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What Can Earth Paleoclimates Reveal About the Resiliency of Habitable States? An Example from the Neoproterozoic Snowball Earth. Linda E. Sohl , 1,2 Mark A. Chandler , 1,2 Jeffrey Jonas , 1,2 Alexander Pavlov , 3 Thomas Clune , 3 Anthony DelGenio , 2 Shawn Domagal-Goldman , 3 Michael Way 2. - PowerPoint PPT Presentation
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Habitable Worlds Across Time and Space STSci Symposium 2014
What Can Earth Paleoclimates Reveal About the Resiliency of Habitable States?
An Example from the Neoproterozoic Snowball Earth
Linda E. Sohl,1,2 Mark A. Chandler,1,2 Jeffrey Jonas,1,2 Alexander Pavlov,3 Thomas Clune,3 Anthony DelGenio,2 Shawn Domagal-Goldman,3 Michael Way2
1 Center for Climate Systems Research, Columbia University, New York, NY2 NASA Goddard Institute for Space Studies, New York, NY
3 NASA Goddard Space Flight Center, Greenbelt, MD
Habitable Worlds Across Time and Space STSci Symposium 2014
The Neoproterozoic “Snowball Earth”
Habitable Worlds Across Time and Space STSci Symposium 2014
How Do We Know It Was Cold?
All cold climate features found in rocks interpreted to have been deposited in
low-latitude regions
Habitable Worlds Across Time and Space STSci Symposium 2014
The “Hard Snowball Earth”
Habitable Worlds Across Time and Space STSci Symposium 2014
Conflicting Model Results
• 1D and 2D modeling produces “snapover effect” on sea ice cover once sea ice front reaches 30 degrees latitude– Tipping point is reached once sea ice front extends
under descending Hadley cell – sea ice albedo effect is self-sustaining
• 3D models with fully coupled oceans cannot achieve this frozen state unless key feedbacks are disabled (Poulsen and Jacobs, 2004)– “Slushball Earth” alternative hypothesis
Habitable Worlds Across Time and Space STSci Symposium 2014
3D Modeling of a Snowball Earth
• NASA/GISS ModelE2-R (Schmidt et al., 2014):– Atmospheric model with 2 x 2.5˚horizontal
resolution, 40 layers with top at 0.1 mb– Ocean model with 1 x 1.25˚ horizontal
resolution, 32 layers, Gent-McWilliams correction included (IPCC AR5 p5)
• Boundary conditions: – Paleogeography, no vegetation, solar
luminosity = 93.8% modern, CO2 = 40 ppm
Habitable Worlds Across Time and Space STSci Symposium 2014
Snowball Earth Global Mean Temperature: -
11.1 ˚C
Control Run Global Mean Temperature:
17.9 ˚C
Habitable Worlds Across Time and Space STSci Symposium 2014
Hypotheses
Habitable Worlds Across Time and Space STSci Symposium 2014
Snowball Earth Global Mean Temperature: -
11.1 ˚C
(Pierrehumbert, 2002)
Habitable Worlds Across Time and Space STSci Symposium 2014