The greenhouse gas that has become a bane of modern society, may have saved Earth from freezing over early in the planet’s history, according to the first detailed laboratory analysis of the world’s oldest sedimentary rocks. Scientists have theorized for years that high concentrations of greenhouse gases could have helped Earth avoid global freezing in its youth by allowing the atmosphere to retain more heat than it lost. Now a team from the University of Chicago and the University of Colorado at Boulder that analyzed ancient rocks from the eastern shore of Hudson Bay in northern Quebec, Canada, have discovered the first direct field evidence supporting this theory. The study shows carbon dioxide in Earth’s atmosphere could have sustained surface temperatures above freezing before 3,75 billion years ago.
Identification of chemical sedimentary protoliths using iron isotopes in the > 3750 Ma Nuvvuagittuq supracrustal belt, Canada

CU Boulder – Geological Sciences: Geobiology & Astrobiology