In the 19th century, Croll and Pilgrim stressed the importance of severe winters as a cause of Quaternary ice ages. Later on, mainly during the first half of the 20th century, Köppen, Spitaler and Milankovitch regarded high winter and low summer insolation as favoring glaciation. After Köppen and Wegener related the Milankovitch new radiation curve to Penck and Brückner's subdivision of the Quaternary, there was a long lasting debate whether or not such changes in the insolation can explain the Quaternary glacial-interglacial cycles. In the 1970s, with the improvements of radiometric dating, and of acquiring and interpreting the long continuous geological records, with the advent of computers and with the development of more sophisticated astronomical and climate models, the astronomical theory and in particular its Milankovitch version were revived. Over the last 5 years, most geological, astronomical and climatological obstacles have been overcome and the causal role of the orbital variations in long-term variation of climate is taken almost universally for granted. Models of different categories of complexity, from conceptual ones to 3-D atmospheric general circulation models and 2-D time-dependent models of the whole climate system have now been astronomically forced in order to test the physical reality of the astronomical theory. For example, experiments with both low- and high-resolution GCMs show that the increased seasonality at 9,000 BP, leads to intensified summer monsoon circulation of Africa and southern Asia. On the other hand, seasonal models for simulating the transient response of the climate system to astronomical forcing are also developed and the output of these most recent modeling efforts compares favorably with data of the past 400,000 years. Accordingly, the model predictions for the next 100,000 years are used as a basis for forecasting how climate would evolve when forced by orbital variations in the absence of anthropogenic disturbances: the long-term cooling trend which began some 6,000 years ago will continue for the next 5,000 years, this first temperature minimum will be followed by an amelioration around 15,000 AP (after present), by a cold interval centered at 23,000 AP, and by a major glaciation at around 60,000 AP.