Description
Throughout as much as 80% of the 4 1/2 billion years of Earth’s history, the climate has been warmer than it is today. Certainly, the principal reason for this relates to the fact that during most of Earth’s history, carbon dioxide concentrations were markedly higher in the Earth’s early atmosphere.1 Primarily, this is the result of there being much less life, especially in Earth’s earliest history three to four billion years ago.
