How do they speculate the next ice age?

Algorithms and statistical analysis softwares like SPSS etc. help the speculators in their predictions based on the data generated by the geologists about the last few ice ages.

Some Cold Facts

The Ice Age History

Ice age, as all must be knowing, is not just a fantasy limited to movies, sci-fi, Nat Geo or Discovery and science books. There is much teeth to the ice age story as told by Wikipedia on its page for Ice age. The history of ice age is so "cold" that merely the thought of one is enough to send chills down the spine of any person sufficiently knowledgeable about it. Ice ages, as told by the sedimentation under the uppermost layer of earth crust (the soil) and in the Arctic & Antarctica ice core-layers, was the detrimental period always occurring naturally without any human-intervention.

This graph sourced from Wikipedia depicts clearly that our planet is entering another Ice Age in just few years. This period is just a part of the interglacial period between two ice ages. We should stop worrying about greenhouse emissions. The planet Earth is much much stronger than us.