10.18113/D3NK52
David Pollard. Earth and Environmental Systems Institute, Pennsylvania State University, University Park, Pennsylvania, USA. James F. Kasting. Department of Geosciences, Pennsylvania State University, University Park, Pennsylvania, USA. Michael E. Zugger. Applied Research Laboratory, Pennsylvania State University, State College, Pennsylvania, USA.
Coupled GCM and sea-glacier modeling for Snowball Earth
Penn State Data Commons
2017
Dataset
During Snowball Earth episodes of the Neoproterozoic and Paleoproterozoic,
limited amounts of tropical open ocean (Jormungand), or tropical ocean with
thin ice cover, would help to explain (1) vigorous glacial activity in low
latitudes, (2) survival of photosynthetic life, and (3) deglacial recovery
without excessive buildup of atmospheric CO2. Some previous models have
suggested that tropical open ocean or thin-ice cover is possible; however
its viability in the presence of kilometer-thick sea glaciers flowing from
higher latitudes has not been demonstrated conclusively. Here we describe a
new method of asynchronously coupling a zonal sea-glacier model with a 3-D
Global Climate Model, and apply it to Snowball Earth. Equilibrium curves of
ice line vs. CO2 are mapped out, as well as their dependence on ocean heat
transport efficiency, sea-glacier flow, and other model parameters. No climate
states with limited tropical open ocean or thin ice are found in any of our
model runs, including those with sea glaciers. If this result is correct, then
other refugia such as cryoconite pans would have been required for life to
survive. However, the reasons for the differences between our results and
others should first be resolved. It is suggested that small-scale convective
dynamics, affecting fractional snow cover in low latitudes, may be a critical
factor accounting for these differences.