a laboratory for media with long optical paths. Applied Optics, 54(17), 5260. (doi:10.1364/ao.54.005260)
  3. Carns, R. C., Light, B., & Warren, S. G. (2016). The spectral albedo of sea ice and salt crusts on the tropical ocean of Snowball Earth: II. Optical modeling. Journal of Geophysical Research: Oceans, 121(7), 5217–5230. (doi:10.1002/2016jc011804)
  4. Light, B., Carns, R. C., & Warren, S. G. (2016). The spectral albedo of sea ice and salt crusts on the tropical ocean of Snowball Earth: 1. Laboratory measurements. Journal of Geophysical Research: Oceans, 121(7), 4966–4979. (doi:10.1002/2016jc011803)
Platforms and Instruments

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