Restart the Frozen Second Hand of the Earth

A hundred years ago, the "Great Cooling" caused glaciers to spread. The global average temperature was -30°C, 90% of the land was covered by ice and snow, and only a small amount of "low-cold livable zones" remained (controlled by technological oligarchs). The war in the old world led to nuclear leaks, and "red mist radiation belts" were scattered throughout the ruined areas. Long-term exposure can cause genetic aberrations or death.