You may want to read the paper that I send yesterday. Unraveling the ice ages needs a lot of interpretation of evidence, the affirming the consequent fallacy. For instance the dating of southern hemisphere warming is thought to be indicated with a stable isotope jump (dD, d18O) in the ice cores of the Antarctic (Vostok, Dome C etc). For instance, dating of low accumulation cores is very hard without annual stratification visual, so one is depending on estimating accumulation rate and compression rate between hard dating points. So the assumption is made that both temperature and precipitation (accumulation) and isotopes corrolate 100%, based on this the annual layering is reconstructed, and based on this ,the dating is reconstructed. It seems that there is no hard dating point between some 11000 years ago and 28000 years but the assumed warming point 17000 years is somewhere in the middle and hence highly subceptible to errors. In this PhD thesis, here you can see the potential error with that assumption: http://www.phys.uu.nl/~helsen/PDF/thesis.pdf The big problem is that the sudden (clathrate induced) isotope / precipitation spike goes way outside of the parameter range and hence gives a false dating conclusion. The Greenland ice cores have a much higher accumulation rate and consequently are much better datable. But the result is that the dating of warming get's more and more enigmatic (28 - 19 - 17 - 14.6 thousend years ) Take your pick. These problems are all caused by not considering the clathrate events in the equation. For a complete overview of all this research perhaps check the mega work of Spence Weart: http://www.aip.org/history/climate/ However, without Clathrate, all conclusions are worthless/ We have to get back to the basics.