Revelations that atmospheric carbon dioxide levels plunged by 40% before and during the formation of the Antarctic ice sheet 34 million years ago has confirmed the capacity of C02 to dramatically alter global climate.
Previous studies suggested that atmospheric C02 over the Southern Ocean was climbing during the Eocene to Oligocene climate transition, when ice first formed over Antarctica. This presented a conundrum, suggesting the climate was warming at the same time as Antarctica was freezing.
But when the ancient Southern Ocean currents and temperatures of that period were factored in, it became apparent that Antarctica’s big freeze followed a fall in C02 levels.
The study confirms that significant falls in the greenhouse gas result in global cooling, just as rises result in global warming.