A First: Ice Caps Linked to Carbon Dioxide

It seems an unlikely place to have to go in order to uncover one of the key mysteries of the Antarctic ice cap's history, but Tanzania is the source of some remarkable rock samples, on which the performance of geochemical analysis has significantly advanced our understanding of global climate science.

A team of British and American scientists has determined that the formation of the ice cap approximately 34 million years ago followed a long period of decline in atmospheric carbon dioxide, with expansive growth in ice cover after atmospheric chemistry dipped and stayed below a critical threshold.

As reported by PhysOrg.com, the team located marine sedimentary rock samples in Tanzania that spanned the time prior to, during and following the formation of the ice caps. The chemistry of the micro-fossils extracted from those samples revealed the changes in atmospheric chemistry over time, and allowed the research team to associate the ice cap formation with the surpassing of an atmospheric tipping point when carbon dioxide levels went below 760 parts per million following a period of steady decline over many millions of years.

There's no denying the importance of the study (which appears in the journal Nature), and co-author Bridget Wade of Texas A&M University ponders the significance as reported by PhysOrg.com:

"This was the biggest climate switch since the extinction of the dinosaurs 65 million years ago. Our study is the first to provide a direct link between the establishment of an ice sheet on Antarctica and atmospheric carbon dioxide levels and therefore confirms the relationship between carbon dioxide levels in the atmosphere and global climate."

Photo courtesy of Koyos, via Wikimedia Commons