Antarctic Glaciation Linked to Ancient CO2 Levels

These illustrations provide a model for the glaciation that occurred rapidly over 80,000 years during at the Eocene/Oligocene boundary. Color depicts sea ice and white represents land ice. Courtesy of Robert DeConto.

Scientists have long proposed a link between climate change and CO2 atmospheric levels. A recent paper published in Science by Yale Geology and Geophysics Professor Mark Pagani strengthens the argument that CO2 levels and temperature are closely related. Pagani and his collaborators demonstrated that the rapid glaciation of Antarctica near the Eocene/Oligocene boundary, which occurred approximately 34 millions year ago, correlated with atmospheric CO2 levels falling by approximately 40%. More importantly, their findings corroborated a model of glaciation proposed by fellow paleoclimatologist Robert DeConto; that model emphasizes the rapid decline of CO2 as the primary factor for the continental glaciation.

The massive freezing 34 million years ago was one of the most severe climate reorganizations in Earth’s history. In a span of 80,000 years, Antarctica transformed from a warm, ice-free continent to a frozen, glaciated land resembling what it is today. In order to determine ancient CO2 levels, Pagani and his team analyzed the isotope composition of carbon from deep-sea cores sampled from around the world. “Deep sea temperature can be calculated from a chemical signature that is embedded in alkenones, a class of organic molecules produced by photosynthetic organisms at the surface of the sea,” explained Pagani. Ultimately, he believes that this study provides even more reason to be concerned that current CO2 levels are the highest that they have been in over 5 million years.

Locations from where deep-sea cores were harvested. Courtesy of Professor Pagani.