Spade:
The sign that indicate we're living in the “last days” is composite. It's only been in the 20th century that there was two World Wars and a global terrorist threat. It's only been in the 20th century that we've had the technology to "ruin the earth."
You're begging the question. You had pestilence, famine, destructive earthquakes, etc all within a generation's lifetime, killing a greater percentage of the world's population than that of the generation that was born since 1914... Oh wait a minute. I forgot that the light got brighter! There no longer is a time frame with which to measure a "generation".
In any case, any major destruction in the future will come from Global Warming which is not predicted in the Bible any more than terrorism is. The technology that led to the release of Carbon Dioxide, which eventually led to Global Warming, began during the Industrial Revolution. That started in the late 18th century.
Also, the technology to "ruin the earth", from your point of view, I presume, is your reference to nuclear weapons. They were not invented in 1914.
Villabolo