In the technique example, it sounds like they used a homograph (or homoglyph) method to trick the AI -- almost as if the AI has 'eyes' and reads like a human would. This is so interesting.
Only thing I can think of at the moment, geologically-speaking and within a short time span could be a Super-volcano eruption that engulfs the atmosphere in smoke, causing another ice-age. Another method of danger could be a meteor impact, though it's time span is unknown until we detect it, and not sure if that fits your geological category.
The inactive CSS feature is great, I've spent a lot of time cleaning up global stylesheets for my employer recently, and it's a big task. Even though I doubt it catches CSS toggled by Javascript, I'm excited to use it.
If you can find an exchange that doesn't require Personal Identifiers (PID) before purchasing, you'd be in luck. Even localbitcoins.com sellers require enormous amount of info about the buyers before they even consider the transaction.