cataclysm
Some events may have small consequences, while others are nearly cataclysmic in their impact.
The Depression was a worldwide cataclysmic event.
Greenhouse gases could cause a cataclysmic change in the world's climate.
Saturn’s rings weren't formed by a single cataclysmic event.
The consequences of bankruptcy are potentially cataclysmic.

SMART Vocabulary: related words and phrases

Causing things to happen
activation
actuation
agent
attribute
attribute something to someone
hyperstimulate
hyperstimulation
implement
implementation
in
launch pad
prompt
put someone to somethingidiom
Pygmalion effect
reactivate
realization
realize
render
spark
spell

You can also find related words, phrases, and synonyms in the topics:

Accidents and disasters