Scientists are increasingly linking Antarctic ice sheet to the level of carbon dioxide in the atmosphere. Supporting the idea, a new research published in the Journal Science claimed that during the time when ice sheet first started appearing, a fall in CO2 in atmosphere may have let ice sheet to form.

According to the research, the period known as the Eocene-Oligocene boundary, which prevailed some 34 million years ago, is believed to have been an era that led to periods of glaciations. The research has found that falling level of carbon dioxide back then has initiated ice sheet growth.

“Before 33.6 million years ago, there was no ice, and CO2 was above 750, was above the threshold”, said Simone Galeotti, lead author of the new study done by a large international collaboration of authors, and also a researcher at the Università degli Studi di Urbino in Italy.

Later came a transitional period where there was lower carbon dioxide concentration in the atmosphere and a variable ice sheet. About 32.8 million years ago, carbon dioxide levels dipped below 600 parts per million; at this time, Antarctic ice sheet expanded greatly.

The research was conducted by analyzing kilometer-long ocean sediment in the deep ocean. These were taken from the western part of the Ross Sea, somewhat near to United States’ McMurdo station.

The key bits of rock in different layers of the core indicated that by 32.8 million years ago, the icebergs broke into ice sheets due to emerging warmth and spread across Antarctica. Some icebergs floated on sea while some other melted, the rocks which are used as geological evidence were once carried by ice which fell to the sea floor.