Why did antarctica’s climate change approximately 50 million years ago?

Antartica was a forested continent about one million years ago. This continent was full of life. There was a sudden decrease in the level of carbon dioxide and in the atmosphere at that time. This increase in the amount of carbon dioxide in the atmosphere resulted in dropping the temperature of Antartica. This temperature change drifted the continent towards south. The continent kept on cooling and resulted in developing ice and snow.