We hope that these will never strike, but life has shown us time and time again that tragedy is inexorable. When one comes, which of these will it be?

In all cases, >10 million people displaced or 100,000 dead, within a year. Must also start counting after this question and either be "new" or 10-fold worse than usual; for example, annual fluctuations (even significant) in the flu must be 10x+ worse than normal range.

This question's close date is fluid; it may be extended indefinitely until criteria are met.

This list is exclusive and ignores other disasters that would qualify (e.g. earthquakes, meteors, war, and so forth), but is otherwise as broad and flexible within the listed categories as I can imagine:

• "Nuclear": intentional or accidental; explosion or meltdown; weapon, power plant, stockpile, or any other nuclear material source; can be multiple events of the same subtype, but effects must be within the timeframe.

• "AI": intentional, accidental, or collateral; caused by artificial or synthetic intelligence(s) in any form, may further instigate these or any other disasters (then resolves equally to AI + primary source of human cost, if listed).

• "Pandemic": infections of humans. viral, bacterial, technological, or other; natural, emergent, artificial, extraterrestrial, or other.

• "Climate": extreme, anomalous, or anthropic; change in global weather flows, storms, acute temperatures, sea changes, ecosystem crash, etc., so long as the cause and human costs are easily associable to each other.