The key to the analysis of ancient climates is the geologic time scale that was developed from the 17th to 20th centuries. Scientific can use ancient rocks to determine processes that were occurring in the billions of years of the Archaean and Proterozoic Eons. There are two major climate controversies from the Archaean and Proterozoic eons: the faint young sun paradox and the cause of equatorial glaciations. One proposed solution is that the entire earth was covered by a thick sheet of ice. The other is that earth's axis was tilted toward the sun.
The Archaean Eon began after the Late Heavy Bombardment and ended shortly before the Great Oxidation Event. It had an orange haze atmosphere and invisible sun (Figure 7-3). Algae photosynthesis caused huge surges in dissolved oxygen concentration in the ocean. Asteroid impacts ended with the Late Heavy Bombardment so the atmosphere was primarily carbon dioxide and other gases from volcanic emissions. Because of absorption of oxygen by rock formations, the atmosphere remained anoxic even with generation of oxygen by algae prior to the Great Oxygenation Event.
From a geological perspective, the Proterozoic Eon was the best of times and the worst of times. Two of the most contentious and thus exciting geologic periods bracket the ends of the Proterozoic; however, the middle Proterozoic is the "boring billion." This section will focus on the evidence for equatorial glaciation at the beginning (Paleoproterozoic) and end (Neoproterozoic) of the Proterozoic and the proposed causes of the equatorial glaciations. Scientists debate whether the cause of equatorial glaciations was a snowball Earth or a different tilt of Earth's axis.
The climate has been remarkably stable during the 541 million years of the Phanerozoic Eon. The average global temperature has generally remained within a 10 degree centigrade hospitable range for life on Earth. Within this range, several factors influence climate, one of which is greenhouse gases and another is solar and orbital dynamics.
In the fourth age, Moses first described the natural appearance of the sun and moon in the sky. Moses then described a miracle in which God moved the sun and moon (and stars) to different positions in the heavens, where they governed the day-night cycle.