Rocks Cooled the Whole Planet 15 Million Years Ago

New indications as to what initiated a long phase of cooling in Earth’s climate and kept it going may debunk a long-held theory about the pre-ice-age cooling.

Fifteen million years ago, the Earth’s climate entered into a period of slow, continuous cooling, and simultaneously the Antarctic ice sheet grew steadily larger. Finally, around 2.5 million years ago, ice covered Greenland, thrusting the Earth into its current bipolar ice age.

Geoscientists have been debating what brought about this global cooling for many years. Some argue that major mountain ranges such as the Andes, the Himalayas, and the Alps started to form 15 million years ago, and that they accelerated erosion and the weathering of rocks. This theory posits that the formation of mountains drew more carbon dioxide (CO2) from the atmosphere than processes such as volcanic eruptions were giving off, causing temperatures to continuously decrease.

Researchers have now demonstrated that this hypothesis is not accurate enough. Read more.