The hypothesis that large ice sheets were present in both hemispheres ∼41.6 million years ago is tested, using marine sediment records from the equatorial Atlantic Ocean. The estimates of ice volume at this time can easily be accommodated on Antarctica, but were not the Northern Hemisphere. These findings support climate model simulations, which indicate that the threshold for continental glaciation was crossed earlier in the Southern Hemisphere than in the Northern Hemisphere, due to the different land–ocean distributions at the two poles.
- Kirsty M. Edgar
- Paul A. Wilson
- Yusuke Suganuma
