Why is the 20th century considered a century of crisis?

The 20th century is regarded as a century of crisis as a result of the unpleasant happenings all over the world during this period.

These happenings resulted in a mass loss of lives and properties as a result of most countries believing the best way to solve conflicts was through warfare . They include The World Wars , Russian Revolution, Economic depression , the different wars in Europe, Pacific and the holocaust.