Researchers at the University of Sydney propose a new theory for Earth's longest ice age, known as Snowball Earth. They suggest that a global decrease in carbon dioxide emissions, caused by reduced volcanic activity, led to a drop in temperatures. This theory, published in the journal Geology, sheds light on how geological processes have impacted Earth's climate and may provide insights into current climate trends. The study's lead researcher, Adriana Dutkiewicz, emphasizes the role of geological processes in shaping Earth's climate, prior to human influence on carbon dioxide levels. This theory adds to the existing ideas about what caused the planet to enter an ice age.