New calculations show that sensitivity of Earth's climate to changes in the greenhouse gas carbon dioxide (CO2) has been consistent for the last 420 million years, according to an article in Nature by geologists at Yale and Wesleyan Universities.
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This study used 500 data points in the geological records as "proxy data" and evaluated them in the context of the CO2 cycling models of co-author Robert Berner, professor emeritus of geology and geophysics at Yale who pioneered models of the balance of CO2 in the Earth and Earth's atmosphere.
"Proxy data are indirect measurements of CO2 - they are a measure of the effects of CO2," explained co-author Jeffrey Park, professor of geology and geophysics at Yale who created the computer simulations for the project. "While we cannot actually measure the CO2 that was in the atmosphere millions of years ago, we can measure the geologic record of its presence. For example, measurement of carbon isotopes in ancient ocean-plankton material reflects atmospheric CO2 concentrations."
Hmmm, wonder which 500 points in 450 million years they chose to use:
Global Surface Temperature and Atmospheric CO2 over Geologic Time
Late Carboniferous to Early Permian time (315 mya -- 270 mya) is the only time period in the last 600 million years when both atmospheric CO2 and temperatures were as low as they are today (Quaternary Period ).
Temperature after C.R. Scotese
CO2 after R.A. Berner, 1994
- There has historically been much more CO2 in our atmosphere than exists today. For example, during the Jurassic Period (200 mya), average CO2 concentrations were about 900 ppm or about 2.5 times higher than today. The highest concentrations of CO2 during all of the Paleozoic Era occurred during the Ordovician Period, exceeding 6000 ppm -- more than 16 times higher than today.
- The Carboniferous Period and the Ordovician Period were the only geological periods during the Paleozoic Era when global temperatures were as low as they are today.
To the consternation of global warming proponents, the Late Ordovician Period was also an Ice Age, with CO2 concentrations nearly 15 times higher than today-- 5500 ppm. According to greenhouse theory, Earth should have been exceedingly hot. Instead, global temperatures were no warmer than today. Clearly, other factors besides atmospheric carbon influence earth temperatures and global warming.
