Jesus said that when he comes the situation would be as it was in the days of Noah [Luke 17:26].
Genesis 6 tells us that in Noah's day, the earth was corrupt and filled with violence. Human society in that era was relatively small and relegated to a single area of the earth so that the corruption and violence affected everyone.
After the flood and the dispersion of humanity around the world it has only been in our day that the world is once more like a village where news travels almost instanteously from one end to the other. The earth is now utterly corrupt on a political, military, moral, ecological level to the point that "mens' hearts are failing them for fear" [Luke 21:26] and it is filled with the most appalling violence on a scale that would make the violence in Noah's day pale to insignifcance. There would be other signs such as earthquakes which would be on an unprecedented scale.
So, combine the moral corruption in the world with signs in the very geography of the planet never mind the amazing fulfillments of Bible prophecy in the Middle East, and we have an assurance that the Lord' return is near at hand.
Here is a link to information about your question:
I hope you have found this helpful.