http://www.scotese.com/climate.htm

The vostok ice core data only covers the last 500 thousand years, but what about the last 500 million years?  This site has a little graph that shows Earth was 10 degrees C warmer than it is now during most of the Triassic, Jurassic, and Cretaceous periods.  It's based on a model of plate tectonics and assumptions about the conditions under which certain kinds of rocks form.   It assumes Laterite,  Bauxite, Glendonite, and Kaolinite form in warm conditions while Tillite, Dropstone, and Glendonite form in cool conditions.  So it can sort of map out the latitudes at which tropical regions existed in different time periods and extrapolate the global mean temperature from that.   According to this website there have been several periods of millions of years when there was no polar ice at all, based on analysis of sedimentary rocks.

Can any of you debunk that stuff?  If it's true then global warming doesn't seem that bad.  New Orleans and Miami are still screwed eventually, but "runaway global warming" is far off.   If it's true there appears to be a very strong negative feedback that prevents the global mean temperatrue rising above 22C.   I've been trying to think of what it could be, and came up with three possibilites:

 1. Higher temperatures make rocks erode and dissolve faster.  Greenhouse gasses could be sequestered by being combined with components of those rocks.

2. Change in meteorological patterns increases the albedo of tropical regions.

3. Ozone decreases due to stratospheric cooling, allowing more transmittance around the peak of the 310K black body radiation curve.

The wikipedia article on the author doesn't have much:  http://en.wikipedia.org/wiki/Christopher_Scotese

Also, I found a graph of carbon dioxide over millions of years:

http://www.globalwarmingart.com/images/7/76/Phanerozoic_Carbon_Dioxide.png

 According to that, CO2 levels were around 2000ppm during that period, over 5 times their present level of 385ppm.    Do any of you find evidence to the contrary?