What kind of Ice Age would cause an apocalypse?

It's 2070, global warming is a terrifying reality. Coastal cities such as New York and Shanghai has already fallen to rising sea levels and extreme weather. In an effort to stem and perhaps counteract this global phenomenon, the brightest minds of Earth have developed a substance called Cryion. The Cryion was released into the air, but it worked too well. The pendulum swung the other way, causing the Earth to rapidly cool.

How Severe must the coming Ice Age be to cause an Apocalyptic Scenario?

Such a Scenario is defined by:

• All or almost all above ground human settlements are destroyed or rendered uninhabitable.
• Most of humanity is wiped out, with less than 100,000 surviving across the globe in perhaps small, mostly underground, communities.
• The ice age hasn't made the world completely barren or uninhabitable, and mass extinction didn't mean total extinction
• What communities that survive can still build a semi-sustainable living
• Most technologies are rendered useless, or at least their construction and maintenance mostly lost to time

I'm looking mostly for kinds of weather conditions, how cold it'd have to be, how quickly the Ice Age happens, and any other things that come to mind.

posted over 7 years ago

Jim Wu‭

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