Researchers at Purdue and Yale universities said the role of the greenhouse gas in the Antarctic shows carbon dioxide's importance in past climate change and points to CO2 as a significant force in present and future climate.
The team identified a threshold for low levels of carbon dioxide below which an ice sheet forms in the South Pole, but how much the greenhouse gas must increase before the ice sheet melts is still a mystery, they said in a release Thursday.
"The evidence falls in line with what we would expect if carbon dioxide is the main dial that governs global climate; if we crank it up or down there are dramatic changes," Matthew Huber, a Purdue professor of earth and atmospheric sciences, said. "We went from a warm world without ice to a cooler world with an ice sheet overnight, in geologic terms, because of fluctuations in carbon dioxide levels."
During a span of 100,000 years at the end of the Eocene epoch, temperatures fell dramatically, many species of animals became extinct, ice covered Antarctica and sea levels fell, researchers said.
"The onset of Antarctic ice is the mother of all climate 'tipping points,'" Yale geochemist Mark Pagani said. "Recognizing the primary role carbon dioxide change played in altering global climate is a fundamentally important observation."