Analyses of ice cores drilled through Greenland and Antarcitica ice sheets and high glaciers have produced remarkable advances in our understanding of the evolution of Earths climate. The past a few years have seen a revolution in our thinking on climate variability and tropic climate sensitivity, because of the signs of fast climate oscillations and cooling ice age tropics displeayed in the ice cores. One of the principal progress made by GRIP and GISP2 ice cores has been the demonstration that the last glacial period was punctuated by a series of abrupt warm interstadials during which temperature increased by about 5℃-8℃ for a few hundred years. Another sigificant new finding has been the document that the Eemian interglacial was interrupted by a series of severe cold periods, which began extremely rapidly and lasted from decades to centuries. Thirdly, a high glacier ice core opens a view of the ice age tropics. Two ice cores from Andes found that the tropics did share in the cooling as much as 8℃ to 12℃ lower than today during the late glacial stage. And the last, analysis of borehole temperature at GISP2 reveals that polar amplification of climate change is a central characteristic of Earths climate. With these new discoveries, the widely accepted concepts of a noisy glacial climate and a quiet interglacial climate as well as thermostat tropics came under challenge. And they result in the questions about the consequences of future global warming. Will the greenhouse effect end the recent climate stability and bring rapid climate change to our doorstep?