In the thread about mammoths and climate scepticism, we have seen that the fossil remains of the Arctic Siberian mammoth steppe suggest that is was actually warmer than today, at least during summers. This mammth steppe existed throughout most of the final stages of ice age, the late Wisconian or Weichselian of the Pleistocene epoch, and raises question marks about the severeness of the cold of the ice age as inferred from the Greenland ice cores. Also an abundance of evidence was presented that the period between 17.5 and 14.5 thousand years ago, the Oldest Dryas or 'mystery interval', was also much warmer than expected. This is completely at odds with the paleo-temperature interpretations of the isotope ratios of the Greenland ice cores. In this thread I'd like to discuss, (not by monologue if possible) why and how this could have happened by analysing the hydrographic processes that change the isotope signatures. Things could get a bit technical, therefore I'd like to present some literature and textbooks first as reference and fundamentals of this little superficial analyses. For isotope fractination processes I refer to these links/textboox mentioned in the sublinks. http://wwwrcamnl.wr.usgs.gov/isoig/isopubs/ Furthermore for the analysis of the paleothermometer principles I like to use: http://www.ipsl.jussieu.fr/GLACIO/hoffmann/Texts/jouzelJGR1997.pdf [Broken], one of the first publications that attempted to proof the robustness of the isotope paleo-thermometer. more later.