Climate Change Over the Last 4.5 Billions Years

Here is a pretty amazing piece on the website 'The Resilient Earth'.  The author, Doug Hoffman, a computer scientist with a Ph.D. from UNC Chapel Hill, puts climate change in a vast historical and geological perspective, with great pictures and graphs.

These are his conclusions:

•Earth’s temperature is always changing.
•Over time there have been periods when it has been colder than it is today.
•For most of the Phanerozoic [last 542 million years] it has been much warmer than it is today.
•Life has persisted during periods both hot and cold.
•There is no one “right” temperature.
•Carbon dioxide has always been present in Earth’s atmosphere.
•Over time there have been periods when CO2 has increased and decreased naturally.
•For most of the Phanerozoic it has been much higher than it is today.
•Life has persisted during periods with high CO2 and low CO2.
•CO2 levels will change with or without human contributions.
•Over time there have been a number of ice ages—Life has endured multiple ice ages.
•For most of the Phanerozoic there have been no persistent polar ice caps.