/sci/ - Science & Math

Aside from a massive environmental disaster or acts of God (supervolcano, meteor, solar flare), how would worldwide civilization collapse in a relatively short period of say 5 years? Looking back at history and the fall of empires, usually things happen gradually due to societal decay, invasions etc, but we haven't had a massive worldwide collapse yet. Countries nowadays have food and energy reserves too.

Are viruses and global nuclear war the only plausible way our civilization ends? We've seen economic collapses happen on national scales like Venezuela, but could that happen on a global scale?