Post-Apocalyptic Catastrophe

In a parallel universe, a parallel Earth, the earth there is due to tectonic movements that cause the land to rise and fall, the land masses to shift, and the visual pole to move, which changes the distribution and circulation patterns of the sea and land, causing the earth's temperature to drop. For some reason, the earth's temperature further becomes colder, thus ushering in the earth's great ice age. The surface of the earth is no longer suitable for human habitation, and humans are forced to live underground. However, humans discover an unknown civilization underground. How will the two civilizations collide... This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.